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PubMed1990

Long-term comparison of the electrical characteristics of polyurethane and polyethylene insulated ventricular leads.

Two types of pacing leads with different insulation material, polyurethane, and polyethylene, were followed for 44 months with respect to their electrophysiological characteristics and complications. In 48 patients, 32 polyurethane leads (Lifeline 493-03) and 16 polyethylene leads (EMT 588 D) were implanted and connected in all cases to the same type of programmable ventricular inhibited (VVI) pulse generator (Programalith, Pacesetter). There was a significant fall during the follow-up in lead impedance with the polyurethane leads (495 +/- 62 to 444 +/- 58 ohms, P less than 0.01), whereas the corresponding measurements for the polyethylene leads were essentially unchanged (360 +/- 58 to 378 +/- 71 ohm, ns). The energy of the stimulation threshold tended to increase in the polyurethane group, whereas an opposite tendency was observed in the polyethylene group. Pacing and/or lead failures were not observed in any case. The observed fall in impedance with the polyurethane leads was seemingly of no clinical significance.

Aged↗

PubMed1978

Immediate and delayed allergic contact reactions to polyethylene glycol.

The lower molecular weight liquid polyethylene glycols (PEG) varying from 200 to 700 are extensively used as solvent vehicles in topical medicaments. Four patients showed allergic reactions to these liquid polyethylene glycols in topical medications. Two had immediate urticarial reactions to PEG 400. Two other patients had delayed allergic eczematous reactions, one to PEG 200, and one to PEG 300. Cross reactions occurred between PEG 200, 300 and 400, but not between these liquid polyethylenes and the higher molecular weight solid polyethylenes from 1000 to 6000.

Adult↗

PubMed1988

Fermentative degradation of nonionic surfactants and polyethylene glycol by enrichment cultures and by pure cultures of homoacetogenic and propionate-forming bacteria.

Linear alkyl ethoxylates (polyethylene glycol alkyl ethers) were fermented completely to methane and CO2 in enrichment cultures inoculated with anoxic sewage sludge. Long-chain fatty acids were released as intermediates. No degradation was found with polypropylene glycol and polypropylene glycol-containing surfactants. Two types of primary ethoxylate-degrading bacteria were isolated and characterized. Both degraded polyethylene glycols with molecular weights of 1,000 completely. Strain KoB35 fermented polyethylene glycol, ethoxyethanol, and lactate to acetate and propionate and was assigned to the described species Pelobacter propionicus. Strain KoB58 converted polyethylene glycol and many other substrates to acetate only and was assigned to the genus Acetobacterium. The pathways of anaerobic degradation of nonionic surfactants are discussed with respect to their limitations and the various groups of bacteria involved.

Bacteria, Anaerobic↗

PubMed1985

Improved method for isolation and growth of Chlamydia trachomatis in McCoy cells treated with cycloheximide using polyethylene glycol.

The sensitivity of non-replicating McCoy cells pretreated with polyethylene glycol for the isolation of Chlamydia trachomatis from clinical specimens and for the growth of a laboratory strain was compared with the sensitivity of untreated non-replicating cell cultures. The concentration of polyethylene glycol in different solutions and the time of addition to the cell culture medium were critical. A concentration of 35% polyethylene glycol in barbitone added to the cell culture growth medium either immediately before or immediately after infection with chlamydia increased the number of inclusions detected. The rate of isolation obtained from clinical specimens was also increased when cell cultures treated with polyethylene glycol were used.

Bacteriological Techniques↗

PubMed1993

Immobilization of glucose oxidase on polyethylene film using a plasma induced graft copolymerization process.

An active glucose oxidase immobilized membrane was obtained via plasma induced graft copolymerization of acrylic acid on polyethylene film. Plasma induced graft copolymerization of acrylic acid on polyethylene film has been prepared. This novel grafted polymer film for immobilizing glucose oxidase has been studied here. The carboxylic groups of the poly(acrylic acid) chains incorporated onto the polyethylene surface were utilized for further chemical immobilization of glucose oxidase by esterification. The influence of plasma conditions such as plasma treatment gases, power, pressure, and time on the activity of the enzyme immobilized membrane has been determined. ESCA was used for analyzing the plasma treated polyethylene films and plasma induced grafted copolymerization products so as to obtain the optimum conditions for the immobilization of bioactive materials. The introduction of carboxylic acid groups onto a hydrophobic support has provided a good environment for enzyme bioactivity. The hydrophilicity of the grafted film and the activity of the enzyme membrane were proportional to the grafted amount. The glucose oxidase immobilized membrane shows no shift of optimum pH but do exhibit changes of pH-activity curve. The glucose oxidase immobilized membrane was shown here to be less pH sensitive than the soluble one.

