bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of extracorporeal shock wave lithotripter (ECSWL) in orthopaedics. II. Dose–response and pressure distribution measurements
Authors: Park J. B. , Park S. H. , Weinstein J. N. , Loening S. , Oster D.
Published: May 2005

In order to apply the extracorporeal shock wave lithotripter (ECWSL) technique to the loosening of the bone–cement interface for the extraction of the cement during revision arthroplasty it is essential to know the dose‐response characteristics. The present study shows that the number of shocks needed to break the interface between a 2‐ and 6‐mm‐thick bovine femoral bone and bone cement is similar to the fatigue behavior of a material, that is, Log(N) = C(kV) + D, where N is the number of shock impulses, kV is the power setting of the lithotripter machine in kilovolts, and C and D are constants. Iso‐pressure distribution of the traveling shock wave front through a simulated bone in a Plexiglass® tube using Fuji® pressure film showed quantitative pressure contours from which one can understand the effective area of shock wave and its distribution. The most effective area of the shock wave was about 1.5 cm in diameter at 23 and 25 kV with pressure at least 7.0 MPa which is more than sufficient to break the bone–cement interface in tension.
Applied Biomaterials Standards Report
Authors: Daniels A. U.“Dan”
Published: May 2005

The purpose of my column is to provide readers with current information on biomaterials related standards produced by both private groups and government agencies, and also on standards‐related activities. Standards are descriptive documents given official status by their producers, and in the case of biomaterials, they are generally intended to provide formalized descriptions, of (a) materials used in the construction of medical devices, (b) materials used directly in surgical repairs, (c) test methods to evaluate materials for such applications, and (d) methods for handling or processing such materials.

Please consider this column not only a place to obtain biomaterials standards information, but also a place to submit news of biomaterials standards developments in order to get the information before the public. This invitation extends to members of all professional organizations and government agencies in the United States and abroad who are active in standards development and would like specific activities or standards publicized. I will present the information in this column to the extent that allotted space allows.

At last, a caveat–since this is a column, it contains both factual information and opinions. I will make every effort to make it clear which is which. Also, as a frame of reference, please note that this column was written and submitted in June 1991.
Thrombus deposition on polyurethanes designed for biomedical applications
Authors: Wabers H. D. , Hergenrother R. W. , Coury A. J. , Cooper S. L.
Published: May 2005

Thrombogenicity was assessed by measuring the amount of 111In‐platelets and 125I‐fibrinogen deposited on the inner luminal surface of six polyurethanes for up to 60 min of blood contact in a canine ex‐vivo shunt model. Commerical and laboratory synthesized polymers were examined. Two of the commercially synthesized polyurethanes (Biostable PURs) do not contain ether linkages in the polymer backbone and have previously shown resistance to oxidative and hydrolytic degradation. Static contact angle measurements, dynamic contact angle measurements, and ESCA were used to characterize the surfaces of these polyurethanes. The effectiveness of an acetone extraction used to remove extrusion waxes from Pellethane 2363‐80A was similarly studied. Both Pellethane 2363‐80A and the ether‐free materials had relatively nonthrombogenic surfaces, as indicated by low platelet and fibrinogen deposition, making them potentially good candidates for biomedical applications.
Alkyl cyanoacrylates as space filling bone adhesives
Authors: Bhat S. , Askew M. J. , Njus G. , Smith D. J.
Published: May 2005

Higher chained alkyl cyanoacrylates have potential to function efficiently as space filling, hydrophobic, viscoelastic, biocompatible, and rapidly polymerizing bone adhesives. Hence they may be useful in applications where a void has to be filled, such as replacement of the intervertebral disc. To assess their applicability as space filling material in such an pplication, three alkyl cyanoacrylates; methoxyethyl cyanoacrylate, isobutyl cyanoacrylate, and isoamyl cyanoacrylate have been evaluated in this study. The bonding strength of these cyanoacrylates to bone in a space filling situation have been measured. The results indicate the bond strength of isoamyl cyanoacrylate (0.13 MPa) to be significantly (p < 0.05) lower compared with methoxyethyl cyanoacrylate (0.33 MPa) and isobutyl cyanoacrylate (0.37 MPa). There was no significant difference in the bond strengths of isobutyl cyanoacrylate and methoxyethyl cyanoacrylate.
The effect of a TCP–collagen implant on the healing of articular cartilage defects in the rabbit knee joint
Authors: Hogervorst Tom , Meijer Dirk W. , Klopper Pieter J.
Published: May 2005

Osteochondral defects in the rabbit knee were filled with a TCP‐collagen mixture. In the femoral condyles a fibrous tissue was formed in the defects similar to that seen in control defects. In the tibial plateau defects were made with penetration of the underlying epiphysis. Repair tissue was formed resembling articular cartilage. © 1992 John Wiley & Sons, Inc.
In vivo biocompatibility of an acrylic, fluoride‐releasing, anion‐exchange resin
Authors: Benton John B. , Zimmerman Barbara F. , Zimmerman Karl L. , Ralph Rawls H.
Published: May 2005

