bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of rapid changes at plasma–solid interfaces
Authors: Vroman Leo , Adams Ann L. 
Published: December 2004

AbstractRecording ellipsometers and surface film balance, breath patterns, and ferric oxide powder “staining” were used to observe adsorption of normal plasma constituents onto metal oxide, silicon oxide, and polymer surfaces. Adsorbed proteins could be identified by their ability to adsorb matter from corresponding antihuman sera. Data indicate that oxidized silicon crystal surfaces adsorbed fibrinogen out of plasmas within 2 sec; within 20 sec, these films lost their ability to attract antifibrinogen and were later partially removed if intact factor XII was present in the solution. One aminated nonheparinized polymer formed films that adsorbed large amounts of fibrinogen and some gamma globulins out of plasma in the ellipsometer, and platelets out of platelet‐rich plasma, as well as ferric oxide out of aqueous suspension. After taking up heparin, these polymer films appeared able to adsorb only small amounts of protein or oxide, and no detectable amounts of fibrinogen or platelets. On another aminated polymer, heparin seemed without effect. Interaction of metal surfaces with plasma may be complicated by oxidation.
Thermodynamics of adsorbed protein films
Authors: Levine Sumner N. 
Published: December 2004

AbstractPrevious investigation implicated surface charge and surface energy as factors which affect blood clotting. The present paper attempts to explore the theoretical basis for these affects. Expressions are also derived relating change and interfacial tension to the binding constants of the protein. Finally, the possibility of phase transition of the adsorbed protein is discussed and techniques for detecting such changes from adsorption measurements are presented.
The role of heparin in intrinsic blood coagulation
Authors: Pitlick Frances A. , Lundblad Roger L. , Davie Earl W. 
Published: December 2004

AbstractA number of inhibitors of intrinsic blood coagulation have been examined. Particular emphasis was placed on heparin, heparin analogues, and hirudin. These inhibitors interfere primarily with two clotting factors in the intrinsic clotting scheme. These include factor IXa and thrombin. Our data suggest that factor IXa is the heparin‐and hirudin‐sensitive factor in plasma when coagulation is initiated via factors XII or XI, and that subsequent clotting factors remain in inactive forms. Studies with heparin and hirudin also clarified the role of thrombin in the interaction of factors IXa and VIII. It was concluded from these experiments that factor VIII readily interacts with factor IXa in the presence of calcium ions and phospholipid independent of thrombin.
Effects of proteins on elution of heparin from anticoagulant surfaces
Authors: Usdin Vera R. , Fourt Lyman 
Published: December 2004

AbstractExposure of heparin‐bearing anticoagulant materials to whole blood, plasma, or serum has been shown to lead to partial elution of heparin. Similar effects are obtained when graphite–benzalkonium–heparin (GBH) or poly–4–vinyl–pyridine–heparin (PVPyrH) surfaces are exposed to bovine plasma protein fractions. Loss of heparin from these anticoagulant materials appears to be dependent on the nature of the cationic surface and on the particular protein fraction used. With whole blood and plasma, and with most of the protein fractions studied, it was found that a larger fraction of the original heparin was eluted from GBH than from PVPyrH. Surfaces exposed to bovine Cohn fraction IV lost considerably more heparin than similar surfaces exposed to Cohn fractions I, II, III, or V, and fraction V removed less than the others, at the same or higher concentrations, and less from PVPyrH than from GBH.
Thrombin adsorption and possible relations to thrombus formation
Authors: Waugh David F. , Baughman D. Joe 
Published: December 2004

