bluuebunny/crossref_metadata_2025 huggingface dataset:
Endosomal fractions from viral K‐ras‐transformed MDCK cells reveal transformation specific changes on two‐dimensional gel maps
Authors: Huber Lukas A. , Pasquali Christian , Gagescu Raluca , Zuk Anna , Gruenberg Jean , Matlin Karl S.
Published: May 2005

We have investigated the effects of viral Kirstenrasoncogene expression in Madin‐Darby canine kidney (MDCK) II epithelial cell on the differential protein expression of organelle proteins. MDCK cells, stably transformedviainfection with a helper‐independent retroviral vector construct, were grown on permeable filter supports. Whereas normal cells form highly polarized monolayers,ras‐transformed cells display an unpolarized phenotype, detaching from the substratum and developing multilayers (Schoenenberger, C.‐A.et al.,J. Cell Biol.1991,112, 873–889). We postulate that this breakdown of epithelial polarity reflects disturbed intracellular protein transport and sorting, namely, proteins will no longer be sorted correctly in intracellular organelles and will therefore not reach their appropriate target membrane. Here we emphasize the role of endosomes as sorting platform in epithelial cells. We found significant differences in the molecular composition of endosomes from normalvs.oncogenic transformed epithelial cells, strengthening previous evidence indicating that oncogenic transformation results in abnormal expression of normal genes (Celis, J. E., Olsen, E.,Electrophoresis1994,15, 309–344) as well as the expression of new ones (Huber, L. A.et al.,Electrophoresis1994,15, 468–473).
Use of capillary electrophoresis methods to characterize the pharmacokinetics of antisense drugs
Authors: Chen Shu‐Hui , Gallo James M.
Published: May 2005

As antisense drugs become mature for clinical trials, analytical techniques to analyze antisense DNA in biological media for characterization of their pharmacokinetics will be in demand. Due to the superior resolving power of capillary gel electrophoresis (CGE), CGE will likely be a preferred method in quantifying intact oligonucleotides as well as the putative metabolic products. Nonetheless, biological mediums can influence the stability of the gel column, making a CGE assay time‐consuming. In one approach, high‐performance liquid chromatography (HPLC) was used to quantify the total amount of antisense compounds to increase the sample throughput and CGE was used to determine the relative percentage of the intact and metabolic species on specific samples. Alternatively, extensive sample pretreatment procedures were performed and the samples were quantified and characterized directly by CGE alone with the use of an internal standard. Both methods have been used to characterize the pharmacokinetics of antisense compounds. This review focuses on the instrumental and technical aspects of analyzing antisense DNA in biological mediums using CGE either as a single or a combined method towards better understanding of the pharmacokinetics of antisense DNA. Moreover, the newer analytical technologies of capillary electrophoresis (CE), which hold great potential to be used for pharmacokinetic applications, such as the replenishable sieving matrix combined with an innovative coupling approach and microchip CE, will also be explored.
Analysis of cefadroxil by micellar electrokinetic capillary chromatography: Development and validation
Authors: Li Yong‐Min , Vanderghinste Dominique , Pecanac Darka , Schepdael Ann Van , Roets Eugène , Hoogmartens Jos
Published: May 2005

A method is developed and validated for analysis of the antibiotic cefadroxil using micellar electrokinetic capillary chromatography. It permits cefadroxil to be completely separated from ten of its known related substances within 15 min (including the washing procedure). The separation is performed in an acetate buffer (50 mM, pH 5.25) containing sodium dodecyl sulfate (SDS; 110 mM). The fused‐silica capillary was 44 cm long (36 cm effective length), 50 μm ID; the voltage, 18 kV; temperature, 15°C; and the detection wavelength; 254 nm. The influence of the type of buffer, buffer pH and concentration, and of the SDS concentration was investigated. The robustness of the method was examined by means of a full‐fraction factorial design. The parameters for validation such as linearity, precision, limit of detection and limit of quantitation are also reported.
Analysis of vitamin formulations by electrokinetic chromatography utilizing tetradecylammonium ions as the pseudostationary phase
Authors: Næss Øystein , Tilander Tuija , Pedersen‐Bjergaard Stig , Rasmussen Knut Einar
Published: May 2005

A recently proposed method for the separation of fat‐soluble vitamins by electrokinetic chromatography was further developed and investigated in the present study. The separation medium consisted of acetonitrile‐water (80:20 v/v) and contained 80 mM tetradecylammonium bromide (TDA+); the content of acetonitrile served to maintain the hydrophobic vitamins dissolved during electrophoresis, while the TDA+ ions served as the pseudostationary phase. With the cathode placed at the outlet of the capillary, the fat‐soluble vitamins were separated based on different hydrophobic interactions to the TDA+ ions and migrated in order of decreasing hydrophobicity prior to the electroosmotic flow. Migration time stability was significantly enhanced by the addition of 4 mM borate to the separation medium. The separation system was validated for the determination of vitamin E acetate in commercial tablets; quantitative results deviated by less than 3.5% from specified values, varying by less than 2.5% relative standard deviation (RSD) for within‐day experiments, and by less than 6.5% RSD during between‐day experiments. The separation system was compatible with injection solvents ranging in polarity from water to tetrahydrofuran, and was even capable of separating the water‐soluble vitamins B1, B2, B12, and nicotinamide.
Determination of bupivacaine and three of its metabolites in rat urine by capillary electrophoresis
Authors: Schieferecke Mark A. , McLaughlin Kieran J. , Faibushevich Alexander A. , Lunte Craig E.
Published: May 2005