This study evaluated the biocompatibility of an unfilled, fluoride‐releasing acrylic resin by subcutaneous implantation in guinea pigs. The experimental fluoride resin was compared to a nonfluoride, dental pit and fissure sealant (DELTON) of similar composition. Thirty‐four male albino guinea pigs received four Teflon® tubes each, implanted in the dorsal area. The tubes were open at both ends, three contained the experimental fluoride resin and one held the nonfluoride resin. The tubes and surrounding tissue were excised in 1–2 cm blocks, by necropsy, at 14 and 84 days. Histological evaluation showed that inflammatory response was none‐to‐slight at 14 days for 95% of the fluoride and 100% of the nonfluoride specimens. Five percent of the fluoride specimens produced a moderate tissue response. At 84 days, inflammatory response was none‐to‐slight for 82.5% of the fluoride and 61.5% of the commercial nonfluoride specimens, while 17.5% of the fluoride and 38.5% of the nonfluoride specimens produced moderate tissue responses. Chi‐squared analysis and Fisher's Exact test revealed no statistically significant difference (p ≤ 0.05) in tissue response between the two resins at either 14 or 84 days. Hence it is concluded that the experimental, fluoride‐releasing resin produces a very mild subcutaneous tissue response and that its biocompatibility is comparable to that of a widely used nonfluoride dental resin. It can, therefore, be considered as having a high potential for biological safety as a dental restorative resin or adhesive, or for other biomedical applications. © 1993 John Wiley & Sons, Inc.
Comparative studies of the toxicity of standard reference materials in various cytotoxicity tests and in vivo implantation tests
Authors: Tsuchiya Toshie , Ikarashi Yoshiaki , Hata Hideyo , Toyoda Kazuhiro , Takahashi Michihito , Uchima Takao , Tanaka Noriho , Sasaki Toshi , Nakamura Akitada
Published: May 2005

Polyurethane films that contained various amounts of zinc diethyldithiocarbamate (ZDEC) and zinc dibutyldithiocarbamate (ZDBC) were prepared as standard reference materials (SRM). Using three cell lines of V79, L929, and Balb/3T3 cells, the cytotoxicity of the dithiocarbamates and the SRM films were compared by agar diffusion assay, filter diffusion assay, neutral red assay, cell growth assay, and colony assay. Among these in vitro cytotoxicity tests, colony assay was found to be the most sensitive method for detecting the cytotoxicity. The cytotoxic potentials of extracts from SRM films correlated well with the concentrations of ZDEC or ZDBC involved in SRM. When various rubber materials including SRM and surgical rubber latex materials were tested, cytotoxic potentials of these extracts were also correlated with the inflammatory tissue capsule thickness in short‐term implantation tests. On the basis of these results, the SRM is judged to be useful for validating test sensitivity, and comparing the correlation between in vitro and in vivo responses. © 1993 John Wiley & Sons, Inc.
The influence of flange compliance and mechanical loading on the tissue response to percutaneous devices
Authors: Tramaglini Dawn , Powers Dennis L. , Black Jonathan
Published: May 2005

The failure of most percutaneous devices (PD) is caused by infection initiated by a lack of a tight seal at the skin–device interface. This interface can be disrupted by both extrinsic and intrinsic forces. Many stress reduction methods have been proposed, the most common being the application of a subcutaneous flange. It is widely believed that the bending compliance of the flange plays a significant role in the success or failure of a PD.

A study was conducted to observe the effect of flange compliance on local host response in both a functional and nonfunctional setting. Two PDs having flanges with different bending rigidities were implanted percutaneously in goats (n = 8). After a healing period of 2 weeks, half of these devices were externally stimulated with a random load. All the implants were retrieved after 4 weeks and evaluated histologically.

The tissue capsule was significantly thicker and the incidence of severe fibrosis and/or necrosis was higher at the flange rim of the functional implants, irrespective of flange compliance. The more compliant devices were encapsulated with a thick fibrous capsule more frequently than the less compliant ones, irrespective of functional status. The more compliant devices also had a greater incidence of foreign body giant cells in the corner region and elicited severe acute inflammation at the corner and top of the flange more frequently than the less compliant implants. Numerous areas of degenerating foreign body giant cells accompanied with fibroblastic proliferation and dystrophic mineralization were identified in many of the capsules beneath the flanges.

It was concluded that the rigid implants elicited a more desirable tissue response than the compliant implants while the functional implants elicited a less desirable response than the nonfunctional ones. There was no synergistic or antagonistic relationship between the functional status of the device and flange compliance. © 1993 John Wiley & Sons, Inc.
Histological and histomorphometrical evaluation of the bone reaction to three different titanium alloy and hydroxyapatite coated implants
Authors: Jansen J. A. , van der Waerden J. P. C. M. , Wolke J. G. C.
Published: May 2005

The aim of this study was to investigate the bone response to three different types of titanium (Ti) alloys and hydroxyapatite (HA) coated titanium alloy by histological and histomorphometrical analysis. Therefore, implants made of these materials were inserted into the tibia of rabbits. Implantation times were 6 and 16 weeks. The histological evaluation included measurement of the amount of bone apposition and analysis of the bone reaction and interface characteristics around the implants. The results demonstrated no marked differences in bony reaction to the different implant materials. In addition, the HA coatings showed loss of thickness. © 1993 John Wiley & Sons, Inc.
Effects of ions in aqueous media on hydroxyapatite induction by silica gel and its relevance to bioactivity of bioactive glasses and glass‐ceramics
Authors: Li P. , Ohtsuki C. , Kokubo T. , Nakanishi K. , Soga N. , Nakamura T. , Yamamuro T.
Published: May 2005