AbstractIn the circulation, adherent thrombi are most likely formed by nucleation and growth processes. The adsorption of an anchoring layer must be followed by further constituent interactions; these by crosslinking introduce cooperative effects which affect nucleation and growth rates. Adsorption of thrombin to nonpolar surfaces has been examined using a clotting time assay. Assay discrimination was determined by coefficients of variation: of the assay itself (0.6%), of reproducing diluted thrombin sources (0.37%) and of reproducing sets of dotting tubes containing fibrinogen (1.5%). Adsorptions are 0.54 mg/m2 at the solution–air interface, 0.77 mg/m2 at the solution–clean wall interface, and 0.04 mg/m2 to walls previously treated with thrombin. Average distance between thrombin molecules is 89 Å, the minimum adsorption energy is −11.7 kcal/mole and estimated thrombus adhesive strength 10kg/cm2. Thrombin can be the anchoring layer for a thrombus which contains thrombin, fibrin and platelets since all constituents interact with each other. The thrombin–fibrin intersection energy is about −7 kcal/mole. The platelet can, at least on interaction with thrombin, undergo structural changes which increase interaction. A variety of interactions and cooperative effects are possible. A problem is to develop protocols and assays which will permit specification of the anchoring layer and characteristics of subsequent interactions.
Specfific coagulation factor adsorption as related to functional groups on surfaces
Authors: Oja P. D. , Holmes G. W. , Perkins H. A. , Love J. 
Published: December 2004

AbstractFactor assays of normal citrated plasma following incubation with nonleaching heparinized surfaces in high surface area–plasma volume ratios showed a marked pattern of reduction in factor IX activity, with lesser depression of II and X. No or modest effect on other factors was observed. In particular, no significant adsorption of factor XII (Hageman) by either cationic or anionic surfaces, was found. No consistent pattern of effects was seen with a group of strongly anionic surfaces, analogous to the sulfate and sulfamate groupings of the heparin molecule. However, certain members of this class showed profound effects on factor XI.
Initial events in interactions of blood with a foreign surface
Authors: Baier Robert E. , Dutton Robert C. 
Published: December 2004

AbstractThe nature of the events occurring immediately after exposing foreign surfaces to fresh flowing blood was assessed using a combination of MAIR infrared spectroscopy, ellipsometry, and contact angle measurements. Within the first 5 sec after contact with blood issuing from the jugular veins of lightly anesthesized dogs, germanium prisms were uniformly coated with strongly adherent proteinaceous filsm having an average optical thickness equivalent to 2 layers of stearic acid (approx. 50 Å) and having critical surface tensions of about 36 dyne/cm. A contact time of 60 sec led to a less uniform coating of average optical thickness equivalent to 5 layers of stearic acid (approx. 125 A), but with similar MAIR spectrum and wettability. The internal refelection spectra were consistent with the presence of either alpha‐helical or random‐chain configurations, but not with the extended chain beta‐structure for proteins. Films cast from purified fibrinogen on platinum foils gave similar spectra and exhibited similar wetting properties; these observations are consistent with the hypotehsis that initial adsorptive events are dominated by fibrinogen deposition. The involvement of small amounts of lipid or other protein remains a distinct possibility, however.
Biochemical engineering materials screening and monitoring
Authors: Homsy C. A. , Hodge R. , Gordon N. , Braggs E. E. , Estrella M. 
Published: December 2004

AbstractThis work was motivated by the need for a systematic compatibility screen for materials of interest for heart assist devices. A practical polymer screening and monitoring program for biochemical engineering materials was developed. Initial emphasis was placed on screening to measure degradation to low molecular weight, water miscible moieties over simulated in vivo exposure. Infrared spectrographic analysis of the simulated body fluid showed that the level of organic moiety corresponds to general clinical experience. Further confirmation of the technique came from evaluation of control polymers from The University of Texas Drug Research Laboratory. Correlation of results with cell culture viability in the presence of the pseudo body fluid is being carried out.
Retention of Freon in poly(n‐butyl α‐cyanoacrylate) sprayed films
Authors: Leonard Fred , Lusardi Joseph J. , Kulkarni Ramchandra K. , Wade Clarence W. R. 
Published: December 2004

AbstractIt has been found that when n‐butyl α‐cyanoacrylate is sprayed on a blood surface from an aerosol containing Freon as the propellant, the polymeric cyanoacrylate film which forms contains 1.4% propellant under the spray conditions used. Studies of the rate of loss of propellant from the film indicate that ⅓ of the Freon initially present in the film still remains after 90 min of exposure of the film to air. Possible implications of these results are discussed.
Reevaluation of plastic tubings currently used in medical and paramedical applications
Authors: Lawrence W. H. , Turner J. E. , Autian J. 
Published: December 2004

