bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thrombogenicity of different suture materials as revealed by scanning electron microscopy
Authors: Dahlke Hermann , Dociu Nicolae , Thurau Karla 
Published: December 2004

AbstractThe thrombogenicity of five suture materials—polypropylene (Prolene), polyester (Mersilene), polyglactin 910 (Vicryl), nylon (Ethilon), and silk—was examined in vivo by scanning electron microscopy. The most blood‐compatible material appeared to be Prolene. A rather satisfactory antithrombogenciity was shown by Mersilene, in comparison with which Ethilon and Vicryl provided less thromboresistance. The possible connection between the chemical changes which occur during the hydrolysis of Vicryl and its blood compatibility is discussed. Of the tested materials, silk proved to be the most thrombogenic. This study shows that the thrombogenicity of a suture material could be easily and conveniently tested in an experimental model by scanning electron microscopy, thus enabling the first choice of a suitable suture for the cardiovascular surgery, before one continues with other more sophisticated methods for the evaluation of thromboresistance.
Biophysical evaluation of the tumorigenic response to implanted polymers
Authors: Habal Mutaz B. , Powell Rodger D. 
Published: December 2004

AbstractAn evaluation of the biophysical changes of methylcholanthrene induced tumor (M4) in laboratory animals receiving four different alloplastic implants was conducted. The implants are silicone, polyether urethane, poly(methyl methacrylate), and bioglass. The tumor was allowed to grow to a large size in 28 days and then removed by shelling it from the surrounding tissue. Three different analytic volumetric measurements were carried; size in cm3, volume in milliliters and weight in grams. Statistical analysis on the three different analytic measurements did not disclose any significant differences in tumor growth potential between the control and the experimental groups. We conclude that in this study we were unable to demonstrate any tumor “facilitation” effect by any of the implantable polymers used. Therefore, there is no contraindication in using the polymers to reconstruct defects produced by cancer ablative procedures.
Interaction of the absorbable hemostatic agent (IP760) with aminoglycosidic antibiotics
Authors: James Boyle V. 
Published: December 2004

AbstractThe linear, crosslinked amylose‐succinate hemostatic agent, IP760, has been evaluated for its interaction with aminoglycosidic antibiotics. The highly structured polymer appears to act as a cationic exchange resin which binds the basic aminoglycosides. Binding of these agents to IP760 is reversed by increased pH and/or increased ionic strength. Dialysis experiments demonstrated that 85 and 90% of the bound gentamicin was released at pH 7.5 and 8.0, respectively, over a period of 36 hr. Formation of the IP760‐antibiotic complexes suggests potential medicinal use for hemostasis and slow release of the antibiotic for prophylaxis of postsurgical contamination or infection.
The influence of electropolishing on the corrosion resistance of 316L stainless steel
Authors: Sutow Elliott J. 
Published: December 2004

AbstractA study was conducted which examined the influence of electropolishing on the corrosion resistance of a cold rolled 316L stainless steel. Test specimens were surface prepared to a final mechanical finish of wetted 600 grit SiC paper, prior to electropolishing. An oH3PO4/Glycerol/H2O electropolishing solution was employed for times of 15, 20, and 25 min. Control specimens were surface prepared only to the final mechanical finish. Anodic polarization tests were performed in a deaerated Ringer's solution (37°C) which was acidified to pH 1, with HCl. The electropolished specimens demonstrated increased corrosion resistance, when compared to the control specimens. This was evidenced for the former by more anodic corrosion and breakdown potentials, and the absence of a dissolution peak which was observed for the control specimens at the initial polarization potentials. Surface hardness measurements indicated that this increase in corrosion resistance was produced, in part, by the removal of the cold worked surface layer produced by the mechanical finish. In terms of increasing corrosion resistance, no optimum electropolishing time was found within the 15–25 min treatment period.
The anchoring of glass ceramics of different solubility in the femur of the rat
Authors: Gross U. M. , Strunz V. 
Published: December 2004

