bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of proteins and pH on fretting corrosion and metal ion release
Authors: Merritt Katharine , Brown Stanley A. 
Published: December 2004

AbstractThe objectives of this study were to determine the effect of proteins and protein charge on the corrosion of stainless steel. As Zwitter ions, proteins have a positive charge in solutions acidic to their isoelectric point (pI) and a negative charge in solutions basic to the pI. Fretting corrosion rates of stainless‐steel plates and screws as determined by weight loss and metal ion release were studied in saline and protein solutions with the pH adjusted to 3, 5, and 8. Alterations in pH did not affect the corrosion rate in saline solutions. However, alterations of the pH in albumin solutions did affect the corrosion rate. In protein solutions acidic to the isoelectric point the presence of the positively charged albumin did not alter the corrosion rates as compared to that in saline. However, the presence of negatively charged proteins in solutions basic to their isoelectric points decreased the amount of corrosion. Thus, the effect of proteins on fretting corrosion is dependent on the charge on the protein. When the release of nickel was compared to the release of chromium, it was shown that the release was in proportion to the composition of the alloy when fretting corrosion took place in saline. The nickel/chromium ratio in the albumin and gamma globulin solutions was increased relative to that predicted indicating preferential release of nickel in protein solutions.
An in vitro evaluation of the hemostatic activity of topical agents
Authors: Eloy Rosy , Baguet Joel , Christé Georges , Rissoan Marie Clotilde , Paul Jacqueline , Belleville Jean 
Published: December 2004

AbstractAn in vitro method has been developed for human non‐anticoagulated blood to evaluate the enhancing effect of hemostatic agents on both plasmatic and cellular activation of the coagulation cascade. The coagulation time and the sequential generation of fibrinopeptide A (FpA) have been used as parameters. The kinetics of generation of FpA has been modelized and mathematically analyzed using the latence time, the slope of the linear part of the curve, and the time necessary to reach half maximal amplitude of FpA in the tube. A very precise evaluation of the hemostatic activity of five different molecules, four being collagenous in nature, is given.
In vitro simulation of biocompatibility of Ti‐Al‐V
Authors: Bruneel Noël , Helsen Jef A. 
Published: December 2004

AbstractThe presented data are the result of a reappraisal of the biocompatibility properties of titanium alloys. An in vitro study has been conducted using Hanks' solution with four different additional compounds (EDTA, l‐leucine, Na‐citrate, and 8‐hydroxyquinoline). A measurable dissolution rate was observed for Ti and Al in a solution contaning EDTA and for Ti, Al, and V for a solution containing Na‐citrate. The dissolution kinetics are discussed and explained in terms of the composition of the surface layers. The results contain useful introductory information for an extended study of media allowing representative in vitro simulation of the in vivo behavior of titanium alloys.
Kinetics of cell adhesion to polymer surfaces
Authors: Absolom D. R. , Thomson C. , Hawthorn L. A. , Zingg W. , Neumann A. W. 
Published: December 2004

AbstractResults of the kinetics of adhesion of granulocytes as well as fresh and glutaraldehyde‐fixed erythrocytes, suspended in Hanks Balanced Salt Solution (HBSS; pH 7.2, ionic strength of 0.15) to various polymeric substrates are presented. Cell adhesion increases rapidly initially and reaches a plateau value after approximately 30 minutes. There is no evidence for a lag‐time in the onset of cell adhesion, suggesting that electrostatic double‐layer forces are negligible under these experimental conditions. For the experiments in which the cells are suspended in HBSS, which has a surface tension larger than that of the cells, the level of cell adhesion increases with decreasing surface tension of the polymeric substrates. An additional experiment with fresh human granulocytes suspended in HBSS containing 10% dimethyl sulfoxide was also performed. The surface tension of the resulting liquid medium is below that of the cells and the pattern of adhesion is reversed, in agreement with the predictions of a thermodynamic model for cell adhesion. The slightly different behavior of siliconized glass as a substrate is discussed in terms of „screening”︁.
Poly(dimethylsiloxane)‐poly(ethyleneoxide)‐heparin block copolymers. I. Synthesis and characterization
Authors: Grainger D. W. , Kim S. W. , Feijen J. 
Published: December 2004

AbstractAmphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS‐PEO‐Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable products with reactive end‐groups, while the final products demonstrate bioactive, covalently bound heparin moieties. Due to the solvent systems required, commercial sodium heparin was converted to its benzyltrimethyl ammonium salt to enhance its solubility. The same procedure was applied to heparin degraded by nitrous acid in order to covalently couple it in solutions with the semitelechelic copolymers. As might be expected, this derivatization reduces the apparent bioactivity of the heparin. However, preliminary findings suggest that the bioactivity can be restored by reforming the heparin sodium salt.
Development of Ni‐4 wt.% Si thermoseeds for hyperthermia cancer treatment
Authors: Chen J.‐S. , Poirier D. R. , Damento M. A. , Demer L. J. , Biancaniello F. , Cetas T. C. 
Published: December 2004

AbstractFerromagnetic alloys, used in the form of „thermoseeds”︁ for surgical implantation, have been developed and used to induce localized hyperthermia in cancerous growths. Alloys of nickel with approx. 4 wt.% Si were chosen for this study because they have Curie temperatures in the desired range of 45–60°C. The thermoseeds were prepared by using either a special casting technique or casting and swaging followed by homogenization. The effects of these different processing schedules on the magnetic behavior of these alloys are discussed. In particular, the importance of minimizing oxidation during melting and heat treating, and the effects of homogenizing the thermoseeds on the relative permeability at temperatures near the Curie temperature are pointed out. The best processing schedule is casting small ingots while avoiding oxidation, followed by swaging, drawing, and homogenization. Actual induction heating experiments and the results from magnetization tests indicate that Ni‐4 wt.% Si alloys prepared in this manner can be used as thermoseeds with predictable Curie temperatures. These thermoseeds can be used to obtain nearly uniform and constant temperatures in tumors with variable blood flows.
In vitroandin vivometal ion release
Authors: Brown Stanley A. , Farnsworth Lilian J. , Merritt Katharine , Crowe Timothy D. 
Published: December 2004

AbstractA series of experiments was conducted to studyin vitroandin vivometal ion release and the urine excretion of metal ions. Metal salts were injected and urine analyzed. Anodic potentials were applied to stainless steel and cobalt‐chromium‐molybdenum (CCM) specimens to cause an acceleration of corrosion rates. Corrosion experiments were done in saline, 10% serum and in a subcutaneous space in hamsters. Corrosion rates were determined by measurements of weight loss and calculations of net charge transfer. Metal ion concentrations were determined with graphite furnace atomic absorption spectroscopy, and were calculated from total charge using Faraday's law. The results with stainless steel showed that the weight loss and metal ion release from stainless steelin vitroandin vivocan be calculated using Faraday's Law, assuming release in proportion to alloy composition. The results with CCM indicated that release ratesin vitrocan be used to determine the proportionality of releasein vivo. All the nickel and most of the cobalt was rapidly excreted, while less than 50% of the chromium was excreted. The excretion of metals following salt injection orin vivocorrosion were very similar.
Cell adhesion to a series of hydrophili–hydrophobic copolymers studies with a spinning disc apparatus
Authors: Horbett T. A. , Waldburger J. J. , Ratner B. D. , Hoffman A. S. 
Published: December 2004

AbstractAdhesion of cells to substrates strongly influences many of their functions and therefore plays an important role in a variety of processes, including phagocytosis, hemostasis, and the response of tissue to implanted materials. In previous studies, the influence of substrate hydrophilicity on cell adhesion has not been separated from effects due to major differences in other properties of the substrate, such as charge, rigidity, and the specific chemical composition of the materials. In addition, very few careful studies of the force required for cell detachment from various substrates have been performed. In this study, 3T3 cell detachment from a chemically homologous series of copolymers based on hydroxyethylmethacrylate (HEMA) and ethylmethacrylate (EMA) was measured with a spinning‐disc apparatus. The spinning‐disc technique allowed measurements of cell detachment over a wide range of applied shear stress on each sample. Cell detachment did not occur until a critical value of shear stress was exceeded. The critical shear stress of detachment decreased linearly with increasing HEMA content, from 18 dynes/cm2 on poly‐EMA to 0 on the polymers containing 83% or more HEMA. “Plating efficiency,” calculated as the fraction of cells initially applied which remained after dip rinsing the surfaces, did not vary significantly among most of the copolymers. Dip rinsing, however, exposes the cells to only one, relatively low shear stress (estimated to be somewhat less than 3 dynes/cm2). The existence of a critical shear stress for 3T3 cell detachment suggests that cell adhesion to surfaces cannot be fully understood with single shear stress methods because cells may attach with a wide range of strengths which are either all above or all below the applied shear stress. The influence of surface hydrophilicity on cell adhesion and the variety of forces which may contribute to this phenomenon are discussed.
Preparation and properties of a biomaterial: HEMA grafted SBS by γ‐ray irradiation
Authors: Hsiue Ging‐Ho , Yang Jen‐Ming , Wu Ryh‐Lih 
Published: December 2004

