bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of the mocroprobe analyzer to biological materials investigations
Authors: Domagala Robert F. , Van Thyne Ray J. , Lenke John W. 
Published: May 2005

AbstractThe microprobe analyzer has proved to be a valuable tool in investigation of dental and medical materials problems, and the results of a number of studies are described. Interesting aspects of the amalgam–tooth interface have been examined and dental calculus compostion has been determined. Surgical implant studies have included evaluation of appliance alloys and failure analysis of surgical devices.
Correlation of microstructures and open‐circuit potentials of gold–iron alloys with their in‐vivo corrosion behavior
Authors: Acharya Abhijit , Sandrik J. L. , Wragg L. E. , Greener E. H. 
Published: May 2005

AbstractThe in vitro behavior of a number of Au–Fe precipitation‐hardenable alloys have been investigated in distilled water and in Ringer's solution (simulating the extracellular body fluids) by the open‐circuit potential versus time method. The in vivo behavior of these materials as muscle implants has been studied by conventional histopathological and histochemical techniques. Optical and electron microscopic techniques have been used to study the extent and morphology of massive discontinuous precipitation as well as the mode of corrosion attack. A clear correlation has been established between the microstructural features presented by a given alloy and the time‐dependent open‐circuit potential and in vivo corrosion behavior. It can be concluded for this alloy system that the microstructure and the open‐circuit potential pattern may be taken to be a reasonable indication of the expected in vivo corrosion behavior.
Adherence of prosthetic skin
Authors: Skornik William A. , Dressler Donal P. , Rhicard John K. 
Published: May 2005

AbstractRecently, a new successful prosthetic skin was reported from this laboratory. Utilizing the burned rat model, this prosthesis, controlled burn wound sepsis, prevented insensible water vapor loss and remained indefinitely. A prime factor necessary for the success of this prosthesis is its ability to adhere early to the recipient site. Thus, in order to investigate the underlying mechanisms of adherence and to be able to evaluate more closely different types of prosthetic skin, materials, and designs, a quantitative technique was developed using a modified Keil tester. The force (dynes/cm2) necessary to tear the prosthesis free was recorded on a direct writing apparatus. Tensile strength measurements of the prosthetic skin revealed a gradully increasing adherence of the tissue to the prosthesis. Initial values, days 2 through 5 post‐application, were low as recorded in dynes/cm2. The graft when removed on these days showed little or no gross fascial adherence, however, edge adherence steadily increased. After a few days the successful prosthesis could not be peeled without removing some tissue. Histologic studies show that by day 9 the prosthesis is an integral part of the subcutaneous tissue with foreign body giant cell reaction, ingrowth of of fibroblasts and collagen, and few inflammatory cells or bacteria. The adhesion values reveal that as the day post‐application increased the mean value in dynes/cm2 increased from an initial 2.137 on day 2 to 8.019 on day 50.
A heat‐transfer device for the monitoring of thrombus formation on prosthetic surfaces
Authors: Klopp Edward H. , Jacobs Lloyd A. , Topaz Stephen R. , Gott Vincent L. 
Published: May 2005

AbstractIn order to monitor changes in thrombus size on prosthetic surfaces in dogs, a simple heat transfer measuring system was incorporated into a small right atrial sword which has been previously described.1 This system provided a reliable and continuous measure of the amount of thrombus present on the sword. Initial thrombus formation was found to be complete within 45–90 min. Subsequent lysis of the thrombus was seem to occur in many cases after 8–12 hr of implantation.
Direct chemical bond of bioactive glass‐ceramic materials to bone and muscle
Authors: Hench L. L. , Paschall H. A. 
Published: May 2005

AbstractThe objective of this research is to achieve direct chemical bonding of structurally strong implant materials with hard and soft tissues. This objective has been achieved through the development of a series of surface‐active bioglasses and bioglass‐ceramics. A controlled release of Ca, P, and Na ions from the surface of the materials produces an alkaline pH and nutrient constituents at a time when the body can incorporate the ions into newly formed tissues. Optical and electron microscopy of in‐vivo implants in rat femurs and muscles show the development of stable chemically bonded physiological interfaces after 6 weeks. Microstructure and crystallinity of the materials do not influence the bonding achieved. Mechanical measurements of the bond strength in bone show that the bone fractures before the interface does. In‐vitro studies of protein epitaxy, hydroxyapatite crystallization, and solubility kinetics correlate with the proposed interfacial bonding theory.
The clinical experience with silicone‐Dacron metacarpophalangeal and interphalangeal joint prostheses
Authors: Goldner J. Leonard , Urbaniak James R. 
Published: May 2005