Hydroxyapatite induction by a synthesized pure silica hydrogel was examined in various simulated body fluids (SBFs) having different magnesium, calcium, and phosphate ion concentrations as well as pH values. The silica hydrogel generated biologically active apatite on its surface by taking up calcium and phosphorous ionic groups from a surrounding SBF that was prepared to emulate the human plasma in inorganic composition. The induction period for apatite nucleation on the surface of the silica was largely decreased with the addition of a small amount of the calcium or phosphate ions to the SBF and with an increase in pH, but increased with the addition of magnesium ion. Bioactivity of bioactive materials like Bioglass® and glass‐ceramic A‐W was well interpreted in terms of the rate of apatite formation reflected in these results. Moreover, the results provide the basic knowledge for designing new bioactive materials. © 1993 John Wiley & Sons, Inc.
Corneal endothelium cell adhesion on intraocular lenses in vitro
Authors: Arciola Carla Renata , Cenni Elisabetta , Tarabusi Cristina , Caramazza Roberto , Pizzoferrato Arturo
Published: May 2005

An in vitro evaluation was conducted of the adhesion capabilities of rabbit corneal endothelial cells on intraocular lenses (IOLs) made of heparin‐coated polymethylmethacrylate (HSM‐PMMA). The concave endothelial surfaces of albino rabbit corneas were placed in contact in vitro with the convex surfaces of the optical side of HSM‐PMMA IOLs in 4‐day cultures. PMMA IOLs served as controls. After an incubation period, the preparations were examined via phase‐contrast microscopy and via inverted microscopy after staining with vital dye (neutral red), both with and without the cornea in place. After fixation and staining with Giemsa, the cells adherent on the lens were counted on five different microscopic fields. It was observed that the corneal endothelial cells adhered equally to heparin‐coated and untreated PMMA IOLs. © 1993 John Wiley & Sons, Inc.
A new bioactive glass–ceramic as a coating material on titanium alloy
Authors: Takatsuka Kazutaka , Yamamuro Takao , Kitsugi Toshiaki , Nakamura Takashi , Shibuya Tekehiro , Goto Tatsuya
Published: May 2005

Apatite–wollastonite‐containing glass–ceramic (A ‐ W · GC) has a strong ability to bond to bone and relatively high mechanical strength. Therefore, as a bulk material it has recently been applied clinically even in load‐bearing sites. In this study, we modified A–W · GC by altering its composition ratio with the removal of CaF2 and the addition of B2O3, and examined the potential use of the resulting new glass–ceramic as a material for coating on a titanium (Ti) alloy. The bioactivity of this new coating (NC) material and its bonding ability to bone were investigated mechanically and histologically. After implantation of the Ti alloy plate coated with this material into the tibiae of rabbits for 2, 3, 4, 8, and 25 weeks, a detaching test was performed. The detaching failure load of the NC plates was compared with those of A–W · GC plates, hydroxyapatite (HA) plates, and uncoated Ti alloy plates implanted in the same way. The failure load of NC was as high as that of A–W · GC for all periods, whereas it was significantly higher at 3 and 4 weeks than that of HA. Uncoated Ti alloy showed lower failure loads for all periods, differing significantly from the other materials. There was no breakage or detachment of the coating layer observed after the detaching test. Histological examinations by CMR, Giemsa surface staining, and SEM‐EPMA showed that NC bonded directly to bone without any intervening soft tissue layer. A calcium–phosphorus‐rich layer (apatite layer) was observed within the coating layer, as is the case in A–W · GC. These results indicate that this new glass–ceramic has earlier bone‐bonding ability and high mechanical strength, making it a promising coating material. © 1993 John Wiley & Sons, Inc.
Metallic wear debris in metal‐backed patellar failure
Authors: Stulberg Bernard N. , Merritt Katharine , Bauer Thomas W.
Published: May 2005

Eight patients with failure of metal‐backed patellar components were studied for evidence of intraarticular and systemic metal deposition. Seven of the eight patients had failure of a titanium‐based patellar component that then articulated with a cobaltchromium femoral component. One patient had articulation of a cobalt‐chromium patellar component against a cobalt‐chromium femoral component. All components failed by the same pattern of failure. Wearing of the ultra high molecular weight polyethylene was followed by displacement of the polyethylene and then metal‐to‐metal contact of the components.

Methods for analysis of the debris included light and electron microscopy of synovial tissue and electron dispersive x‐ray analysis (EDAX) of tissue. Graphite furnace atomic absorption spectroscopy (GFAAS) was done on synovial fluid and synovial tissue as well as urine and blood specimens taken at various times from implantation to patellar revision.

Massive deposition of metallic debris within the knee joint was documented both histologically and by GFAAS. Titanium levels reached as high as 2776 ppm (mg/L) in the synovial fluid and as high as 917 mg/g of synovial tissue. Elevation of all the pertinent metals was seen in the tissue and body fluids. Titanium and aluminum levels were the highest. Titanium levels in the serum generally were highest near the time of implant failure. Other metal elevations were variable and could not be related to the time of failure. Synovial fluid levels of all metals and serum levels of titanium are reflective of intraarticular generation of metallic debris.