A capillary electrophoretic (CE) method for the analysis of urinary extracts of the local anesthetic, bupivacaine, and its three main metabolites, desbutylbupivacaine, 3′‐hydroxybupivacaine, and 4′‐hydroxybupivacaine, in rat urine has been developed. The limits of detection were 0.22 μM for desbutylbupivacaine and bupivacaine, 0.15 μM for 3′‐hydroxybupivacaine, and 0.16 μM for 4′‐hydroxybupivacaine. The linear range was from 0.7 μM to 16.8 μM for all four compounds. Migration time and peak height reproducibilities, and extraction efficiencies were determined for all four compounds. Peak height reproducibilities (n = 5) for the overall method were improved through the use of prilocaine as an internal standard. Peak height reproducibilities were 5.6% RSD for desbutylbupivacaine and bupivacaine, and 9.9% RSD for 3′‐hydroxybupivacaine and 4′‐hydroxybupivacaine. Migration time reproducibilities (n = 5) were 2.4% for all compounds. Urine samples were collected from rats administered therapeutic doses of bupivacaine and extracted using a solid‐phase extraction method (SPE). Separation of bupivacaine and its metabolites was achieved in 15 min.
Determination of atropine in biological fluids by micellar electrokinetic capillary chromatography in the presence of strychnine and tetracaine
Authors: Plaut Olivier , Staub Christian
Published: May 2005

The identification and quantitation of atropine, in whole blood and gastric contents in the presence of strychnine and tetracaine is described. This method uses liquid‐liquid extraction and micellar electrokinetic chromatography (MECC). Separations are made using a 50 cm long capillary and a borate/phosphate buffer at pH 9.2 with 50 mM sodium dodecyl sulfate (SDS). Linearity was established for the three compounds between 1.0 and 100 μ/mL, using scopolamine as internal standard. The limit of detection for atropine was estimated at 0.06 μ/mL and the limit of quantitation at 0.2 μg/mL. The run time is less than 30 min. Alternate parameters are proposed to reduce the run time to under 10 min. The method was applied to a forensic post‐mortem case.
Determination of titanocene, a new drug with anticancer potential, and its metabolism in solution by capillary electrophoresis
Authors: Wittrisch Holm , Schröer Hans‐Peter , Vogt Jürgen , Vogt Carla
Published: May 2005

Titanocene dichloride is one of the most promising cancerostatica of the future: nevertheless, its high activity against several tumor cells was discovered 20 years ago. Detailed knowledge of the mechanism of hydrolysis of titanocene dichloride and its stability in the infusion liquid is a prerequisite for clinical tests and for a successful application for permission as medication. Capillary electrophoresis (CE) was used to observe the hydrolysis behavior of titanocene dichloride in aqueous solutions. The hydrolysis products were separated in a 20 mM phosphate buffer, pH 6, and in a 20 mM malic acid buffer, pH 3. Up to five hydrolysis products were obtained. A significant influence of the sample preparation (pH, isoionic additives) on the hydrolysis rate was observed. The hydrolysis products were characterized by the UV scan and the element‐selective particle‐induced X‐ray emission (PIXE) detection technique. The results obtained correspond with the hydrolysis mechanism described in the literature. The determination of free titanocene dichloride in human plasma failed due to the high affinity of the plasma proteins for this compound.
Charged chelate—capillary electrophoresis of endogenous corticosteroids
Authors: Palmer James , Atkinson Shannon , Yoshida Wesley Y. , Stalcup Apryll M. , Landers James P.
Published: May 2005

Separation of endogenous 17‐ or 18‐hydroxylated corticosteroids (of the 21‐hydroxylated 4‐pregnen series) as charged chelates in capillary electrophoresis with borate as the ligand is demonstrated. Aldosterone, 18‐hydroxycorticosterone, 18‐hydroxy‐11‐deoxycorticosterone, cortisone, cortisol, and 11‐deoxycortisol are separated and resolved by 400 mM borate buffer at pH 9.0. Separation characteristics of the corticosteroid charged chelates were examined by varying the separation buffer borate concentration, pH, ionic strength, and addition of organic modifiers. The borate ion [B(OH)4]− is identified as the critical buffer component. Corticosteroids chelate borate with proximal hydroxyls composed of either the 17‐ or 18‐hydroxyl in combination with the 21‐position hydroxyl. Corticosteroid/borate chelation as indicated by CE results is corroborated with 11B‐nuclear magnetic resonance (11B‐NMR) sprectra. Chelation is a readily reversible process, with the strength of the resultant chelate, as opposed to the charge‐to‐mass ratio, predominantly determining analyte mobility in charged chelate ‐ capillary electrophoresis (CC‐CE).
Smoke dilution methods for the evaluation of the smoke emission from burning polymers: A comparative approach
Authors: Ballistreri Alberto , Montaudo Giorgio , Puglisi Concetto , Seamporrino Emilio , Vitalini Daniele
Published: May 2005

A comparative approach to the determination of smoke emission from burning polymers has been attempted, and a number of combustion conditions and detection devices have been tried to choose a test method for measuring the smoke proiduction of materials. The combustion apparatus adopted is a hot‐air quartz furnace that permits the measured by dynamic method from combustion of PAN, PVC and PVC mixed with some metal oxiders, have been compared with those obtained by an accumulation mode. For PVC the intensity of the light scattered from the evolving smoke has been measured as an alternative to smoke density.
The effect of sample size on the burning behaviour of thermoplastic materials in the critical oxygen index test
Authors: Wharton R. K.
Published: May 2005