AbstractOur 4‐year clinical experience with reconstruction of worn metacarpo‐phalangeal and proximal interphalangeal joints with silicone‐Dacron prostheses in 121 patients is presented.Emphasis is on preoperative assessment and proper selection of patients.Three hundred sixty‐nine metacarpophalangeal joint prostheses and 27 proximal interphalangeal joint prostheses have been inserted. Most of the patients had rheumatoid arthritis; several had degenerative arthroses, and a few had traumatic arthrosis.Particular attention is directed to minor modification of surgical techniques and emphasis is on postoperative management. Suggestions for implant redesigning and modification are made.The silicone‐Dacron arthroplasties have been successful in decreasing pain, improving stability, increasing hand function, and in providing an adequate range of motion.Complications have included five infections, two recognized fractured prostheses, and two instances of early dislocation of a prosthesis. The patients have consistently been relieved of pain: on the basis of this short‐term experience, we believe that the implant principle in the hand is successful, but improvements in design and material are needed.
The role of stress‐enhanced reactivity in failure of orthopaedic implants
Authors: Rose R. M. , Paul I. L. , Weightman B. , Simon S. R. , Radin E. L. 
Published: May 2005

AbstractScanning electron micrographs were made of the surfaces of silicone rubber finger joint prostheses which had been subjected to 107bending cycles at 37°C in bovine serum. Preferential attack at the regions of highest stress and the formation of microcracks of length 10μ and less were observed. By way of analogy with the corrosion fatigue phenomenon in metallic alloys, it is suggested that these may be initiation sites for the mechanical failures which have been observed, and that the acceleration of lipid absorption by tensile stress provides potential mechanisms for both initiation and accelerated propagation of fatigue cracks. It is demonstrated as a consequence of mechanochemical thermodynamics that any constituent of the body fluids (e.g. lipids) which can swell the elastomer will in fact be preferentially absorbed at the point of highest tensile stress, i.e., the crack tip, and that swelling will be accelerated by the applications of tensile stress.
In vivo and in vitro changes in strength of orthopedic calcium aluminates
Authors: Schnittgrund G. D. , Kenner G. H. , Brown S. D. 
Published: May 2005

AbstractCalcium aluminate bars were formulated to study the effect of real and simulated biological environments on strength. Static fatigue tests revealed that the strength of these potential internal bone prostheses decreased to ca. 60% of their initial strength after less than 100 min while being held at constant stress in solution. Calcium aluminate bars aged for 12 weeks in water or Ringer solution were also found to exhibit large losses in strength, while bars implanted in vivo for the same period of time weakened somewhat less. Semi‐quantitative analysis of the solutions in which the calcium aluminate bars were aged revealed that Al3+ and Ca2+ were being leached from the bars in both the saline and water baths, while the concentration of Mg2+ was decreasing in the Ringer solution.Scanning electron microscope (SEM) studies revealed extensive microstructural changes in specimens aged in water or saline solution for 1 and 12 weeks. Similar but far less extensive changes were seen in bars aged in vivo in rabbits for 12 weeks.
Corrosion of the η′(Cu‐Sn) phase in dental amalgam
Authors: Marek M. , Okabe T. , Butts M. B. , Fairhurst C. W. 
Published: May 2005

AbstractPrevious studies have shown preferential corrosion of the η′(Cu‐Sn) phase in highcopper dental amalgam both in vitro and in vivo, while samples of pure η′ have shown high corrosion resistance. To clarify this contradiction, samples of pure η′ crystals mixed with other phases were prepared and tested. Evaluation of the corrosion resistance was based on the results of coulometry at constant potential and potentiodynamic polarization. The corrosion susceptibility of η′ in the matrix of γ(Ag‐Hg) was considerably higher than the susceptibility of isolated η′. The susceptibility of pure η′ also could be increased by plating it will small amounts of Hg. It was concluded that in dental amalgam, the presence of mercury in the phases surrounding η′ reduces its resistance to corrosion. Although η′ is more resistant to corrosion than γ2(Sn‐Hg) which appears in low‐copper amalgams, it is the least corrosion resistant major phase in high‐copper amalgams and can suffer deterioration.
The electro‐osmotic actuation of implantable insulin micropumps
Authors: Uhlig E. L. P. , Graydon W. F. , Zingg W. 
Published: May 2005