This study demonstrates that in situations of failure of a device, massive intraarticular debris generation occurs and systemic transport will occur. To date no systemic consequences can be attributed to the deposition of debris and follow‐up urine and blood specimens suggest that debridement and revision of the failed device results in lowering of the ion levels. © 1994 John Wiley & Sons, Inc.
Chemical and mechanical degradation of UHMWPE: Report of the development of an in vitro test
Authors: Rimnac Clare M. , Burstein Albert H. , Carr James M. , Klein Robert W. , Wright Timothy M. , Betts Foster
Published: May 2005

Ultra high molecular weight polyethylene (UHMWPE), used in total joint replacement implants, undergoes oxidative degradation due to gamma radiation sterilization and to exposure to oxidizing agents in the body environment. UHMWPE components also experience large stresses both on and near the articulating surface. It is hypothesized that there is a causal relationship between chemical degradation and mechanical loading of UHMWPE joint components. This report describes the development of an in vitro test to examine the combined effects of chemical environment and cyclic loading history on the chemical, physical, and mechanical properties of UHMWPE. The test apparatus consists of modular load trains, in which strings of UHMWPE test specimens can be subjected to cyclic tensile and compression load ranges, while being exposed to either control or degrading environments. Following cyclic loading for specified time intervals, the specimens can be statically loaded to determine the effect of cyclic loading and environment on the monotonic tensile and compressive stress–strain behavior of UHMWPE. To determine the appropriate control and degrading environments, gamma radiation sterilized UHMWPE specimens were maintained (unloaded) for up to 6 months in aqueous environments of distilled water and three concentrations of hydrogen peroxide (0.01, 0.1, and 1.0%) in distilled water at 37°C. Specimens were evaluated with depth from the surface for changes in density. Infrared spectroscopy (IR) analysis was conducted on selected surface sections. No significant changes in density or surface IR spectra occurred for specimens in distilled water as compared with the UHMWPE in the initial radiation sterilized condition. Specimens exposed to hydrogen peroxide solutions demonstrated changes in density and IR spectra consistent with oxidative degradation and comparable to the changes previously observed on retrieved UHMWPE components. Based on these results, distilled water was selected for the control environment. A 0.5% hydrogen peroxide solution was selected for the test environment, to produce moderate changes at a rate compatible with the maximum 12‐month time period of the experiment. © 1994 John Wiley & Sons, Inc.
Incidence of infection and analysis of contributing factors in revision joint arthroplasty over a two‐year period
Authors: Merritt K. , Panigutti M. A. , Kraay M. J. , Brown S. A.
Published: May 2005

This study examined the incidence of infection and the contributing factors in 166 patients undergoing total joint revision surgery. Of these 32 (19%) had organisms grown from material taken at the local site at the time of revision surgery. Six of the culture‐negative patients were clinically suspected of having an infection. With the inclusion of these six, the total incidence of infection in these revision patients was 23%. This is not the incidence of infection in total joint surgery. This is the incidence of infection in patients undergoing revision surgery for whatever reason. The cause of infection in 53% of the cases was either Staphylococcus aureus or coagulase‐negative Staphylococci. The Gram‐negative bacteria were implicated in only five (15%) of the cases. Many of these infections (31%) were in patients who had had the implant for greater than 7 years. Only 15% of the infections were in patients who had the implant for less than 6 months with an additional 9% being revised in the first year. There were no clinical symptoms or underlying conditions, including allergy, that distinguished the infected from the noninfected group. The infection rate was somewhat higher with the cobalt chromium alloys, somewhat less in the uncemented devices, and somewhat higher in the patients with total knee replacements than those with total hip replacements. The histopathologic analysis revealed that the presence of polymorphonuclear leukocytes (PMNS) was correlated with infection, but most patients with infection had lymphocytes rather than PMNS indicative of a chronic infection. Thus the diagnosis of infection on the basis of histopathology needs to be carefully evaluated. The presence of PMNS is diagnostic for infection, but has a high number of false negatives. The histopathologic data and the data on implantation time indicate that most of these infections are chronic infections. © 1994 John Wiley & Sons, Inc.
Polyethylene wear debris and tissue reactions in knee as compared to hip replacement prostheses
Authors: Schmalzried Thomas P. , Jasty Murali , Rosenberg Andrew , Harris William H.
Published: May 2005

Differences in bearing surface conformity and wear mechanisms suggest that the polyethylene (PE) wear debris generated by total knee replacement (TKR) prostheses should be different than that in total hip replacement prostheses (THR). To address this issue, PE wear debris and the cellular response in periprosthetic tissues from 19 failed TKRs was compared to that from 24 failed THRs using polarized light microscopy and a semiquantitative grading system. The foreign‐body inflammatory reaction in the THR cases was characterized by plump macrophages with a diffuse cytoplasmic birefringence when examined under polarized light, indicating the presence of multiple submicron particles of PE. The majority of the PE particles were <1 μm in size and only a small fraction of the total were >10 μm. The foreign‐body inflammatory reaction in the TKR cases was characterized by giant cells with fewer macrophages. In the TKR specimens, the size range of PE particles was broader than in the hips. PE particles between 2 and 20 μm were frequent in TKR specimens; particles <1 μm in length were less common than in the THR specimens. Diffuse cytoplasmic birefringence was not a characteristic of the TKR cases. These histologic differences were so consistently distinct that the source of the specimen (i.e., from a THR or TKR) could be blindly determined by light microscopy. The size distribution of the PE wear particles in these cases indicate that THRs generate a higher number of submicron PE particles and relatively few large particles while TKRs generate a broader range of particles that includes fewer submicron particles. The observed differences in the cellular responses is likely a direct result of the differences in the spectrum of PE wear particles. These differences may in part account for differences in periprosthetic bone resorption and loosening in TKRs as compared to THRs. © 1994 John Wiley & Sons, Inc.
A new technique for quantitation of metal particulates and metal reaction products in tissues near implants
Authors: Blumenthal N. C. , Cosma V. , Jaffe W. , Stuchin S.
Published: May 2005