Acrylic Resins↗

PubMedDate not supplied

Histopathological safety evaluation of polyethylene glycol applied subcutaneously in mice.

Polyethylene glycol is used as a non-aqueous solvent for a variety of medical agents. We believe it could also be used as a base component in root canal filling material and aimed to test the histological safety of subcutaneously injected polyethylene glycol. We injected polyethylene glycol subcutaneously into the dorsal area of 30 6-week-old anaesthetized male ddY mice. An equal number of mice were injected with propylene glycol as controls. One week, 3 weeks and 9 weeks after injection, the tissue surrounding the injection site was removed from 10 mice in each group and examined. We found no histopathological changes, degeneration, necrosis, foreign body reactions or granulation tissue proliferation in either group. Some inflammatory cell infiltration was observed in both groups. Based on these results, we believe that polyethylene glycol could be used safely as a base component of biomaterials for internal medical use, such as in root canal filling material.

Animals↗

PubMed1997

Charnley wear model for validation of hip simulators--ball diameter versus polytetrafluoroethylene and polyethylene wear.

Wear rates of polytetrafluoroethylene (PTFE) and polyethylene cups were compared in 9-channel and 12-channel simulators, using serum lubrication and gravimetric techniques for wear assessment. Cobalt-chromium (CoCr) and alumina ceramic femoral heads in 22-42 mm diameter range were used to validate simulator wear rates against clinical data. This was also the first study of three femoral head sizes evaluated concurrently in a simulator (with three replicate specimens) and also the first report in which any wear experiments were repeated. Fluid absorption artefacts were within +/-1 per cent of wear magnitude for PTFE and +/-8 per cent for polyethylene and were corrected for. Wear rates were linear as a function of test duration. Precision within each set of three cups was within +/-6 per cent. The wear rates from experiments repeated over 15 months were reproducible to within +/-24 per cent. However, the magnitudes of the simulator wear rates were not clinically accurate, the PTFE wear rates (2843 mm3/10(6) cycles; 22 mm diameter) were over three times higher than in vivo, the polyethylene 30 to 50 per cent on the low side (23 mm3/10(6) cycles; 22 mm diameter). Volumetric wear rate increased with respect to size of femoral head and a linearly increasing relationship of 7 8 per cent/mm was evident with respect to femoral head diameter for both PTFE and polyethylene. These data compared well with the clinical data.

Aluminum Oxide↗

PubMed1997

The role of polyethylene wear in joint replacement failure.

Aseptic loosening is the major cause of failure of joint replacement prostheses. Polyethylene implants removed at revision surgery regularly show wear. It is proposed that the polyethylene particles released into the tissues as a consequence of this wear induce a tissue response that precedes aseptic loosening. This paper presents the results of recent in vivo and in vitro studies of the biological response to polyethylene wear particles undertaken in the authors' laboratories. A clinical perspective is provided by the inclusion of the authors' recent observations of retrieval analyses of joint replacement implant wear and the tissue response to polyethylene in humans.

Animals↗

PubMed1999

Type of motion and lubricant in wear simulation of polyethylene acetabular cup.

The wear of ultra-high molecular weight polyethylene, the most commonly used bearing material in prosthetic joints, is often substantial, posing a significant clinical problem. For a long time, there has been a need for simple but still realistic wear test devices for prosthetic joint materials. The wear factors produced by earlier reciprocating and unidirectionally rotating wear test devices for polyethylene are typically two orders of magnitude too low, both in water and in serum lubrication. Wear is negligible even under multidirectional motion in water. A twelve-station, circularly translating pin-on-disc (CTPOD) device and a modification of the established biaxial rocking motion hip joint simulator were built. With these simple and inexpensive devices, and with the established three-axis hip joint simulator, realistic wear simulation was achieved. This was due to serum lubrication and to the fact that the direction of sliding constantly changed relative to the polyethylene specimen. The type and magnitude of load was found to be less important. The CTPOD tests showed that the subsurface brittle region, which results from gamma irradiation sterilization of polyethylene in air, has poor wear resistance. Phospholipid and soy protein lubrication resulted in unrealistic wear. The introduction of devices like CTPOD may boost wear studies, rendering them feasible without heavy investment.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1992

Interaction between polyethylene films and bromhexine HCl in solid dosage form. IV. Prevention of the sorption by addition of magnesium aluminum silicate.