AbstractA study using an electro‐osmotic cell suitable for actuating an implantable insulin micropump showed that controlled variable flow rates in the order of 0.2 mL/day are possible. The cell functioned continuously with low energy and power requirements and long service life. The principle of operation is compatible with achieving the very low flow rates necessary if highly concentrated insulin is to be used to avoid frequent insulin reservoir refilling. An electro‐osmotic cell, Ag/ AgCl/NaCl(aq)/ cation exchange membrane/NaCl(aq)/ AgCl/ Ag, was connected to a constant current power supply which reversed the direction of the current every 10 mins causing a to‐and‐fro transport of fluid through the membrane. Flow rates of 0.15–0.60 μL/min were achieved with currents of 2.5–10 mA. At the low flow rate, energy consumption was 6.4 × 10−2 J/μL and peak power requirement was <2.0 × 10−4 W. Fluid was transported against a pressure gradient of 52 cm Hg. The cell contained a total electrolyte volume of <0.25 mL. The membrane showed no change in properties after 10,000 current reversals (69 days). To function as an actuator for an implantable insulin micropump, the electro‐osmotic cell requires a switching and valving assembly; a suitable design for this is briefly considered.
Grafted synthetic sorbents for enhanced removal of toxic chemical agents from plasma
Authors: McPhillips D. M. , Armer T. A. , Owen D. R. 
Published: May 2005

AbstractA series of porous polymeric sorbents and activated carbon were used to remove di‐isopropyl methylphosphonate (DIMP) from human plasma and normal saline. The sorptive capacities of the commercially available sorbents Amberlite XAD‐4, XAD‐2, XN1010, and XE348, and Calgon 400 were determined. Butyl‐ and palmityl‐grafted XAD‐4 were prepared with graft efficiencies of 32 and 6%, respectively, and tested for sorptive capacities. DIMP removal efficiencies were compared to dialysis with a 1.8 m2 Cordis‐Dow hollow fiber artificial kidney (HFAK). Butyl‐grafted XAD‐4 and active carbon outperformed the other sorbents in removing DIMP from both saline and plasma. An order of magnitude reduction in removal ability was noted for all the adsorbents when the mobile media was plasma. Pronounced plasma precipitation was elicited by activated carbon, an effect not observed with any of the polymeric resins tested. The removal efficiencies on a 18.0 g basis of XAD‐4, butyl‐grafted XAD‐4, and active carbon were comparable to that of the HFAK used in this study. These sorbents, however, possess a macroscopic surface area of approximately 0.1 m2, an order of magnitude lower than that of the HFAK. This reduction in contact area is believed to reduce substantially the possibility of undesirable molecular and cellular effects.
Histological investigation of bone induction by demineralized allogeneic bone matrix: A natural biomaterial for osseous reconstruction
Authors: Vandersteenhoven J. J. , Spector M. 
Published: May 2005

AbstractThe objective of the study was to delineate the histological sequence of events associated with bone formation induced in extraosseous sites by implants of demineralized allogeneic bone matrix (DABM) in order to provide a more complete basis for the clinical use of the natural biomaterial for osseous reconstruction. The rat was the experimental animal model. Implants were prepared by demineralization of diaphyseal cortical rat bone in 0.6N HCl for 18–24 h. A total of 104 specimens, 4 mm square, were implanted both subcutaneously and intramuscularly in 26 rats for periods of 3 days to 22 weeks. Histological evaluation revealed a sequence of events that at 3 days displayed an inflammatory response to surgical trauma and after 6 weeks exhibited the formation of a mature lamellar ossicle with central marrow which was maintained through 22 weeks. Resorption of the DABM, first evident at 1 week, was accompanied by the appearance of chondroblasts in vascular canals and in crevices in the implant. Osteoblastic activity, initially seen at 2 weeks, appeared to be associated with capillary and blood vessel formation around the implant and within enlarged resorptive cavities within the specimens. Calcification occurred in the cartilaginous matrix and osteoid and within the implanted matrix.The osteoinductive process comprises (1) the inflammation / granulation / scar formation processes elicited by implantation of a material, (2) the resorptive response elicited by DABM, and (3) the process of induction of nonosseous mesenchymal cells to differentiate to chondroblasts and osteoblasts. The results of the present study support previous investigations demonstrating the bone‐inducing property of DABM and provide further evidence for the potential value of this natural biomaterial for use in osseous reconstruction.
The effect of gamma irradiation on the enzymatic degradation of polyglycolic acid absorbable sutures
Authors: Chu C. C. , Williams David F. 
Published: May 2005