Tissue specimens retrieved from four regions adjacent to hip implants during revision surgery were subjected to a novel treatment to make possible the quantitative separation of residual metal particulates and metal reaction products (metal ions and metal‐protein complexes). The tissues were exposed to sodium hypochlorite solution that degraded and solubilized them, liberating metal reaction products and leaving behind metal wear particles, which were separated by centrifugation. Atomic absorption spectrophotometry was used to analyze the concentrations of the separated metal ions and wear particles. Co ion concentrations were 0.05 to 0.9 mM, Cr ion concentrations were 0.04 to 2.1 mM, and Ti ion concentrations were 0.30 to 0.60 mM. The weight of Co metal particles was 0.1 to 4.9 mg/100 mg tissue, of Cr metal particles 0.07 to 2.2 mg/100 mg tissue, and of Ti particles 0.09 to 5.2 mg/100 mg tissue; one black tissue sample contained 3333 mg Ti/100 mg tissue. No correlation was found between the concentrations of these two entities in the samples examined, probably due to the complex and varied processes creating them. The procedures discussed here will result in data that can help elucidate the separate contributions of metal reaction products and metal particulates to implant loosening. © 1994 John Wiley & Sons, Inc.
Chemical stress relaxation of polyglycolic acid suture
Authors: Hayes Michael J. , Lauren Mark D.
Published: May 2005

Chemical stress relaxation methods are employed to study chemical and mechanical factors influencing the degradation of uncoated polyglycolic acid (PG) sutures. Specially constructed instrumentation is used to study the kinetics of the load bearing capability of PG (DexonTM) 3‐0 sutures in hydrolytic solution. The effects of pH, temperature, strain rate, and initial load on the rate of chemical stress relaxation are presented. Data show how mechanical factors such as the rate of loading (related to the speed of knot tying), as well as the final tension, are related to the rate of structural degradation. Maximum stability is observed at approximately 40°C, with slower degradation both above and below this point. Results show that the slower and tighter the suture is pulled, the greater its ability to sustain tensile loads during hydrolysis. © 1994 John Wiley & Sons, Inc.
New advances in electronic devices for hole detection
Authors: Cox Mary Jude , Bromberg William J. , Zura Robert D. , Foresman Pamela A. , Morgan Raymond G. , Edlich Richard F.
Published: May 2005

Holes in surgical gloves are considered to be an important source of transmission of pathogens between surgeon and patient. Two new glove hole detectors have been devised to alert the surgeon to the presence of holes. These devices have been evaluated using six powder‐free and seven powdered varieties of surgical gloves that were either dry or exposed to hydration. Eight of the 13 surgical gloves hydrated rapidly with water, altering their resistance to the conduction of electricity. Because the Barrier Integrity MonitorTM only has a hydration monitor, 68 false positives occurred during the evaluation, indicating to the surgeon that he/she should change gloves unnecessarily because the glove had no hole. In contrast, the Surgic Alert MonitorTM (SAMTM) had a hydration alarm as well as a glove hole detection alarm. During the 104 tests, the SAMTM device showed no false positives. In the testing of five of the rapidly hydrating types of surgical gloves, the SAMTM device could not reliably detect holes. On the basis of this study, the SAMTM device, in conjunction with gloves that resist hydration, appeared to be a reliable hole detection monitor. © 1994 John Wiley & Sons, Inc.
Ciprofloxacin attachment to porous‐coated titanium surfaces
Authors: Dunn D. S. , Raghavan Srini , Volz R. G.
Published: May 2005

A simple and effective method for attaching ciprofloxacin HCl salt to the surface of porouscoated titanium based orthopedic materials was developed. The method utilizes the electrophoretic migration of both fine ciprofloxacin HCl particles and ciprofloxacin ions to deposit the antibiotic salt on a positively biased surface. The quantity of antibiotic deposited can be easily and effectively controlled by varying the time of deposition and applied voltage. In vitro tests have indicated that the antimicrobial activity of the treated surfaces is retained for a period of 5 days. The method allows a significant amount of antibiotic to be deposited and could theoretically be used to deliver antibiotics to the tissues surrounding prosthetic devices in order to prevent postoperative infections. © 1994 John Wiley & Sons, Inc.
Compressive stress relaxation behavior of irradiated ultra‐high molecular weight polyethylene at 37°C
Authors: Waldman Stephen D. , Bryant J. Timothy
Published: May 2005