AbstractA tissue culture test and a 7 day implantation method in rabbits were used to screen the toxic potential of 50 tubings used in one or more medical or paramedical applications. Results of the tests revealed that approximately 32% of the tubings contained one or more ingredients which, when released to cells or tissue, caused a toxic response. A similar study six years previously showed that 52% of the tubings tested had toxic potential. It is apparent that improvements have been made in the medical tubings (from point of view of safety), but steps must still be taken to reduce the potential risk to levels approaching zero.
Surgical suture materials coated with a layer of hydrophilic Hydron gel
Authors: Tollar M. , Štol M. , Kliment K. 
Published: December 2004

AbstractSurgical suture materials were coated with a layer of hydrophilic Hydron gel. By tests carried out on tissue cultures, it has been verified that this layer itself improves the tolerance of the fiber by the organism. In addition, appropriate biologically active substances (e.g., antibiotics), preventing either the development or spreading of an infection along the fiber, may be incorporated into the gel layer. Neither the knotting ability nor other mechanical properties of the fiber are influenced by the gel coating. Preliminary clinical experiments showed good results.
Artificial membranes for corneal surgery
Authors: Refojo Miguel F. 
Published: December 2004

AbstractThe most commonly used synthetic polymers in corneal implants are reviewed from the viewpoint of their properties and tissue tolerance. Special attention is given to the properties of these materials in in regard to their application as artificial corneal epithelium and endothelium. It is postulated that an ideal artificial corneal membrane must exhibit, as closely as possible, the physical properties and the functional characteristics of the natural membrane. Of all the known artificial materials, homogeneous hydrogels seem to offer the best possibilities as membranes for corneal surgery. Three types of hydrogels were investigated. Poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(glyceryl methacrylate) (PGMA) are covalently linked tridimensional nonionic networks. The third type of hydrogel has multiple ionic crosslinks and belongs to the family of the polyelectrolyte complex hydrogels, made by reacting poly(vinylbenzyl‐trimethylammonium chloride) with sodium poly(styrenesulfonate). The acrylic hydrogels are very well tolerated by living tissues, but the polyelectrolyte complexes gave inconsistent results. Membranes of either type were made having permeability to water similar to that of the corneal layers. Most hydrogels are friable and do not hold sutures; this difficulty was solved by attaching the hydrogels are friable and do not hold sutures; this difficulty was solved by attaching the hydrogel membrane to the cornea by means of alkyl cyanoacrylate adhesives. n‐Heptyl and n‐butyl 2‐cyanoacrylate gave very good results in this application.
Invited communication. Adhesion between living tissue and plastics. I. Adhesion of epoxy and polyurethane resins to dentin and enamel
Authors: Lee Henry L. 
Published: December 2004

AbstractIn previous papers,3,4 we have discussed the synthesis of epoxy resins suitable for dental and orthopedic adhesives. In this paper we have outlined our research on two other critical aspects: surface preparation and test methods.
Tensile strength determination of the interface between porcelain fused to gold
Authors: Kelly Mike , Asgar Kamal , O'Brien William J. 
Published: December 2004

AbstractA method of testing the tensile strength of the porcelain–gold bond has been developed. Tensile strengths of the bond are improved primarily by the formation of an oxide layer on the gold before baking the porcelain and not by the degree of gross surface roughness. The oxide layer may act either as a transition ayer or it may create microsurface roughness. The gross surface roughness probably complicates the wetting action of the porcelain on the gold. Whether the actual bond is of a chemical nature, physical nature, or both, remains uncertain.
Effect of casting conditions on physical properties of some experimenal partial denture alloys
Authors: Asgar Kamal , Techow Bruce , Allan F. C. , Sutfin L. V. 
Published: December 2004

AbstractFour alloys were tested which are being considered for use in making partial denture castings. The procedure was varied by using three spruing methods, two different waxes, two melt temperatures, and two different directions of filling. Statistical analysis techniques were used to determine the significance of the results. Spruing method was the most highly influencial of the variables and the flat method gave the best results. This method also is most relevant to clinical procedure. The effect of temperature, in fewer instances, was also in fluential. At a lesser level of signifiacnce direction of filling, and in one instance wax, had an effect.
Thromboresistant polymers by emulsion polymerization with anionic surfactants. I
Authors: Leonard Fred , Nielson Carl A. , Fadali A. Moniem , Gott Vincent L. 
Published: December 2004