AbstractThe purpose of the study was to examine the effect of γ irradiation on the enzymatic as well as the in vivo degradation of polyglycolic acid sutures. The sutures of size 2–0 were irradiated at dosage levels of 0–20 mrad. The three enzymes chosen for this study, were esterase, α‐chymotrypsin, and trypsin. The irradiated sutures were both immersed in the enzyme solutions, their corresponding buffer controls, and implanted in inbred black‐and‐white hooded hister rats (Liverpool strain). The degradation of PGA sutures was determined mechanically. Among the three enzymes studied, esterase showed the highest enzymatic effect on the degradation of the unirradiated and irradiated PGA sutures. Trypsin's effect on PGA sutures was not observed until 20 mrad. The findings of trypsin demonstrated the hypothesis that synthetic high molecular weight polymers, which are initially resistant to enzymatic degradation, could become prone to enzymatic attack after altering their physical and chemical structures. Implanted PGA sutures maintained a similar or slightly higher mean tensile breaking strength in in vivo degradation compared to in vitro degradation (0.1M tris buffer of pH = 7.5); these degradation profiles suggest that PGA does not display similar behavior in in vivo and in vitro degradations. The magnitude of dissimilarity depends on the radiation dosage and on the duration of degradation, and is speculated to be attributable to the specific action of enzymes with respect to the con‐figuration and chemical structure of the PGA sutures.
Strain‐rate dependence of the compressive properties of normal and carbon‐fiber‐reinforced bone cement
Authors: Saha Subrata , Pal Subrata 
Published: May 2005

AbstractNormal and carbon‐fiber‐reinforced (1 wt. %) bone cement samples were tested in compression at various strain rates. Both the compressive strength and proportional limit increased in general with increasing strain rate. Similar strain‐rate sensitivity was also shown by the carbon‐fiber‐reinforced bone cement. The mechanical properties, namely the modulus of elasticity, the proportional limit, and the compressive strength of the carbon‐fiber‐reinforced bone cement showed highly significant positive correlations with the strain rate.
Variations between Biomer™ lots. I. Significant differences in the surface chemistry of two lots of a commercial poly(ether urethane)
Authors: Tyler B. J. , Ratner B. D. , Castner D. G. , Briggs D. 
Published: May 2005

AbstractWe have studied the surface chemistry of two lots of Biomer™ (BSP067 and BSUAOOl), and widely used commercial poly(ether urethane) (PEU). Although transmission infrared adsorption studies revealed no differences in the bulk chemistry of the two lots, the surface chemistry, as seen by x‐ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS), was different. Lot BSP067 showed softsegment enrichment at the surface, which is typical of PEU. Lot BSUAOOl showed no evidence of either hard‐ or soft‐segment PEU components at the surface. The surface of this lot was completely covered with a nonextractable additive identified as poly(diisopropy1 amino ethyl methacrylate). Small amounts of a low‐molecular‐weight antioxidant were observed at the surface of both samples. Because the biological response to polymers is dependent on surface structure, these results are of considerable importance to biomaterials research.
Formation of focal contacts by osteoblasts cultured on orthopedic biomaterials
Authors: Puleo D. A. , Bizios R. 
Published: May 2005