AbstractSolvent‐cast films of styrene‐butadienestyrene triblock copolymer (SBS) were synthesized and a poly(2‐hydroxyethylmethacrylate) (PHEMA) layer was grafted onto these films using Co 60 γ‐ray irradiation. The IR absorption spectrum of the graft copolymer was taken and its surface morphology studied by a scanning electron microscope. The degree of grafting and the mechanical properties of SBS, SBS‐g‐HEMA, and PHEMA were measured. In order to study its biocompatibility, contact angle and blood clotting time experiments were performed. The degree of grafting was related to the soaking time, film thickness and total irradiation dosage. However, it levelled off at 7% when the total dosage reacehed 1 Mrad. It was found that the mechanical properties of SBS‐G‐HEMA were the same as those of SBS and were superior to those of PHEMA. The blood compatibility of SBS‐g‐HEMA as measured by the Lee‐White clotting test was better than that of SBS and polystyrene and was quite similar to that of PHEMA.
Biocompatibility of six elastomers in vitro
Authors: Bakker D. , van Blitterswijk C. A. , Daems W. Th. , Grote J. J. 
Published: December 2004

AbstractThe biocompatibility of two silicone rubbers, Silastic and Dow Corning Elastomer, and of a polyether and a polyester urethane, a polyether polyester copolymer, and polypropylene oxide was assessed in vitro. These elastomers were selected for assessment as a possible alloplastic tympanic membrane. For these studies use was made of rat middle ear mucosa explants and serially cultured epithelium. The quantitative results were based on epithelial growth curves, the morphological picture was based on the findings in epithelium, and the aging of a biomaterial was simulated. Epithelium morphology was investigated by scanning and transmission electron microscopy and x‐ray microanalysis. Quantitative results showed that on Dow Corning Elastomer and polypropylene oxide, cell proliferation was significantly lower compared to normal growth curves. The morphological findings were negative for polypropylene oxide, and did not discriminate between the other biomaterials under study. The simulation results indicated better biocompatibility for the polyurethanes and the polyether polyester copolymer compared with that of polypropylene oxide and both silicone rubbers. Under the simulation conditions, cells exposed to Silastic showed siliconcontaining inclusions. These in vitro results suggest that the biocompatibility of the polyurethanes and the polyether polyester copolymer is better than that of both silicone rubbers and polypropylene oxide.
Effects of a grooved epoxy substratum on epithelial cell behavior in vitro and in vivo
Authors: Chehroudi B. , Gould T. R. , Brunette D. M. 
Published: December 2004

AbstractThe effects of grooved epoxy substrata on epithelial (E) cell behavior were studied in vitro and in vivo. V‐shaped grooves, 10 μm deep, were produced in silicon wafers by micromachining, a process which was developed for the fabrication of microelectronic components. The grooved substrata were replicated in epoxy resin. More E cells attached to grooved surfaces than to adjacent smooth surfaces. Clusters of E cells were markedly oriented by the grooved surfaces in comparison to the adjacent smooth surfaces where the orientation was random. Grooved and smooth epoxy implants were placed percutaneously in the parietal area of rats. One week after implantation E cells were found to adhere tightly to the implant surfaces. In the grooved portion of the implant E cells interdigitated into the grooves and had rounded nuclei. Histomorphometric measurements indicated that there was a shorter length of epithelial attachment and a longer length of connective tissue attachment in the grooved, compared to the smooth, portion of implants. After 10 days the epithelial attachment had migrated down the length of the protruding smooth portion of the implant and was located on the base of the implant. However, epithelium remained attached to the grooved portion of the implant. These observations indicate that grooved surfaces have the potential to impede epithelial downgrowth on percutaneous devices.
Colonization of n‐butyl‐2‐cyanoacrylate tissue adhesive by Staphylococcus epidermidis
Authors: Olson Merle E. , Ruseska Ivanka , Costerton J. William 
Published: December 2004