The effects of magnesium aluminum silicate (MAS) addition on the sorption of bromhexine HCl to polyethylene film in tablets were studied. The addition of MAS prevented the sorption of bromhexine HCl to polyethylene film. In order to investigate the mechanism, the interaction between bromhexine HCl and MAS was studied by the powder X-ray diffraction method. It was observed that bromhexine HCl was preferentially adsorbed to the surface of MAS rather than to polyethylene film. The adsorption was accelerated at high temperature and reduced pressure conditions. The sorption of bromhexine base and bromhexine HCl to packaging material were compared using tablet dosage forms. The sorption of bromhexine base to polyethylene film was greater than that of bromhexine HCl.

Aluminum Compounds↗

PubMed1990

[Interaction between polyethylene films and brombexine HCl in solid dosage form. II. Effects of moisture property on the sorption of the drug].

The interaction between bromhexine HCl and polyethylene containers was studied in solutions and in tablet packaging systems. Various bromhexine HCl aqueous solutions of different pHs were stored in polyethylene containers at 25 degrees C. The remaining amount of bromhexine HCl was determined by high performance liquid chromatography. It was observed that the transition of bromhexine HCl to polyethylene was inhibited by the addition of some surfactants into the solution, and by lowering the solution pH. In the solid dosage forms, influences of the additives were also studied. It was observed that the decrease of the content of bromhexine HCl in the solid dosage form was inhibited by the addition of acids (citric acid, tartaric acid) and surfactant (sodium dodecyl sulfate) and accelerated by the addition of sodium bicarbonate, similarly to those in solutions. The results indicated that the transition to polyethylene films was influenced by the molecular state of bromhexine HCl.

Adsorption↗

PubMed2006

Should we reconsider all-polyethylene tibial implants in total knee replacement?

The role of modular tibial implants in total knee replacement is not fully defined. We performed a prospective randomised controlled clinical trial using radiostereophotogrammetric analysis to compare the performance of an all-polyethylene tibia with a metal-backed cruciate-retaining condylar design, PFC-Sigma total knee replacement for up to 24 months. There were 51 patients who were randomised into two treatment groups. There were 10 subsequent withdrawals, leaving 21 all-polyethylene and 20 metal-backed tibial implants. No patient was lost to follow-up. There were no significant demographic differences between the groups. At two years one metal-backed implant showed migration > 1 mm, but no polyethylene implant reached this level. There was a significant increase in the SF-12 and Oxford knee scores after operation in both groups. In an uncomplicated primary total knee replacement the all-polyethylene PFC-Sigma tibial prosthesis showed no statistical difference in migration from that of the metal-backed counterpart. There was no difference in the clinical results as assessed by the SF-12, the Oxford knee score, alignment or range of movement at 24 months, although these assessment measures were not statistically powered in this study.

Aged↗

PubMed1999

Expression of gelatinase A and its activator MT1-MMP in the inflammatory periprosthetic response to polyethylene.

Wear debris of polyethylene prosthetic components is known to induce a host granulomatous reaction which recruits numerous macrophages and multinucleated giant cells. By releasing cellular mediators of a nonspecific inflammatory reaction, activated phagocytic cells are thought to play a key role in osteolysis leading to aseptic loosening of the prosthesis. Matrix metalloproteinases (MMPs) have been implicated in this destructive process by their ability to degrade extracellular matrix components of bone and adjacent connective tissue. To investigate the roles of gelatinase A, its activator MT1-MMP, and the MMP inhibitors TIMP-1 and TIMP-2 in aseptic loosening of polyethylene prostheses, immunohistochemistry (IHC) and in situ hybridization (ISH) were performed on periprosthetic pseudosynovial interface tissues. Gelatinase A and MT1-MMP were strongly detected immunohistochemically in macrophages and multinucleated giant cells in contact with polyethylene wear debris. In contrast to MT1-MMP, gelatinase A mRNAs were not found in phagocytic cells but in surrounding fibroblasts, thereby suggesting cooperation between macrophages and fibroblasts in this process. While TIMP-1 was expressed essentially in hyperplastic pseudosynoviocytes as assessed by IHC and ISH, TIMP-2, MT1-MMP, and gelatinase A were colocalized in phagocytic cells. These data support the concept of progelatinase A activation involving a trimolecular complex (MT1-MMP-TIMP-2-gelatinase A) mechanism. Thus, this study demonstrated that gelatinase A and its activator might contribute to the aseptic loosening of polyethylene prostheses.