The preconditioned stress relaxation behavior of irradiated ultra‐high molecular weight polyethylene (UHMWPE), a commonly used bearing surface in total joint replacements (TJR), was modelled in uniaxial compression at 37°C. Twenty cylindrical specimens (10 mm dia. × 27 mm length) were machined from a compression molded plate of medical grade UHMWPE and γ‐irradiated to a minimum dose of 2.5 Mrad. At an initial strain rate 1000%/s, five specimens were each tested at constant strains of 1, 2, 5 and 10%. The modified superposition principle provided a good agreement of the nonlinear viscoelastic (stress relaxation) behavior of UHMWPE (standard error of 0.0753 MPa). © 1994 John Wiley & Sons, Inc.
Effects of fixation technique on displacement incompatibilities at the bone–implant interface in cementless total knee replacement in a canine model
Authors: Berzins Aivars , Sumner Dale R. , Turner Thomas M. , Natarajan Raghu
Published: May 2005

Bone–implant displacements can be caused by rigid body motion and by differences in material properties of the implant and bone. In the present study of the tibial component in total knee replacement, we tested a series of tibial component fixation designs to determine how certain design features influenced the magnitude of the tangential displacement between the component and supporting bone in a canine model. The transverse expansion of the proximal tibia under static axial loading was measured in the intact tibia and then in the same bone following implantation of tibial components with different interface characteristics: cementless flat smooth, cementless flat porous‐coated, cementless flat porous‐coated with screws, cementless pegged porous‐coated, cementless pegged porous‐coated with screws, cemented pegged, and cemented pegged with screws. In all cases, the magnitude of the transverse expansion increased with higher applied loads. When the statistical analysis was restricted to the cementless interfaces, the presence/absence of the porous coating, the presence/absence of pegs, and the use of screws had no significant influence on tibial expansion. However, in an analysis including the cemented and cementless pegged components, tibial expansion was reduced with the use of screws. The magnitude of the interface motion due to these displacement incompatibilities was approximately fivefold lower than the amount of interface motion related to rigid body motion found in a separate study with the canine model. The measured expansion was similar in the intact tibiae and the implanted tibiae, suggesting that the transverse constraint in the canine proximal tibia must be provided by the surrounding cortical ring rather than the subchondral bone. © 1994 John Wiley & Sons, Inc.
Adsorption of collagenase to particulate titanium: A possible mechanism for collagenase localization in periprosthetic tissue
Authors: Kane Kevin R. , DeHeer David H. , Owens Scott R. , Beebe John D. , Swanson Alfred B.
Published: May 2005

Osteolysis is a central feature of aseptic loosening of orthopaedic joint prostheses. This destructive process is believed to result from phagocytosis of implant wear debris by periprosthetic and synovial macrophages and the subsequent release of proinflammatory mediators, including collagenase. Isolated murine macrophages were cultured in vitro with particulate titanium in order to explore the mechanism of macrophage activation by particulate wear debris. The results, in which the amount of secreted, soluble collagenase in culture supernatants was inversely proportional to titanium concentration, suggested that titanium strongly adsorbed secreted collagenase. This inference was confirmed by direct binding assays in which particulate titanium coated with adsorbed collagenase bound an alkaline phosphatase conjugated anticollagenase antibody, but not a conjugated anti‐IgG antibody. Adsorption of collagenase was not influenced by preincubation of titanium particles with albumin. The adsorbed collagenase remained enzymatically active as indicated by its ability to hydrolyze a synthetic peptide substrate. These results demonstrate that particulate titanium stimulates collagenase production by macrophages and then strongly adsorbs the secreted proinflammatory enzyme. The process of macrophage stimulation, collagenase secretion, and adsorption may represent an important mechanism for localization and concentration of collagenase in periprosthetic and synovial tissue, a mechanism that ultimately triggers bone resorption through osteoclast activation. © 1994 John Wiley & Sons, Inc.
Histological and mechanical comparison of hydroxyapatite‐coated cobalt‐chrome and titanium implants in the rabbit femur
Authors: Friedman Richard J. , Bauer Thomas W. , Garg Kamil , Jiang Ming , An Yuehuei H. , Draughn Robert A.
Published: May 2005

The purpose of this study was to compare hydroxyapatite (HA)‐coated titanium (Ti) and HA‐coated cobalt‐chrome (CoCr) implants in the distal femur of the rabbit by evaluating bone apposition and interfacial shear strength. Bilateral cylindrical implants with a plasma sprayed 50‐m̈m thick HA coating were press‐fit into the metaphyseal cancellous bone of the lateral femoral condyles in a transverse fashion, and the animals were sacrificed at 2, 4, and 8 weeks postimplantation. Mechanical strength of the interface between HA and bone was measured using the pushout method. For histologic analysis, the fractional linear extent of bone apposition was quantitated. No differences were found in the interfacial shear strength between the Ti and CoCr at any time period. The amount of bone apposition increased significantly at each time interval for both substrate metals, but there were no significant differences between the two substrates at any of the time periods studied. The HA‐coated CoCr implants performed in a similar manner to the HA‐coated Ti implants, both mechanically and histologically, suggesting that HA‐coated CoCr implants deserve further study as a viable alternative to Ti for the biological fixation of total joint components in orthopaedic surgery. © 1995 John Wiley & Sons, Inc.
Practical aspects of Pt/Ir effluent splitters for multidetector GC and pneumatic solute switching
Authors: Anderson E. L. , Bertsch W.
Published: May 2005