AbstractIn vitro adhesion of Staphylococcus epidermidis to cyanoacrylate tissue adhesive surfaces was investigated by employing a modified Robbins device. Bacterial colonization of n‐butyl‐2‐cyanoacrylate tissue adhesive polymer surfaces was demonstrated by employing scanning electron microscopy, epifluorescence technique, and aerobic plate counts. The S. epidermidis was found to rapidly colonize the n‐butyl‐2‐cyanoacrylate polymer surface producing a biofilm composed of embedded bacteria in an extensive amorphous matrix that totally occludes the material surface. The results indicate that the bacteriocidal properties of the polymer to this bacteria are weak or absent.
The corrosion fatigue properties of surgical implants in a living body
Authors: Morita Masafumi , Sasada Tadashi , Hayashi Hitoshi , Tsukamoto Yukio 
Published: December 2004

AbstractFatigue fracture of artificial implants in the human body, caused by the repeated application of stress, is well documented. It is known that the fatigue strength of implant materials decreases when they are exposed under in vivo corrosion conditions. There are, however, no investigations concerning the effect of body fluids on the fatigue characteristics of commonly used biomaterials. Accordingly, fatigue tests on machined stainless‐steel AISI 316, and COP alloy rods have been conducted in the right lower leg of rabbit. These specimens were piereced through the hole drilled at the middle of the tibial bone. A cyclic tensile stress of frequency 5 or 10 Hz was applied to the rods. From the results, it was found that the fatigue strength at 5 × 106 cycles for AISI 316 under the in vivo environment was 680 MPa compared to 830 MPa in air and similarly for COP alloy, was 680 MPa in the living body compared to 800 MPa in air. These remarkable changes in fatigue strength associated with the in vivo environments are considered to be due to the corrosive action of body fluids on the biomaterials.
Serotonin and β‐thromboglobulin release reaction from platelet as triggered by interaction with polypeptide derivatives
Authors: Kang Inn‐Kyu , Ito Yoshihiro , Sisido Masahiko , Imanishi Yukio 
Published: December 2004

AbstractThe effect of wettability of 14 polypeptide derivatives upon adhesion and activation of platelets was investigated with reference to release reactions from adhered platelets, using radioisotope labeling and radio‐immunoassay method. The serotonin release was more significant from platelets adhered to polymer materials to which a large number of platelets are adhered. However, no clear relationship was found between adhesion of platelets and β‐thromboglobulin release from adhered platelets. Therefore, stimuli inducing serotonin release and β‐thromboglobulin release were considered to be from different origins. The trend in β‐thromboglobulin release was well correlated with the extent of morphological change of adhered platelets as observed by scanning electron microscope. It was suggested that the determination of released β‐thromboglobulin in association with the measurement of platelet adhesion could be useful for evaluation of blood compatibility of materials.
Development of a new system for evaluating the biocompatibility of implant materials using an osteogenic cell line (MC3T3‐E1)
Authors: Itakura Yoshinobu , Kosugi Arihito , Sudo Hiroko , Yamamoto Shigehisa , Kumegawa Masayoshi 
Published: December 2004

AbstractA new culture system was developed to clarify the biocompatibility of implant materials with bone tissue using the MC3T3‐E1 osteogenic cell line. The cells were inoculated onto specimens such as aluminium oxide, titanium, dental casting silverpalladium alloy (PD), and a plastic coverslip. To study the effects of these materials on cell growth, differentiation, and calcification, DNA and protein content, alkaline phosphatase activity, and calcium content, respectively, were determined. The results from biochemical analysis suggest titanium and aluminium oxide to have adequate biocompatibility, while PD has an irritant effect on cell metabolism. It is clear that an objective view of the differentiation and calcification processes of osteogenic cells can be understood through such analysis. From the results of this study, our culture system appears suitable for evaluating the biocompatibility of implant materials with bone tissue.
Human monocyte/macrophage activation and interleukin 1 generation by biomedical polymers
Authors: Miller K. M. , Anderson J. M. 
Published: December 2004