AbstractA direct physicochemical bond between alkali‐rich bioglass or glass ceramic (45 S 5 A and B, Hench) or alkali‐poor glass ceramic (KG S, Brömer) and bone has been well documented. Since long‐term studies have revealed the interface to be subjected to remodeling of the bone and to increased focal disintegration of the implant, glass ceramics of reduced solubility have been developed by lowering the Na2O content and adding Al2O3, Ta2O5, TiO2, and Sb2O3. Implants of glass ceramic KG S and different compositions with reduced solubility have been studied histologically 14, 29, or 30, 60, 119, and 245 days after implantation in the femur of male Sprague‐Dawley rats. Implants of KG S are anchored at an interface with bone connection, which is known to provide for application of considerable shear and tensile strengths; whereas, at the interface of ceramics of reduced solubility, soft tissue, chondroid and osteoid are mainly observed. The dynamics of the events at the interface indicate a disturbance of the transformation of chondroid cells into osteoblasts and of the mineralization of osteold. This disturbance of pathophysiologic processes during bone healing or bone regeneration is discussed.
An investigation of the bacteriostatic properties of pure metals
Authors: Bundy K. J. , Butler M. F. , Hochman R. F. 
Published: December 2004

AbstractThe effect of 16 pure metals on the in vitro growth of a form of dental caries producing Streptococcus mutans was studied under both aerobic and anaerobic conditions. Cobalt and copper were consistently observed to be inhibitory. With less consistency nickel, titanium, iron, and vanadium also exhibited ability to inhibit growth of the organism. Bacteriostasis apparently is contingent upon the presence of a corrosion process. The bacteriostatic agent is of uncertain identity and could be a corrosion product or a process secondary to the occurrence of corrosion. Concentrations of metals after 6 days of electrochemical dissolution in the growth medium were measured via electron microprobe analysis and compared with the amount of inhibition which resulted. Threshold concentrations above which growth did not occur were identified. As measured by threshold concentrations, wide variability between metals exists in the ability to inhibit the growth, with cobalt being particularly effective at small concentrations. This implies a sensitivity on the part of the organism that is different for different metals. The threshold concentration varied between aerobic and anaerobic conditions. Streptococcus mutans appeared more resistant to the effects of the metals under anaerobic conditions even though little difference in the amount of corrosion was detected.
Time‐dependent failure of a polyolefin rubber candidate material for blood pump applications
Authors: McKenna G. B. , Penn R. W. 
Published: December 2004

AbstractFailure behavior of a polyolefin elastomer which is a candidate material for blood pump applications has been studied under uniaxial and equibiaxial test conditions. Both static and dynamic (fatigue) testing were performed to study four aspects of material failure behavior as suggested by a cumulative damage failure model. Results from testing a standard formulation butyl rubber are presented for comparison. Our results show that the uniaxial failure behavior under static loads for the butyl rubber is superior to that of the polyolefin rubber at high loads but that the polyolefin is superior at low loads. Under fatigue loading conditions, the failure times for both rubbers decrease with increasing test frequency. The observed frequency dependence lies between that predicted by the cumulative damage model and that predicted by a cycle dependent fatigue model. The distribution of failure times for the polyolefin rubber is broader than that for the butyl rubber. For both uniaxial and equibiaxial testing, the distribution of failure times changes in going from the static testing to dynamic testing. This is true for both rubbers.
Interaction of some serum proteins with hydroxylapatite and other materials
Authors: Klein C. P. A. T. , de Groot K. , Vermeiden J. P. W. , van Kamp G. 
Published: December 2004

AbstractIn order to investigate whether the immune system is involved in the degradation of hydroxylapatite as implant material the adsorption behavior of several serum proteins to hydroxylapatite was studied and compared with the adsorption to other calcium phosphate compounds (Ca3(PO4)2, CaHPO4), calcium carbonate, aluminium oxide, and zinc oxide. It was found that complement factors, C4 and C3, and α2‐HS‐glycoprotein adsorbed to the calcium phosphate compounds, but not to the other materials. IgG and albumin were adsorbed to all investigated compounds. These results suggest that the complement factors are directly adsorbed on the surface of the calcium phosphate compounds. Therefore, the activation of complement, if any, proceeds by the classical pathway. The binding of complement factors to the calcium phosphate salts investigated points to a more specific involvement of the immunosystem in the degradation process of calcium phosphate implants.
The elastic modulus of soft denture liners
Authors: Ellis Bryan , Lamb D. J. , Al‐Nakash Suad 
Published: December 2004