Practical details are given to produce low dead volume Pt/Ir to glass connections and a variety of components for effluent splitting and pneumatic solute switching. It is shown that the column effluents from a glass capillary column can be split in any desired ratio and maintained constant, regardless of column flow rate. Bandbroadening in the splitter remains negligible even for very low flow rates. A complex pneumatic system to be used for heartcutting with two glass capillary columns is shown.
High performance liquid chromatography of terpenoids
Authors: Baas Wim J. , Niemann Gerard J.
Published: May 2005

HPLC‐separation using a reversed‐phase system is described for phytosterols, pentacyclic triterpenoid acids, ‐diols and –ketones.
Whisker surfaces in (GC)2
Authors: Sandra P. , Verstappe M. , Verzele M.
Published: May 2005

Growing whiskers on the inner wall of glass capillary columns is an easy roughening technique which allows efficient coating of the columns with any stationary phase. The advantages and disadvantages of whisker surfaces are discussed. Several examples are presented to illustrate the possibilities of whisker‐wall coated open tubular (WWCOT) columns.
Interpretation of the real plate number concept: A fundamental analysis
Authors: Smuts T. W. , Buys T. S. , de Clerk K. , du Tolt T. G.
Published: May 2005

The real plate number concept is interpreted in terms of the fundamental properties of a chromatograph. It is shown that the linear relationship between the total peak width at half height, (b0.5)T, t, and k is only an approximation of the more general linear relationship between (b0.5)2T, t and (1 + k)2. In the case where the relationship between (b0.5)T, t and k approaches linearity, it is concluded, firstly, that b0 = a, i. e., b0 is a column property and independent of extra‐column phenomena and, secondly, that nreal=ntheor. When the relationship becomes non‐linear, b0 is determined partly by extra‐column phenomena, but not in terms of a useful relationship. It is concluded that it is unnecessary to introduce the parameters a, b0 and nreal, since they all have counterparts in the established theory of chromatography. These counterparts prove to be equally useful in the practical analysis of chromatographic systems.
Analysis of volatile fatty acids by gas chromatography separation of benzyl esters
Authors: Liardon Rémy , Kühn Ursula
Published: May 2005

Volatile fatty acids in aqueous media were esterfied in situ with phenyldiazomethane (PDM). Complete esterification was achieved in 3 h at 40°C under continuous stirring of an ether/water system. The process involved immediate transfer of benzyl esters into the organic phase. The separation of benzyl esters mixtures was carried out in glass capillary GC columns. The retention data and FID molar responses were determined for C1 to C6 acid benzyl esters, including 2‐methylpropionic, 3‐methylbutyric, 2‐methylvaleric, and 2‐ethylbutyric acid. An unusual relationship was observed between benzyl ester relative molar responses and carbon atom number.
Preparation of apolar glass capillary columns by the barium carbonate procedure
Authors: Grob K. , Grob G. , Grob K.
Published: May 2005

As an extension of previous reports, the barium carbonate procedure has been optimized in detail for the preparation of apolar columns. The aim was to produce optimum overall column characteristics, and to maintain them unchanged under the prolonged influence of the highest possible temperature. The main parameters under optimization were glass variety, leaching of glass surface with aqueous HCl, and amount of barium carbonate deposited, while deactivation and coating were kept constant. The basic column characteristics were adsorption properties and thermostability of deactivation, acid/base behaviour and separation efficiency. They were determined by a new, quantitative testing procedure. Intense leaching was able to eliminate almost totally the differences between glass varieties and to create a well‐defined glass surface. While untreated glass, leached glass, and barium carbonate treated glass showed specific weak points in the respective column quality, the combination of leaching and barium carbonate treatment yielded the highest and most stable quality. Some technical modifications of the preparation procedure are described, including deactivation in the gas phase, and use of pentane as a solvent for static coating.
Some LC experiments with capillary columns
Authors: Dewaele C. , Verzele M.
Published: May 2005

Some experimental results of LC in capillary columns are presented. The possible effect of turbulence which has been much emphasised lately is overrated. The future of LC in capillary columns lies in extreme miniaturization.
Surface modified wall coated open tubular columns: Development and application in pesticide analysis
Authors: Onuska F. I. , Comba M. E.
Published: May 2005

Filamentary crystal growth on the inner surface of a glass analytical capillary column using a modified ammonium hydrogen difiuoride procedure, produced highly efficient wall coated open tubular columns.