AbstractIn vitro cell culture techniques were used to evaluate the effect of several clinically significant biomedical polymers on monocyte activation and Interleukin 1 (IL1) production. Isolated human peripheral blood monocytes were cultured in the presence of a panel of five biomedical polymers routinely used in a variety of clinical applications: Polyethylene (PE), silica‐free polydimethylsiloxane (PDMS), woven Dacron fabric, expanded polytetrafluoroethylene (ePTFE) and the segmented polyurethane, Biomer. Monocytes generated IL1 in the presence of all five materials. Maximal levels of IL1 were generated at 24 h in monocyte‐polymer cultures supplemented with serum and additionally stimulated with lipopolysaccharide (LPS). No difference was observed due to serum source. Results from cultures supplemented with fetal bovine serum were not significantly different from those obtained with human serum supplemented cultures. The thymocyte proliferative activity generated by monocytes in the presence of these biomedical polymers was neutralized by a specific polyclonal anti‐IL1 antiserum. Statistically significant differences in IL1 production were observed between polymers, allowing their classification according to reactivity into high (Dacron, PE), intermediate (ePTFE) and low (Biomer, PDMS) reactive groups.
Effect of particle size on the in vitro and in vivo degradation rates of poly(DL‐lactide‐co‐glycolide) microcapsules
Authors: Visscher G. E. , Pearson J. E. , Fong J. W. , Argentieri G. J. , Robison R. L. , Maulding H. V. 
Published: December 2004

AbstractThree different sieve size fractions of ergotcontaining biodegradable microcapsules were examined both in vitro and in vivo. The sieve sizes and average particle diameter, (μm), were: less than 45–75 (X̄ = 30); 75–106 (X̄ = 79), 106–177 (X̄ = 130). These microcapsules contained ca. 9% drug and were produced from 50:50 poly(DL‐lactide‐co‐glycolide). The objective was to determine the effect of particle size on in vivo and in vitro degradation rates. The microcapsules were injected into rat gastrocnemius muscle and excised and examined at various time points up to 70 days. Initially a minimal tissue response was noted which was characterized by a sharply localized acute inflammatory reaction. Following this, connective tissue and foreign body giant cells engulfed the microcapsules at 20–30 days. Only vestiges of the microcapsules were found surrounded by minimal connective tissue and foreign body giant cells after 60–70 days. The tissue reaction was a minimal, sharply localized foreign body giant cell and connective tissue process for all three size groups of microcapsules. The largest microcapsules (X̄ = 130 μm) exhibited a slightly greater tendency to undergo in vivo and in vitro degradation relative to the other groups. However, it can be concluded that over the microcapsule size ranges examined minimal differences in the degradation properties of the polymeric matrices and consequently those of the microcapsules were noted.
Experimental implantation of hydrogel into the bone
Authors: Korbelář P. , Vacík J. , Dylevský I. 
Published: December 2004

AbstractThe present study deals with the application and possibilities of insoluble hydrophilic gels (poly(2‐hydroxyethyl methacrylate)) as substitutes of bone tissue experimentally. Their biocompatibility is examined with regard to the porous qualities of the implant and to its chemical structure, and their behavior in the cancellous and compact bone is evaluated. It was found that the modifications of hydrogels used in the experiment are biocompatible, with the compatibility increasing in proportion to increasing porosity. The nonporous and microporous hydrogels are not compatible and are demarcated. The sintered macroporous gel is surrounded by a thin fibrin membrane. By adding methacrylic acid to the hydrogel surface, adhesion increases markedly. Marked destruction also appears in the polymer especially in the cancellous bone. By an active destruction of the polymer, no direct phagocytosis can be proved. Upon breakdown of the implant in the compact bone the activity of the macrophages is delayed. When the gel without methacrylic acid is used alone, destruction does not occur even after 193 days. When methacrylic acid is added to the polymer surface, destruction does occur and the implant is filled only by bone trabeculae.