AbstractAn elastomeric terpolymer of butyl acrylate, methyl methacrylate and methacrylamide was synthesized by emulsion polymerization using an anionic sufactant. The latex terpolymer particles where shown to have a negative charge and the solid terpolymer was negatively charged with respect to Ringer's solution. Caval rings prepared from the latex and properly post treated and cured remained patent after implantation in the inferior vena cava of dogs through a 2 week period, thus demonstrating significant thromboresistance.
Electrochemical studies on the adsorption of amino acids in relation to the compatibility of prosthetic materials and the human body
Authors: Matthews Dennis B. 
Published: December 2004

AbstractThe Lippman electrocapillary method was used to survey the adsorption behavior of 25 amino acids at the mercury‐solution interface. The amount of surface excess of adsorbed amino acid (Γ;), as evidenced by lowering of interfacial tension, was found to increase with the number of double bonds and/or additional nitrogen atoms which provide electron pairs. No influence of dipole moment on adsorption was observed. Adsorption was more extensive at potentials positive to the potential of zero charge, indicating a possible electrontransfer adsorption mechanism, i.e., a sharing π‐electrons rather than dipole interaction with the metal. These results are consistant with the enhanced adsorption of proteins at anodic potentials since the side groups extending from peptide linkages on a given protein are the R groups of various amino acids.
Screening study of adsorbents for urea removal from artifical kidney dialyzing fluid
Authors: Mehall J. R. , Koenig J. L. , Lindan O. , Sparks R. E. 
Published: December 2004

AbstractA large number of activated carbons, carbon blacks, ion exchange resins, and inorganic adsorbents were screened for their capacity to remove urea from dilute neutral solution. An adsorbent capable of performing this task would be of assistance in decreasing the volume of dialyzing fluid required for hemodialysis. All activated carbons and carbon blacks had some adsorption capacity for urea. The most efficient was a carbonized poly(vinylidene chloride). The inorganic adsorbents exhibited negligible urea adsorption capacity, as did ion exchange resins in the ionic form at equilibrium with simulated dialyzing fluid. Several chemical reactions for urea were found not to procede in dilute neutral solution, even with carbon present to adsorb reaction products. Attenuated total reflectance infrared spectroscopy showed no band shifts in urea adsorbed on strong acid ion exchange resin. Measurement of the spectrum of urea adsorbed on carbon was prevented by adsorption of the incident energy by the carbon.
Polymers as bearing materials for total hip replacement: A friction and wear analysis
Authors: Amstutz Harlan C. 
Published: December 2004

AbstractCertain thermoplastic polymers possess numerous desirable physical and mechanical properties important for total joint replacement. Their modulus of clasticity and density are close to the cartilage bone composite. Their elasticity would provide valuable damping for the transmission of shock forces. As a class of materials, polymers do not have the compression and tensile strength of metals, but the high strength‐to‐weight ratio of some polymers makes them especially attractive as a material for the socket half of the joint. The socket shape could be easily molded or machined and at a low cost. As a prime requisite they must have sufficient wear and creep resistance for a lifetime of cyclic loading and sliding. In addition they must be biologically tolerated, and the joint environment must not degrade or otherwise adversely affect the physical and mechanical properties of the polymer.The purpose of this paper is to present a friction and wear analysis of ten thermoplastic polymers selected because their individual physical and mechanical properties suggested good wear and creep resistance. Polyimides with and without graphite have particular potential as a bearing material. The toxicological aspects of these materials are under study and will be the subject of a subsequent report.
Membrane resistance of semipermeable microcapsules
Authors: Jay Alfred W. L. , Sivertz Kristin S. 
Published: December 2004

AbstractThe electrical resistance of semipermeable nylon membranes on hemoglobin microcapsules has been measured by means of microelectrode punctures.The thickness of the nylon membranes has been shown to be constant and independent of microcapsule diameter. The specific resistivity of the membrane has been estimated to be 5.6 × 103 ohm‐cm2.
Disassociation of conjugated proteins in the presence of porous glass
Authors: Stinson Harold R. 
Published: December 2004