AbstractUnder certain circumstances, e.g., when treating “denture sore mouth” or after the provision of immediate dentures, dentures may be lined with soft rubberlike materials which have Young's moduli within the range ≃105 N m−2. Measurement of the compression modulus Ec of such soft liners is described and Gent and Lindley's method of calculating Young's modulus E was evaluated. It was established that the Young's modulus may be calculated using: Ec = E(1 + 2kS2), where k = 1 for soft rubbers, and for disks S is a shape factor and = radius/2 × thickness. It is also shown that Young's modulus is a linear function of log(rate of strain) for both tension and compression measurements. When gellation has occurred subsequent to mixing there is an increase in Young's modulus due to loss of ethanol. When immersed in brine the elastic modulus remains approximately constant from a day to a week or longer.
Biological effects of residual glutaraldehyde in glutaraldehyde‐tanned collagen biomaterials
Authors: Speer Donald P. , Chvapil Milos , Eskelson C. D. , Ulreich Judith 
Published: December 2004

AbstractGlutaraldehyde is commonly used to control physical and biological properties of collagen structure by means of intramolecular and/or intermolecular crosslinking of collagen molecules. Solubility, antigenicity, and biodegradation of naturally occurring or reconstituted collagenous matrices are effectively reduced by glutaraldehyde treatment. Adverse biological reactions to glutaraldehyde have been limited to infrequent contact dermatitis and to biocidal effects which are exploited in chemical sterilization media. In the present study of glutaraldehyde‐tanned collagen sponge, the presence of glutaraldehyde was correlated with cytotoxic effects upon fibroblasts in tissue culture and foreign body giant cell reaction to bioimplants of the sponge. Fibroblast growth in tissue culture is 99% inhibited at media concentrations of 3.0 ppm glutaraldehyde. Extracts of glutaraldehyde collagen sponge in aqueous media at pH 7 and 4.5 yielded 6 μg and 65 μg glutaraldehyde per gram of collagen sponge, respectively. The yield increased tenfold at pH 4.5. Observations indicate that leaching of the glutaraldehyde from glutaraldehyde‐tanned collagen sponge is sufficient to produce potentially adverse cellular effects both in vivo and in vitro.
Detection of aluminum oxide and polyethylene wear particles from joint endoprostheses using cathodoluminescence and x‐ray analysis in SEM
Authors: Roschger P. , Hoerl E. M. , Stachelberger H. , Plenk H. 
Published: December 2004

AbstractA highly sensitive method to localize aluminum oxide or polyethylene wear particles in biological tissues is presented. Using the scanning electron microscope (SEM) with a special cathodoluminescence detector system, small amounts of these foreign materials can be visualized in simple frozen sections by their bright luminescence, even at low magnifications (200X). At higher magnifications, a differentiation of free as well as phagocytized aluminum oxide and polyethylene particles can be made due to their different behavior in light emission. In addition, aluminum oxide such as other metals can be identified by x‐ray microprobe analysis. This combination of SEM with microprobe analysis and with the highly sensitive cathodoluminescence mode enables to detect and identify wear products from all the materials, commonly used in manufacturing artificial joint replacements.
Gelatin‐based sprayable foam as a skin substitute
Authors: Neumann P. M. , Zur B. , Ehrenreich Y. 
Published: December 2004

AbstractPhysical and antimicrobial properties of a newly developed gelatin based spray‐on foam bandage for use on skin wounds have been evaluated. The aqueous foam is sprayed from aerosol containers and effectively covers and washes uneven wound surfaces. The foam dries to form an adherent and stable three‐dimensional matrix which diminishes evaporative water losses. The foam possesses antimicrobial activity against gram‐positive, gram‐negative, and fungal contaminants.
An in‐vitro study of the effect of buffer on the degradation of poly(glycolic acid) sutures
Authors: Chu C. C. 
Published: December 2004