The dependence of the Critical Oxygen Index values of some thermoplastic materials on sample sixe is reported. The extent of melting of this class of material is shown to be important in determining the effect of sample size on the index.
Customized neonatal incubator for measurement of platelet‐artificial microvascular graft interactions under controlled flow, temperature, and transmural pressure
Authors: Johnson Peter C. , Sheppeck Richard A. , Berceli Scott A. , Borovetz Harvey S. , Bentz Michael L. , Garrett Kevin O. , Janosky Janine E.
Published: May 2005

A neonatal incubator has been custom modified to enable measurement of initial platelet retention on biomaterials in vitro under clinically relevant hemodynamic conditions. To calibrate this device, platelet retention on several materials having microconduit geometry (0.7–1.0 mm i.d.) has been measured after perfusion with citrated whole blood (containing 111 Indium‐labelled platelets) at a shear rate of 312 s−1, 37°C, and 80 cm H2O transmural pressure. The relative reactivity of these materials toward platelets was: glass < Fibrinogen(Fg)‐coatedglass < Fg‐coated polyethylene < polyethylene ∼ = Expanded polytetrafluoroethylene. Interindividual variation is relatively large (coefficient of variation = 35.5 ± 9.3%), but comparison to intraindividual controls reduces the variability to 14.8 ± 10.3%, a level which is suitable for economical testing of platelet retention to biomaterials in the presence or absence of drugs. This approach may have particular value in the study of the mechanism of platelet interactions with artificial microvascular grafts under perfusion conditions which are relevant to the first moments of flow, when initial platelet deposition occurs.
Vibrational response analysis: Non‐destructive evaluation of ingrowth into porous coated implants
Authors: George Thomas F. , Abrams Charlie F. , Richardson Daniel C. , Deyoung David J. , Carlson Cathy S. , Meutin Donald
Published: May 2005

Quantitative methods of evaluating ingrowth into porous coated implants have traditionally involved destructive mechanical testing. In this study, it was hypothesized that the response to a vibrational stimulus could estimate the shear strength at the bone‐implant interface as measured by pushout. A derived model predicts that the square of the frequency at resonance is linearly related to this interfacial strength. It was further hypothesized that the level of vibration required for a meaningful response would not be destructive. This study was done using nonloaded, porous coated cylindrical implants which were press fit in the distal femora of dogs. Femora were harvested at 2, 4, and 6 weeks postimplantation. The implants were sectioned into 4‐mm slices and then evaluated by vibration, pushout, and light microscopy. Vibrational response analysis was conducted with broad band random excitation using Fast Fourier transform signal analysis. Pushout values were obtained using a materials testing machine. The resulting correlation was statistically significant (F = 201, r2 = 0.90, p < 10−6). Light microscopic evaluation of vibrated samples showed no difference at the bone‐implant interface when compared to controls.
Does vacuum mixing of bone cement affect heat generation? Analysis of four cement brands
Authors: Wang Jian‐Sheng , Franzén Herbert , Toksvig‐Larsen Søren , Lidgren Lars
Published: May 2005

Four different brands of bone cement (Palacos R, Simplex P, Sulfix, CMW 1) were tested for exothermic changes during polymerization at atmospheric pressure and under partial vacuum of 0.2 bar. Palacos R was also mixed at four pressure levels (1.0, 0.2, 0.12, and 0.05 bar). The peak temperature in the bone cement was 46 to 124 °C, depending on the measuring point. There was no difference in peak temperature or duration of temperature increase above 50 °C during the curing of cement whether mixed at atmospheric pressure or under partial vacuum at different pressure levels. © 1995 John Wiley & Sons, Inc.
A new method for preparing nonthrombogenic plastic surfaces
Authors: Eriksson Jan Christer , Gillberg Gunilla , Lagergren Hans
Published: May 2005

The present paper describes a new technique for preparing the surface of polyethylene and polypropylene plastics for the adsorption of heparin. The procedure consists of exposing the plastic surface to a solution of cationic surfactants at a temperature close to the softening temperature of the plastic. The mechanism of adsorption of the anticoagulant of the surfaces is discussed.
Preliminary clinical trials of a new oral adhesive bandage
Authors: Scopp Irwin Walter , Heiser Ralph A.
Published: May 2005

A new intraoral adhesive bandage composed of gelatin, sodium carboxymethylcellulose, and polyisobutylene backed by a layer of polyethylene film was used by 148 investigators in 1468 patients. The bandage adhered well to the fixed mucosa of the palate, gingiva, and teeth. It adhered less satisfactorily to the loose mucosa of the cheek and floor of the mouth. It did not adhere very well to the tongue. The duration of adhesion of the bandage was at least 5 hr in approximately 87% of all treated cases, and it remained in place for 9–51 hr for more than 50% of all treated patients. Tolerance of the application was good or excellent in 75% of all cases. There was no irritation attributable to the bandage in any patient. The bandage provided an effective means of protecting the vital repair mechanism of a wound during the early hours after extraction. The results of these trials indicate that the new adhesive bandage is safe and that it provides effective cover and protection of wounds and lesions of the mucous surface up to 24 hr.
Tissue reaction after implantation and in situ polymerization of hydrophilic gel
Authors: Hubacek J. , Kliment K. , Dusek J. , Hubacek Jar
Published: May 2005