AbstractThe disassociation of hemoglobin in saline solution in the presence of high surface area, powdered, porous glasss was determined. A porphyrin‐protein conjugate was disassociated at the porphyrin‐protein bond. No hydrolysis was observed at the peptide bond.
Enzymatic and electrochemical polymerization of fibrinogen
Authors: Stoner Glenn , Walker Louise 
Published: December 2004

AbstractAnodic electrolysis of fibrinogen at platinum electrodes causes the formation of fibrin‐type structure at potentials below .08 V S.C.E.; at higher potentials denaturation occurs. Coated electron microscope grids were used as electrodes in fibrinogen solutions. When removed and dried these grids contain a protein film which acts as a sampler‐substrate for entities which are either in solution or are formed at the electrodes.
Electrosorption of amino acids peptides and proteins in relation to the compatibility of materials and the human body
Authors: Stoner Glenn E. 
Published: December 2004

AbstractThe adsorption behavior of several amino acids, simple peptides and the protein fibrinogin was measured at a charged mercury surface. Evidence was obtained for the significance of π‐electron containing amino acid groups in the adsorption of proteins on surfaces. Experiments on fibrinogin indicate that electrochemical polymerization of that protein may be the cause of thrombosis at anodes.
Identification of adsorbed protein films by exposure to antisera and water vapor
Authors: Vroman L. , Adams Ann L. 
Published: December 2004

AbstractDrops of various antisera against human proteins were placed onto hydrophilic or hydrophobic surfaces that had adsorbed human proteins. The rinsed and dried plates were exposed to water vapor. Wherever an antiserum droplet had resided on a matching protein film, vapor scattered least light, indicating greatest wetting. The protein deposited within 5 seconds by plasma onto glass proved to be fibrinogen.
The effect of n‐butyl 2‐cyanoacrylate on liver function
Authors: Houston Stuart , Ousterhout Douglas K. , Sleeman Kenneth H. , Leonard Fred 
Published: December 2004

Abstractn‐Butyl 2‐cyanoacrylate was implanted subcutaneously in dogs and eight different liver function tests were employed over a 6‐month period in order to determine the effect of the cyanoacrylate on liver function. The biochemical results indicated that all the values obtained were within the normal range of values reported for the dog. Pathological studies on all vital organs showed that the subcutaneously implanted cyanoacrylate polymer did not appear to cause harmful effects on the vital organs.
Polarization studies of surgical materials in ringer's solution
Authors: Mueller H. J. , Greener E. H. 
Published: December 2004

AbstractThe corrosion resistance of materials employed for surgical applications was dertermined and compared by means of potentiostatic anodic polarization techniques. In a physiological saline solution the passive breakdown potential of stainless steel materials was dependent upon the oxygen content opf the solution, and the microstructure of the material. The breakdown is passivity was found to be due to a pitting type of corrosion attack. Pure titanium remained passive within the limits employed in this investigation. Even though cast vitallium did not exhibit passivity breakdown in the form of a pitting attack, polarization behavior between the behavior for stainless stell and pure titanium was observed.
Tensile and compression properties of hydrophilic composite materials on a simple model of cartilage. II
Authors: Flam E. , Kapfer W. H. , Brenner W. , Schubert M. 
Published: December 2004

AbstractComposite hydrophilic materials (CHM) containing collagen or cellulose as the insoluble fibrous component and potassium salts of proteinpolysaccharide or carboxymethylcellulose as the soluble polyelectrolyte were prepared as simple models of the connective tissue, cartilage. The tensile properties of uncrosslinked and formaldehyde‐crosslinked collagenous CHM were measured and compared to those of bovine nasal cartilage (BNC). The compressive properties of uncrosslinked and formaldehyde‐crosslinked cellulosic CHM were measured and compared to bovine nasal cartilage. Although elongating to approximately the same extent before breaking (20%), the uncrosslinked collagenous CHM had lower tensile strengths than BNC (330 psi). Formaldehyde crosslinking increased the tensile strength of the collagenous CHM to as much as 3 times that of BNC but reduced the elongation at failure to only 7%. The uncrosslinked cellulosic CHM attained a maximum of only ¼ the compressive strength of BNC (940 psi). Formaldehyde crosslinking extended the compressive strength to as high as ⅓ that of BNC. The results indicate that the simple uncrosslinked and crosslinked models can only partially account for the mechanical properties of BNC.