AbstractThe tensile strengths of poly(glycolic acid) (PGA) sutures immersed in buffered and unbuffered aqueous media were compared. The media used were an unbuffered physiological saline solution (pH = 5.0) and a phosphate‐buffered physiological saline solution (pH = 7.4). PGA samples were immersed for various periods in each medium, and kept at 37 ± 1°C in a constant temperature oven. The tensile strengths of the specimens were tested immediately after removal from the medium. Stress‐strain curves of the specimens were expressed in terms of the stress unit “tenacity,” commonly used in the study of fibrous polymers; it is an appropriate unit for materials of fibrous nature. These stress‐strain curves were investigated as functions of buffering and duration of immersion. Degradation reduced the tensile strength of PGA more in the buffered saline solution than in the unbuffered. This higher rate of degradation in the buffered solution might be due to the presence of Na2HPO4, which removed the degradation products, shifted the reaction toward increased hydrolosis, and accelerated the loss of tensile strength in the PGA. A continuous decrease in the pH of the unbuffered solution supports this explanation. Tied‐chain segments of macromolecules, a theory widely used in the study of mechanical strength of fibrous polymer may be the key to a comprehensive description of the degradation phenomenon of PGA.
Fixation of porous titanium implants in cortical bone enhanced by electrical stimulation
Authors: Colella S. M. , Miller A. G. , Stang R. G. , Stoebe T. G. , Spengler D. M. 
Published: December 2004

AbstractThe effect of in vivo electrical stimulation on the interfacial strength between porous titanium implants and cortical bone was studied in mongrel dogs. The interfacial shear strength of the stimulated implants was consistently greater than that of controls. No difference could be observed in the quality of bone ingrowth. The data suggest that the rate and quantity of bone ingrowth were enhanced by electrical stimulation.
Biocompatibility of echinoderm skeleton with mammalian cells in vitro: Preliminary evidence
Authors: Fontaine A. R. , Hall B. D. 
Published: December 2004

AbstractThe physical and chemical properties of echinoderm skeleton are reviewed. A method is described for preparing cell‐free, sterile echinoderm skeletal plates (ossicles) which were used as porous substrates for cell cultures. Ossicles of the starfish Pisaster ochraceus were evaluated as substrates for the culture of three mammalian cell lines. Each line grew vigorously on ossicles, and fibroblasts quickly infiltrated their porous microstructure. Echinoderm skeletal plates provide a simple, convenient alternative to coverslips and porous membranes for SEM or correlated SEM/TEM studies of cell behavior. More importantly, the preliminary evidence for biocompatibility presented suggests that native echinoderm skeleton has potential use as a biomaterial and, because of its microstructure and relative solubility; deserves evaluation as a kind of biodegradable ceramic.
Age‐hardening and tensile properties of low gold (10–14 kt.) alloys
Authors: Kusy R. P. , Leinfelder K. F. 
Published: December 2004

AbstractThe age‐hardening and tensile properties were determined for seven 10–14 kt. gold alloys, a conventional type II, and a sterling silver alloy. For the low‐gold alloys the heat hardening curves indicated that the maximum aging effects were attained after 30 min at 400°C. From tensile tests on either wire or dumbbell specimen configurations, Young's modulus (E), proportional limit (P.L.), ultimate tensile strength (U.T.S.), and elongation to break were measured for alloys in both the solution annealed (S) and the hardened (H) state. These stress‐strain data not only confirmed previous correlations noted for conventional gold alloys between either E, P.L., or U.T.S. and hardness and between U.T.S. and P.L., but also varied systematically with the Au/Cu ratios in the (H) state. Under identical heat treatment and tensile testing conditions, comparison of the manufacturers' cast samples with this laboratory's specimens showed that, while the E, P.L., and U.T.S. differed somewhat, the greatest change occurred in the elongation to break. Here after measuring the porosity of the different specimen configurations and analyzing the log10 elongation with VHN, the conclusion was clear: Specimen geometry markedly influenced the physical properties. On this basis the proposed dumbbell geometry is advocated over the wire specimen configuration currently cited in ADA Specification No. 5.
Corrosion fatigue of surgical stainless steel in synthetic physiological solution
Authors: Cahoon J. R. , Holte Richard N. 
Published: December 2004

AbstractFatigue tests conducted both in air and synthetic physiological solution show that the fatigue strength of surgical stainless steel in synthetic physiological solution is about 10% lower than the strength in air for a given endurance level. It is proposed that surgical stainless steel which is normally passive in physiological solution suffers corrosion fatigue because of susceptibility to crevice corrosion which occurs at extrusions and intrusions (crevices) on the surface thereby shortening the crack initiation time and the fatigue life.
Mechanical properties of model synthetic tendons
Authors: Kolařík J. , Migliaresi C. , Štol M. , Nicolais L. 
Published: December 2004