Baseline separation of the acetate derivatives of 2,3,4,6‐ and 2,3,5,6‐tetrachlorophenol was achieved and was instrumental in determining pentachlorophenol loadings along a watershed. The application of capillary columns, related to the analyses of organochlorine pesticide residues is also demonstrated. Parent and degradation products of twenty‐five commonly monitored residues were effectively resolved on a 20 MOV‐101 column.
Continuous TLC as a pilot technique for optimization of gradient HPLC. 1. Theoretical considerations for stepwise gradient TLC with binary mobile phase
Authors: Golkiewicz W. , Jaroniec M.
Published: May 2005

Equations describing gradient elution in TLC, with a mobile phase of a constant composition in each step, have been derived. These equations are useful for calculating retention volumes from isocratic TLC data. Equations originally derived for gradient HPLC were adapted for TLC. The validity of the equations has been experimentally verified. The satisfactory agreement between experiment and theory for binary mobile phase composed of methyl ethyl ketone and n‐heptane suggests that TLC can be used as a pilot technique for gradient HPLC.
The HPTLC separation of malondialdehyde from peroxidised linoleic acid
Authors: Gutteridge J. M. C.
Published: May 2005

Peroxidised linoleic acid reacts with acidified thiobarbituric acid to give a chromogen absorbing maximally at 532 nm. This TBA reactant is chromatographically identical to the TBA‐MDA adduct formed from linolenic acid and a pure MDA standard. Considerably less MDA is produced by peroxidised linoleic acid compared to that formed from linolenic acid. In this respect the type of acid used for the colour reaction appears to be important.
A simple terminator for high efficiency liquid chromatography columns
Authors: Heath R. R. , Proveaux A. T. , Tumlinson J. H.
Published: May 2005

A comparison is made between a flat bottom column terminator and a cone terminator on. 1.27 cm O.D. and 2.54 cm O.D. columns. The cone terminator results in a doubling of the column efficiency, is simple and inexpensive, and is universally adaptable to any diameter column.
Analysis of polynuclear aromatic hydrocarbons by glass capillary gas chromatography using simultaneous flame ionization and electron capture detection
Authors: Bjorseth Alf , Eklund GÖRan
Published: May 2005

The possibility of simultaneous application of an electron capture (ECD) and a flame ionization detector (FID) connected to a glass capillary column for analyzing polynuclear aromatic hydrocarbons (PNA) has been investigated. The ECD/FID ratio is determined for 46 PNA compounds. The ratios vary from 0.02 to 117 with relative standard deviations better than 20 percent determined from 10 replicate analyses. The results suggest that the method may be used for obtaining additional evidence in identifying PNA in environmental samples.

Impurities and transformation products in the standard were identified by computerized glass capillary gas chromatography/mass spectrometry. Quinones and diones are responsible for the high EC‐response determined in some trace components in the standard.

An application of the method is shown for PNA from particulates in urban atmospheres.
Thermodynamic interactions of polypropylene, poly(vinylidene chloride), sulphonyldiphenyl formaldehyde resin and poly(vinyl pyrrolidone) as stationary phases in GLC with some selected solvents
Authors: Abushihada A. M. , Shunbo F. E. , Al‐Sultan Y. Y.
Published: May 2005

The interaction energies (X1) between the polymers polypropylene, poly(vinylidene chloride), sulphonyldiphenyl formaldehyde resin and poly(vinyl pyrrolidone) and the solvents toluene, ethylbenzene, isopropylbenzene, ortho, meta, and para‐xylene are determined by gas chromatography. As shown in earlier publications, this technique for the determination of X1, can be extended to similar systems of theoretical as well as of practical importance, although the selection of the present systems was primarly made on the fact that these systems are of industrial interest and have not so far been investigated by gas‐liquid chromatography. The studies were carried out at two temperatures and the results obtained show a decrease of X1 with an increase of temperature.
Determination of the 7‐amino‐metabolites of the 7‐nitro‐benzodiazepines in human plasma by thin‐layer chromatography
Authors: Haefelfinger P.
Published: May 2005

A sensitive thin‐layer chromatographic method is described for the determination of the 7–amino‐metabolites of flunitrazepam and clonazepam. The same procedure is applicable to other 7‐nitro‐benzodiazepines such as nitrazepam. A purified plasma extract of the 7‐amino‐metabolites is separated by thin‐layer chromatography. The primary aromatic amines are diazotized and coupled with N‐(1‐naphthyl) ethylene‐diamine on the thin‐layer plate. The quantities of the 7‐amino‐metabolites are directly evaluated by colorimetric densitometry. The lower limit of detection is in order of 0.5–10 ng cm−3 of plasma. The relative standard deviation of the whole procedure is less than ±15% in the range of 0.5–10 ng cm−3 for a single determination.

The unchanged drugs can be reduced on the thin‐layer plate and detected by the same method. Since this procedure is rather difficult to perform, it is advantageous to determine the 7‐nitro‐benzodiazepines in plasma by gas chromatography.

The thin‐layer chromatographic method was used to measure the 7‐amino‐metabolites in plasma of patients on either a flunitrazepam or a clonazepam oral dosing regimen.
The application of flow switching rotary valves in two‐dimensional high resolution gas chromatography
Authors: Miller Roger J. , Stearns S. D. , Freeman R. R.
Published: May 2005

Two‐dimensional high resolution gas chromatography with small bore glass capillary columns is simplified by use of a single 6–port flow switching rotary valve. The band spreading and tailing normally associated with mechanical valves is overcome by matching the internal valve passage diameters to that of the capillary column, and by minimizing unswept volumes in the fittings. selection of inert valve and transfer line materials effectively ellminates undesirable adsorption phenomena. The high thermal stability of the value permmits it to be mounted directly in the GC oven where it can be actuated externally. With slight modifications either packed or capillary pre‐columns may be used for initial saperations. Application of enrichment, solvent removal and heart cutting are described.