The authors followed the tissue response of a new plastic tube composed of neutral hydrophilic gel, after implantation in the subcutis of rats. They further studied tissue reaction when gel rods were connected by polymerization in situ. After implantation, the gel tubes developed a fine encapsulation but no inflammatory response. The gel rods were connected “end to end” by means of a drop of the polymerizing mixture. The healing proceeded in the same manner with the exception that minute granules of macrocellular elements were formed in the ligament surrounding the polymerization mixture remnats. According to these results, the neutral hydrophilic gel has proved to be a suitable material for implantation.
Corrosion rate measurements in vivo
Authors: Colangelo V. J. , Greene N. D. , Kettelkamp D. B. , Alexander H. , Campbell C. J.
Published: May 2005

Corrosion resistance is particularly important in medical treatments requiring implantation of metallic objects in the human body. Unfortunately, weight loss measurements and other conventional corrosion testing techniques are insufficiently sensitive and difficult to adapt to in vivo environments. The linear polarization technique can be used to remotely meaure the corrosion rates of metals implanted in tissue using needle probes. The principles of this technique are reviewed and the results of tests performed on steel, cobalt, and molybdenum implanted in experimental animals are discussed.
Phenols and blood coagulation
Authors: Nour‐Eldin F.
Published: May 2005

The effect of phenol and certain phenyl compounds on the different stages of the blood coagulation and fibrinolytic mechanism is investigated. Phenol has a complex action on blood coagulation. In an optimal concentration of 0.3% it produced a definite, though suboptimal platelet factor 3 activity, evolved factor XII, accelerated thrombin–fibrinogen interaction, retarded clot retraction, enhanced the action of streptokinase on plasminogen, and inhibited plasmin. In addition, in the absence of factor XIII and calcium, it increased the solubility of fibrin in urea. Phenyl acetaldehyde, benzyl benzoate, and styrene (phenyl ethylene) accelerated stypven clotting time and thrombin–fibrinogen reaction. Unpolymerized styrene and phenyl ethanol specifically inhibited the action of plasma thromboplastin, formed in a system lacking in factor VIII or IX. A study is also reported on the changes responsible for the stabilization with phenol of brain thromboplastic activity. The action is not purely bactericidal, but is dependent on the presence of brain tissue particles in suspension. The contribution of platelets to plasma thromboplastin formation is examined in the light of these investigations, showing the ability of phosphorus‐free compounds to supply a platelet‐like activity.
Segmented polyurethane: A polyether polymer. An initial evalution for biomedical applications
Authors: Boretos John W. , Pierce William S.
Published: May 2005

A segmented polyurethane elastomer, originally developed for elastic thread, is now being used for molded prostheses. Chemical, mechanical, and biological properties are described. Hydrolytic stability of this polymer is compared to that of a polyester urethan. Experience with the material used in components of an experimental heart‐assist pump has shown excellent flex endurance, wear resistance, and intravascular acceptability.
Oral and cutaneous tissue reactions to injected fluid silicones
Authors: Nedelman C. I.
Published: May 2005

During the period covered by this investigation, toxicological studies were carried out in hamsters and rabbits. The results of injections, subcutaneously and in the buccal pouch of hamsters, indicated that the silicones used were nontoxic, non‐absorbable, and well encapsulated by connective tissue elements with moderate tissue reaction. Further studies of various combinations of roomtemperature vulcanizing silastics indicated similar reactions when injected submucosally in the alveolar ridges and palate of rabbits. The injected materials remained in situ in the injected submucosal area and became well encapsulated by the proliferation of connective tissue and collagenous fibers. There was no evidence of macrophages or foreign body giant‐cells in and around the proliferating connective tissue capsule. There were no macroscopic or microscopic signs of tumor formation. The encapsulated masses did not elicit bone resorption when localized adjacent to bone tissue.
Determination of residual ethylene oxide in catheters by gas—liquid chromatography
Authors: Kulkarni R. K. , Bartak D. , Ousterhout D. K. , Leonard Fred
Published: May 2005

A quantitative method for determining residual ethylene oxide in plastic and rubber catheters using gas–liquid chromatography has been developed. Tests on ethylene oxide stabilized catheters indicated that the amount of ethylene oxide in the catheters decreased as a function of aeration time up to 48 hr. After this period, a steady concentration of ethylene oxide in the catheters appeared to have been reached up to one week's testing.
α‐Cyanoacrylate adhesive bond strengths with proteinaceous and nonproteinaceous substrates
Authors: Leonard Fred , Hodge J. W. , Houston Stuart , Ousterhout D. K.
Published: May 2005

The higher n‐alkyl α‐cyanoacrylate homologs had been previously found to wet, spread, and rapidly polymerize on tissue substrates whereas the lower homologs do not wet and polymerize slowly. The reverse effect is noted on nonproteinaceous substrates such as distilled water and saline solution. Tissue bonds were prepared and tested in vivo in rats. Bonds prepared with the higher n‐alkyl α‐cyanoacrylate homologs were found to be stronger than those prepared with the lower homologs. The data are in general accord with the wetting and spreading characteristics of the n‐alkyl α‐cyanoacrylate homologs. On aluminum surfaces, the opposite effect was noted. Bonds prepared with the lower homologs were stronger than those prepared with the higher homologs.
Semipermeable aqueous microcapsules (artificial cells). V. Permeability characteristics
Authors: Chang Thomas M. S. , Poznansky Mark J.
Published: May 2005