AbstractModel synthetic tendons consisting of 20 vol % of texturized poly(ethylene terephthalate) fibers and of the water‐swollen poly(2‐hydroxyethyl methacrylate) matrix have the tensile modulus E = 1.5 ± 0.1 GPa, strength and strain‐at‐break σb = 85 ± 10 MPa and ϵb = 0.08 ± 0.02. The force required for breaking tendons with the diameters 2, 3, 4 mm is, respectively, 300, 500, and 960 N. By these properties model synthetic tendons closely imitate the properties of natural tendons. Long‐term (100 min) and repeated short‐term (30 times 1 min) creep shows that on loading model tendons lose some 10% of their stiffness, but that the whole deformation is reversible. The shape of the compliance vs. time dependence of synthetic tendons closely resembles the dependence determined for the parent fiber. The stiffness and strength of a tendon are given by those of the fiber bundle used; by varying fiber volume fraction, it is possible to adjust the required mechanical properties of tendons.
In vitro corrosion and tarnish characterization of typical dental gold compositions
Authors: Vaidyanathan T. K. , Prasad A. 
Published: December 2004

AbstractAnalysis of the anodic polarization and alternate immersion test response of 16 precious metal alloys with compositions similar to those of commercial dental golds indicate that alloys containing high (Ag + Cu) contents are likely to be more corrosion and tarnish prone. It also appears that the alloys containing high precious metals contents (Au, Pt, and Pd) are characterized by immunity or anodic film protection over a range of anodic overpotentials, indicating superior corrosion resistance.
Biochemical, histological, and ultrastructural assessments of pseudoneointimal linings derived from fibroblast‐seeded integrally textured polymeric surfaces
Authors: Szycher M. , Poirier V. , Franzblau C. , Faris B. , Snider R. , Toselli P. , Haudenschild C. C. , Bernhard W. F. 
Published: December 2004

AbstractA new technique has been employed for producing Model 11 Biomer bladders with integrally textured blood‐contacting surfaces. For the past year, we have been routinely fabricating integrally textured polymeric surfaces from negative‐replica silicone molds, which are a high‐fidelity facsimile of conventionally flocked bladders. The objectives of this investigation are threefold: (1) To develop a blood‐contacting surface that promotes the formation of a stable pseudoneointimal lining; (2) to investigate means of accelerating replacement of initial fibrin coagulum by a collagenous lining; and (3) to characterize the resultant pseudoneointimal lining biochemically, histologically, and ultrastructurally. Systematic in vivo studies were undertaken to evaluate the new surface in terms of its ability to form a thin, stable, biologic lining. Control experiments were carried out to compare results with previous experience utilizing polyester fibril flocked surfaces. Additional studies were conducted to define the effects of cell seeding of integrally textured surfaces. A total of 16 experiments have been conducted to date; eight bladders were seeded with allogeneic fetal cells prior to implantation and eight bladders were unseeded, to serve as controls. In vivo trials of seeded surfaces have resulted in the formation of strong, cellular, and highly collagenous linings, with collagen contents varying between 31% and 65%. These linings contain viable cells and thus exhibit high cellular activity, as evidenced by postexplant cell culture techniques. This indicates that a living, viable pseudoneointima has been generated. On the other hand, control (nonseeded) linings do not produce significant amounts of collagen in their linings.
Biocompatibility of polymeric delivery systems for macromolecules
Authors: Langer Robert , Brem Henry , Tapper David 
Published: December 2004

AbstractWe previously reported the use of polymeric delivery systems capable of sustained release of substances with molecular weights up to 2 × 106. The current study examined the tissue compatibilities of these slow‐release agents and of other polymeric materials. To observe in vivo host responses to specific implants, tests were conducted in the rabbit cornea. The cornea as an implant site has several advantages compared to other organs including its clarity, avascularity, sensitivity, and convenient access to view. Corneas were examined using stereomicroscopy and histology. Two polymers suitable for sustained macromolecular release, poly(hydroxyethyl methacrylate), and alcohol‐washed ethylene‐vinyl acetate copolymer, were noninflammatory. Other polymers considered for sustained macromolecular release, such as polyacrylamide and poly(vinyl pyrrolidone), produced significant inflammation.