AbstractThe nature of the contact sites formed during the adhesion of osteoblasts to orthopedic implant materials was investigated by fluorescence microscopy. More specifically, the cytoskeletal organization of and the focal contact formation by neonatal rat calvarial osteoblasts attaching to and spreading on 316L stainless steel, Ti‐6A1– 4V, Co–Cr–Mo, Synamel (hydroxyapatite), alumina, and borosilicate glass were examined. Focal contacts are regions where the plasma membrane approaches the substrate to within 10–15 nm and where bundles of cytoskeletal microfilaments terminate. Fluorescent‐labeling of F–actin– containing microfilaments demonstrated a typical sequence of events as rounded, suspended osteoblasts spread onto the substrates. Immunofluorescent‐labeling of the protein vinculin, which is found at the cytoplasmic face of focal contacts, initially showed the formation of streak‐like focal patches. On the biomaterials, the vinculin staining subsequently extended up and along, but ventral to, the microfilament bundles. The fibrillar patterns observed at later times may evidence the formation of extracellular matrix contacts.
Synthesis of photoreactive poly(ethylene glycol) and its application to the prevention of surface‐induced platelet activation
Authors: Tseng Y.‐C. , Park K. 
Published: May 2005

AbstractPhotoreactive poly(ethy1ene glycol) (PEG) was synthesized by reacting 4‐fluoro‐ 3‐nitrophenyl azide (FNPA) with sodium salt of PEG. The synthesized 4‐azido‐2‐ nitrophenyl PEG (ANP‐PEG) was charac‐ terized by 1H‐NMR, IR, and UV spectro‐ scopy. ANP‐PEG was grafted to dimethyldichlorosilane‐coated glass (DDS‐glass) by photolysis without any premodification of the surface. The effects of various grafting factors, such as the polymer adsorption time, concentration of ANP‐PEG, and UV irradiation time, on the PEG grafting efficiency were examined. The PEG‐grafted DDS‐glass was characterized by measuring surface free energies, surface‐induced platelet activation, and the relative amount of PEG grafted on the surface using electron spectroscopy for chemical analysis (ESCA). Platelet adhesion and activation was analyzed by measuring the number and spread area of adherent platelets. The results showed that ANP‐PEG had to be adsorbed onto DDS‐glass for at least 12 h before photolysis for the maximum grafting efficiency. No platelets could adhere to the PEG‐grafted DDS‐glass, if the bulk concentration of ANP‐PEG in the adsorption solution was between 1 mg/mL and 10 mg/mL. Above 10 mg/mL, platelet activation gradually increased and reached the maximum at 30 mg/mL. Our data indicate that the grafting of ANP‐PEG requires careful control of the grafting conditions and that the grafted PEG can prevent surface‐induced platelet activation.
Cell adhesion and growth on synthetic elastomeric matrices containing ARG‐GLY–ASP–SER–3
Authors: Nicol Alastair , Channe Gowda D. , Urry Dan W. 
Published: May 2005

AbstractSynthetic elastomeric polypeptide matrices based on the repeating amino acid sequences of elastin have biophysical and biological properties which are favorable for prosthetic materials. An important requirement envisaged for some applications is the ability to support cell adhesion and growth. The X20–poly– (GVGVP), the γ–irradiation cross‐linked elastomeric matrix based on the repeatin poly[n(GVGVP), (GRGDSP)] containing the covalently incorporated cell adhesion sequence Arg–Gly–Asp–Ser (RGDS) were synthesized. These matrices were tested for their ability to support the adhesion and growth of bovine aortic endothelial cells and of bovine ligamentum nuchae fibroblasts. Adhesion experiments carried pentamer Val–Pro–Gly–Val–Gly, and X2 B – out in albumin‐containing media showed that matrices containing 60:1, 40:1, and 20:l ratios of (GVGVP):(GRGDSP) supported maximal cell attachment, that matrices containing 100:l exhibited an intermediate level of attachment and that matrices composed of 500:l and (GVGVP) alone were very poor supports for cell attachment. Serum in the media promoted submaximal cell attachment to X20–poly– (GVGVP) but did not permit substantial cell growth. Cell growth was supported by matrices having high ratios of (GRGDSP). Ratios of 60:1, 40:1, and 2O:l supported three population doublings of endothelial cells over 3 days resulting in confluent matrix‐adherent monolayers. Ratios of 40:l and 20:l similarly supported the growth of fibroblasts.