A rapid mixing and sampling technique was used to study the permeability characteristics of semipermeable aqueous microcapsules (artificial cells). Urea, creatine, creatinine, uric acid, glucose, sucrose, and salicylic acid equilibrated rapidly across nylon microcapsules of 207 μ diameter (e.g., T 1/2 for urea of 3.4 sec). From these results the permeability constants were calculated (e.g., P for urea of 2 × 10−4 cm/sec). Very much the same permeability constants were found for collodion microcapsules. The equivalent pore radius of the membrane of the nylon microcapsules were estimated to be 18 A.
Surgical suture–canine tissue interaction for six common suture types
Authors: Homsy C. A. , McDonald K. E. , Akers W. W. , Short C. , Freeman B. S.
Published: May 2005

Maximum extraction stress and integrated extraction work were measured for sutures implanted for 3, 7, and 14 day periods. Six common non‐absorbable sutures, representative of braided and monofilamentary forms, were implanted subdermally and were used for cutaneous incision closure with purebred pointer dogs. The data show: (1) Braided sutures, polyester/Teflon, silk‐type B, and silk–silicone interacted with peripheral tissue to a significantly greater degree than the monofilamentary types, nylon, polypropylene, and polyethylene; (2) polyester–Teflon braided suture interacted to a lesser degree than the other braided sutures; (3) the relatively intense interaction of plain silk and silicone‐treated silk appears to reflect the combined effects of mechanical aspects of braiding and of biochemical response; and (4) all braided sutures swelled over the implantation periods with as much as a 70% increase in diameter after 14 days for silk.
Enzyme entrapment within hydrophobic and hydrophilic matrices
Authors: Brown Harry Darrow , Patel Anil B. , Chattopadhyay Swaraj K.
Published: May 2005

ATP‐diphosphohydrolase, trypsin, and chymotrypsin have been insolubilized by lattice‐entrapment using hydrophilic polyacrylamide gel and hydrophobic Silastic matrices. The entrapped enzymes were stable and unaffected by washing or wet storage. Thermal inactivation properties of polyacrylamide‐entrapped ATP‐diphosphohydrolase were different from those of the same enzyme in solution. Several substrates were used for each of the proteolytic enzymes. Esterase activities of both trypsin and chymotrypsin were unaltered by entrapment within Silastic. The entrapment of enzymes and other active proteins is potentially of consequence in continuous‐flow substrate conversion systems. Silastic with a surface proteolytic activity derived from an entrapped enzyme is of possible medical utility for implantation elements.
Silastic entrapment of glucose oxidase–peroxidase and acetylcholine esterase
Authors: Pennington S. N. , Brown H. D. , Patel A. B. , Chattopadhyay S. K.
Published: May 2005

Acetylcholine esterase and the glucose oxidase–peroxidase systems have been entrapped in Silastic matrices. The entrapped acetylcholine esterase exhibited remarkable stability as compared to the free enzyme in solution. The glucose oxidase–peroxidase system indicated that consecutive reactions may be carried out by several enzymes entrapped within a single matrix. The effect of various inorganic materials on the entrapped enzymes was also investigated.
In vitro testing of silicone rubber heart‐valve poppets for lipid absorption
Authors: Carmen Raleigh , Kahn Paul
Published: May 2005

An in vitro procedure for measuring the affinity of silicone rubber balls for lipid is described. The method appears to duplicate weight and volume increases occasionally noted in vivo. Potential lipid absorption is shown to increase with degree of cure, and decrease with filler content.
Attachment of prostheses to the musculo‐skeletal system by tissue ingrowth and mechanical interlocking
Authors: Hulbert S. F. , Cooke F. W. , Klawitter J. J. , Leonard R. B. , Sauer B. W. , Moyle D. D. , Skinner H. B.
Published: May 2005

The concept of tissue ingrowth into porous biomaterials as a means of attaching prostheses to the musculo‐skeletal system is reviewed. A compilation of the various ceramic materials studied in vivo to date along with the results of the studies is presented. Results of studies on kinetics of tissue ingrowth into porous biomaterials are summarized. A discussion of the parameters controlling the rate of tissue ingrowth into porous implants is presented.
Methods of osseous reconstruction of the mandible following surgical resection
Authors: Boyne Philip J.
Published: May 2005

Osseous reconstruction of the surgically resected mandible has presented, for some time, a considerable surgical problem. This paper presents the results of a series of experimental investigations evaluating the various morphologic and immunologic types of autogenous bone grafts in the reconstruction of the surgically resected mandible. The osteogenic inductive effect of hemopoietic marrow in combination with autogenous cancellous bone is reviewed and examples of this inductive effect are cited. The application of the particulate graft of cancellous bone and marrow to the restoration of large areas of lost mandibular bone is described. In this application, the particulate graft is used with a compatible metal implant designed to offer an optimal grafting system for the reconstruction of large areas of the mandible. The metallic implant, in addition to containing the bone graft, serves to control and fix the host bone fragments and lessens the period of intermaxillary immobilization necessary for healing. Normal aesthetic mandibular contour is restored and routine dental prosthesis may be constructed over the reconstructed mandible. It is felt that this system offers the optimal approach, through the combination of implant metals and highly osteogenic graft tissues, to the reconstruction of the mandible following surgery.
Development of the self‐supporting polymer tooth implant
Authors: Hodosh Milton , Povar Morris , Shklar Gerald
Published: May 2005

The central theme of our studies is concerned with finding a better means of tooth replacement. This goal is being realized for a “tailor‐made” polymer and associated techniques of usage have been developed for this purpose. In the course of doing this, we have introduced the polymer implant concept by which materials can be tailor made to serve different functions.

The polymer composition currently considered best for these studies contains clear polymethacrylate powder and liquid monomer, blowing agent (dinitrosopentamethylene tetramine), anorganic bone, and N‐tributyl phosphate. This mixture is heat processed in a plaster mold at 300° F for 30 min. The processed implant is sandblasted to remove its outer skin and to open the pores on the implant's surface to the host's tissues when implanted. This formulary has resulted in the totally self‐supporting replica implant becoming a reality in baboons. Two Papio‐Anubis baboons', both with 8 incisors (4 upper and 4 lower) were replaced with polymer replicas, and after 3 months the splints were severed and the 16 implants remained totally self‐supporting. Metals have been coated with this polymer formula, and polymer coated pins have been used successfully as supports for fixed prostheses and as endodontic stabilizers. The internal metal piece imparts increased strength without bulk, while the polymer coating allows for attachment to the implant. The untoward effects of metals, such as heat transfer, electrical and corrosive phenomena are diminished or eliminated. This “happy union” of the two materials allows the implant to be strong and well integrated into the host. The Polymer Implant Concept holds a genuine hope for the future. In this instance it provides for a better means of tooth replacement: one which is cosmetically and functionally excellent. Most probably it will have an important place in the neurosurgical, orthopedic, and medical fields as well.
Implantable ceramic teeth
Authors: Hamner James E. , Reed O. M.
Published: May 2005

Identification of an appropriate biomaterial which would allow an artificial tooth implant to function in a stable manner without eliciting a toxic response is one of the major challenges facing dentistry today, and has been the subject of an increasing number of investigations in recent years.

Because of questions which still remain regarding the biocompatibility of candidate materials, extensive animal research in tooth implantation is an absolute necessity. Primates, providing dental models closely approximating the human condition, are especially valuable for undertaking that systematic scrutiny of experimental implant materials which is so clearly prerequisite to human clinical trials.

In the current study, 26 jaw block sections, containing calcium aluminate root implantations, were surgically removed from 13 baboons. The implantation time periods ranged from 2 weeks to 10 months. The controlled porosity of the ceramic roots varied from 50 to 200 μ.

Ingrowth of periodontal tissues into the porous ceramic root implants was demonstrable clinically, with light microscopy, and with the scanning electron microscope. Implant retention and stability, resulting from adequate ingrowth of fibrous/vascular elements into the ceramic pores, were optimal when the calcium aluminate root implants had a porosity of 100–150 μ. The problems of toxicity and biodegradability were not encountered using calcium aluminate.
The anchor oral endosteal implant
Authors: Cranin A. Norman , Dennison Thomas A. , Schnitman P. , Piliero S. , Pentel L.
Published: May 2005

Since the accidental rediscovery of the endosteal implant by Formaggini in the late 1940's, the field has witnessed a tremendous evolution in theory and clinical application. Chercheve, in his efforts to improve on earlier spiral designs, proposed several theories on the relationship of the metallic endosteal implant to its osseous environment. Some of the problems he experienced still have not been overcome in our present designs.

The development of the blade implant marked a true advancement in endosteal design. This implant proved to be much more functional and reliable than the spiral concept; however, it too had certain disadvantages which became obvious after a relatively short period of clinical trial. The anchor endosteal implant was developed as a result of efforts to correct the various problems associated with the blade.

Preliminary animal research using both anchor and blade implants was begun. Four dogs had each type of implant inserted in edentulous areas. The animals were sacrificed four months post insertion for histologic examination. More sophisticated animal implant studies are being performed at the Brookdale Hospital Medical Center.

Clinical evaluation of the anchor implant over a 3‐year period has been very encouraging. Results have indicated a higher level of clinical success than previously achieved with blade or spiral designs.
History and philosophy of attachment of prostheses to the musculo‐skeletal system and of passage through the skin with inert materials
Authors: Murphy Eugene F.
Published: May 2005

The history of passage through the skin and of attachment to bone to treat fractures is briefly sketched since the work of Malgaigne in 1843. Attachment of metal to bone for many months is now routine after open reduction of fractures and is quite successful for many years for completely buried hip prostheses. Passage through the skin, the gums, or the cornea has been used in many specialties. At least half a dozen investigators have attempted skeletal attachment of artificial limbs.

Even if absolute solutions are impossible, perhaps temporary successes might be extended by one or two orders of magnitude (adequate for a lifetime) by increased attention to engineering details. The role of ASTM Committee F–4, Surgical Implants, is noted. An important principle may be matching of stiffness, or at least tapering of the transition in stiffness, between implant and tissue. This precaution should reduce local stress concentrations tending to loosen attachment to bone or to reopen mechanical adherence of tissue to implant, opening a pathway for infection.
The fracture mechanics of bone—another look at composite modeling
Authors: Cooke Francis W. , Zeidman Howard , Scheifele Stephen J.
Published: May 2005

The energy absorbed in the impact fracture of bovine metatarsal and metacarpal bone was shown to depend on the aspect from which the inpact specimen was obtained. In a majority of cases caudad specimens were more than an order of magnitude tougher than cephalad specimens and the fracture surfaces of the tough specimens were fibrous or woody in appearance due to osteon pull out. This pull out phenomenon was identified as a major factor in determining the toughness of bone and is analogous to the toughening effect produced by fiber pull out in synthetic composites. Whenever a substantial component of the applied stress was resolved across the osteons, the fracture cracks were seen to propagate in an interosteonal mode similar to the delamination of synthetic composites with weak interfaces. Plastic deformation of the matrix is the third mechanism commonly employed to effect toughening in synthetic composites. Although no similar phenomenon was demonstrated in this study, it is probable that this also makes some contribution to the work‐to‐fracture of bone.
Design considerations in a rolamite knee joint prosthesis
Authors: Thornton A. W. , Predecki Paul
Published: May 2005

Problems encountered with existing total knee prostheses are briefly summarized. Existing prosthesis designs giving anatomically correct relative planar motion between femur and tibia are reviewed. A design incorporating a Rolamite suspension is proposed and evaluated. The design has the advantages of being closely anatomical in its motion having negligible friction or wear and requiring no lubrication. If substantial tendon damage is present the Rolamite design is easily modified to include a gear and rack.
Structure ‐ biocompatibility relationship of condensation polymers
Authors: Imai Y. , Watanabe A. , Masuhara E. , Imai Y.
Published: May 2005

Various condensation polymers including polyamides, polyesters, polyethers, polysulfonamides, polysulfonate, polyphosphonate, polyimide, polyamide‐imides, polyester‐amides, etc. have been prepared and evaluated for their biocompatibility by a cell culture method. Cell attachment and cell growth are influenced by the chemical structures of the tested polymers. Aliphatic polyamides exhibited considerably different cell growth behavior than aromatic polyamides.
Acrylate and methacrylate esters: Relationship of hemolytic activity and in vivo toxicity
Authors: Dillingham E. O. , Lawrence W. H. , Autian J. , Schmalz G.
Published: May 2005

Quantitative hemolysis assays of acrylate and methacrylate esters provided estimates of the intrinsic hemolytic activity (Hi the slope of the concentration‐response curve) and the concentrations effecting 5% (H5) and 50% (H50) hemolysis. The dependence of hemolytic activity and LD50 (mice) on physical properties (lipophilicity, molar refraction, and molecular volume) of the esters was determined by multiple regression analysis. The observed correlations were: Hi, R2 = 0.94; H5, R2 = 0.95; H50, R2 = 0.94; and LD50, R2 (all compounds) = 0.80, R2 (all compounds less the methyl esters) = 0.94. The difference of the methyl esters was associated with the smaller steric volume of the methyl ester substituent and the presence (methacrylates) or absence (acrylates) of the branched methyl group. Associative steric contributions of the branched methyl group and the ester substituents were probably responsible for greater variability in the methyacrylate series. The results were consistent with the conclusion that the mechanism of the action of the esters is membrane mediated and relatively nonspecific and that in vivo biotransformation was not a significant factor. Also, long‐term toxic liability of the esters may be more closely related to intrinsic toxicity than acute toxicity.
Stiffness and inelastic deformation in acrylic‐titanium composite implant materials under compression
Authors: Schnur D. S. , Lee D.
Published: May 2005

A variety of acrylic bone cement‐metal composite materials were prepared and tested in simple compression at 37°C in order to evaluate the mechanical behavior of these materials for possible use in bone replacement. The stiffness of the composite was of particular concern, and a simple rule of mixture was used to raise the modulus of acrylic bone cement. The reinforcement of the cement was accomplished by titanium and Ti‐6A1‐4V in different forms, e.g., wire, sheet, wire mesh, and powder. Test results demonstrated that the stiffness of the bone cement could indeed be increased by a desired amount to that of bone. A 16% volume fraction consisting of 25 0.10 cm diam Ti‐6A1‐4V wires increased the modulus of the bone cement by 380% to a value comparable to the modulus of cortical bone. Titanium sheet was nearly as effective as wires in increasing the modulus of bone cement, while titanium mesh was not a significantly effective reinforcing material. The amount of titanium powder added to the bone cement did not alter the compliance of the matrix material. In addition, as the flow strength increased, the strain to the point of load instability decreased. It was concluded that the extent of stiffening was governed by nonuniform deformation in the metal and the adjacent matrix which could be explained on the basis of geometrical considerations. Some of the limitations of the test results as well as methods of predicting the composite implant material behavior are also outlined.
Hyaluronan solution as a cartilage antidesiccant
Authors: Bloebaum R. D. , Rubman M. H. , Merrell M. , Thacker K. , Hofmann A. A.
Published: May 2005

During arthrotomy, desiccation of the articular cartilage of synovial joints by the ambient environment of the operating room causes chondrocyte death and may promote degenerative changes within the joint. This study documents the efficacy of a biomaterial, hyaluronan (HY) solution, to maintain chondrocyte viability during desiccation. Rabbit patellar articular cartilage was air‐dried for 2 h with and without application of the HY solution. As assessed by 35S04 uptake and autoradiography, the HY solution helped maintain chondrocyte viability, when compared to air dried specimens (p ≤ 0.02). HY solution applied to the articular surfaces of joints undergoing arthrotomy may offset the detrimental effects of desiccation, such as chondrocyte death and degenerative joint changes.
Preparation of poly (D, L) lactide microspheres by emulsion–solvent evaporation, and their clinical applications as a convenient embolic material
Authors: Grandfils C. , Flandroy P. , Nihant N. , Barbette S. , Jérome R. , Teyssié Ph. , Thibaut A.
Published: May 2005

The aim of preoperative embolization is to facilitate surgical removal by reducing tumor volume and vascularity, thereby decreasing blood loss during surgery. In a search for a better embolic material, compared to heterogeneous commercial products, we describe here in detail the preparation of poly (D,L) lactide microspheres by an emulsion‐solvent evaporation process. The size distribution of the microparticles and their aggregation state‐critical parameters in view of such application‐have been investigated. Their effectiveness, as an embolic material, has been evaluated by some preliminary experiments undertaken on humans. The results were assessed on clinical and histological grounds.
Mechanical properties of fibrin adhesives for blood vessel anastomosis
Authors: Flahiff C. , Feldman D. , Saltz R. , Huang S.
Published: May 2005

Various methods have been used for anastomosing, or attaching, two ends of a severed blood vessel together. The most common method, suturing, is tedious, can be time‐consuming, and requires special training in microvascular surgery. Other methods, such as mechanical devices and lasers, have some problems as well. The use of fibrin adhesives for blood vessel anastomosis might eliminate some of the current problems by allowing a quicker, simpler, and more reliable method of attachment. Although mechanical studies have been conducted to determine fibrin glue properties in shear, tensile, and burst tests; most of these studies have used skin or intestinal tissue. Therefore, to evaluate the feasibility of using fibrin glue as an adhesive for blood vessel anastomosis, the mechanical properties of blood vessels joined with fibrin glue were examined using tensile and burst tests. High and low fibrinogen concentrations were tested after 5‐ or 45‐min time periods. In addition, three clinical methods of attachment were compared: end‐to‐end anastomosis, vessel overlapping, and suturing. In this study, because the adhesive strength was not found to increase significantly after 5 min, setting times for fibrin glue may be short enough to make it a clinical option when compared to suturing. In addition, the higher fibrinogen concentration did not result in a significantly higher adhesive strength, indicating that the lower concentration fibrin adhesives may be of comparable strength to the higher concentrations for clinical applications.
The role of connective tissue in inhibiting epithelial downgrowth on titanium‐coated percutaneous implants
Authors: Chehroudi B. , Gould T. R. L. , Brunette D. M.
Published: May 2005

Ideally, the surface of epithelium‐pene‐ trating implants should impede apical epithelial migration. Previous studies have shown that micromachined grooved surfaces can produce connective‐tissue ingrowth, which inhibits epithelial downgrowth on percutaneous implants [Chehroudi et al., J. Biomed. Mater. Res., 24, 9, (1990)]. However, in those studies, connective tissue and epithelium interacted with the same surface so that the effects of the surfaces on each population could not be determined separately. The objectives of this study were (a) to examine cell behavior on implants in which connective tissue contacted surfaces of various topographies and epithelium encountered only a smooth surface, and (b) to compare one‐ stage and two‐stage surgical techniques. Implants had a base component (BC) which was either smooth or had a surface with 19‐pm‐ or 30‐pm‐deep grooves or 120‐pm‐ deep tapered pits, and a skin‐penetrating component (SPC) which was smooth. In the two‐stage technique, the BC was implanted subcutaneously for 8 weeks, which permitted the healing of the periimplant connective tissue. In the second stage the SPC was connected to the BC. For one‐stage implants, BC & SPC were connected and implanted percutaneously. Implants (BC & SPC) were removed 1, 2, or 3 weeks after percutaneous implantation and histological sections were measured for recession, connective tissue and epithelial attachment as well as capsule thickness. Light microscopy indicated that both grooved and tapered pitted surfaces encouraged connective tissue ingrowth. On the grooved surfaces, the orientation of fibroblasts changed from an oblique to a more complex pattern which included cells having round nuclei within the grooves, as well as cells oriented oblique or perpendicular to the grooves. In the tapered pits a hammock‐like arrangement of fibroblasts was observed. In some cases, foci of mineralization and formation of bonelike tissue were found on the grooved and pitted surfaces. The apical migration of the epithelium was significantly (p < 0.05) inhibited by those micromachined surfaces which produced connective tissue ingrowth to the BC. This study found that placing the implants in two stages improved the performance of percutaneous devices, and that a further improvement was achieved if the implant had a surface promoting connective tissue ingrowth.
Human gingival tissue response to HTR polymer
Authors: Yukna R. A. , Greer R. O.
Published: May 2005

Biopsies secured during reentry surgical evaluation of previously treated periodontal osseous defects were examined for gingival tissue response to HTR polymer. Eleven patients provided biopsies of HTR grafted sites 6‐7 months after initial implantation. Minimal inflammation and infrequent foreign body giant cells were found. Bone was present in about half of the samples and osteogenesis associated with the HTR graft material was seen in about 20% of the biopsies. Serendipitously, biopsies of other graft materials or debridement only sites from 6‐30 months post‐treatment were also available for analysis and comparison, and showed similar tissue response. The results of this study suggest that HTR polymer (and other graft materials) is very biocompatible and elicits no untoward gingival tissue responses when placed in periodontal osseous defects.