Adult↗

PubMed2006

Synergistic effects of mixed TiAlV and polyethylene wear particles on TNFalpha response in THP-1 macrophages.

TNFalpha is a potent osteoclastogenic cytokine that has a fundamental role in the pathogenesis of wear particle-induced osteolysis. Wear particles of one composition and their biological effects are well characterised. In contrast, little is known about the effects of mixed particles with respect to mix ratio and particle concentration. We evaluated the effects of different mix ratios of polyethylene and TiAlV particles on TNFalpha response. We used a human monocytic cell line (THP-1) in this in vitro study. THP-1 monocytes were differentiated to macrophage-like cells and exposed to different mixtures of lipopolysaccharide-detoxified polyethylene and TiAlV particles. TNFalpha was analysed in culture supernatants using ELISAs. Both polyethylene and TiAlV particles induced a dose- and time-related release of TNFalpha, with maximum levels after 6 h. A PE/TiAlV mix ratio of 36:1 at 10(8) particles/ml induced significantly higher TNFalpha concentrations compared to equal particle concentrations of isolated TiAlV (p=0.047) or PE (p=0.044), indicating the synergistic effect of mixed particles. These results provide evidence that TiAlV and polyethylene particles have significant synergistic effects, depending on the mix ratio and particle concentrations. This supra-additive effect can contribute substantially to the pathogenesis of implant particle-induced osteolysis.

Alloys↗

PubMed2001

Initial stability of modular acetabular components. Comparative in-vitro study with polyethylene and ceramic liners.

Modular acetabular components with alumina ceramic liners are currently used in total hip arthroplasty, but concerns have emerged regarding their high stiffness, which could cause impairment of stability, stress-shielding phenomena, and loosening. The purpose of the present biomechanical investigation was to compare the in-vitro initial stability of a modular press-fit acetabular component using a polyethylene liner and using an alumina liner. The initial stability was investigated by measuring the micromotion between the implant and the acetabulum during the application of physiological load (2.39 kN). The micromotion of the acetabular component was investigated in 10 acetabuli using a polyethylene liner and in 10 acetabuli using an alumina liner. Micromotion was assessed at the level of the Os ilium, Os pubis, and Os ischium using 3 electromagnetic transducers. The transducers have a sensitivity of 1 micron and a range of measurement of 500 microns. All implants have been fixed on human pelves made of polyurethane. Measurement of implant micromotion showed stable conditions at the level of the three main sectors of the acetabulum during all tests. No statistically significant differences of results were observed between the group of specimens with polyethylene liner and the group of specimens with alumina liner. The mean micromotion values of the uncemented cups were similar to the mean micromotion values of 10 cemented cups investigated to achieve comparative data of stability. In conclusion, the modular acetabular components inserted using an alumina liner showed a satisfactory initial stability in-vitro. The results do not contrast with those achieved using the same cup inserted with a polyethylene liner.

Acetabulum↗

PubMed1996

Analysis of lymph nodes for polyethylene particles in patients who have had a primary joint replacement.

Polarized light microscopy has been used for more than forty years to identify polyethylene particles in histological specimens; however, few investigators have assessed the specificity of this technique. We examined specimens from dissected lymph nodes for the presence of strongly birefringent particles resembling polyethylene. Twenty-seven patients had dissection of lymph nodes after a total joint replacement (Group 1), and a control group of eighteen patients had dissection of lymph nodes before a total joint replacement (Group 2). Specimens from both groups of lymph nodes were examined under plain and polarized light. The presence of strongly birefringent particulate debris was graded from 0 to 4. Twenty-one (78 per cent) of the twenty-seven patients in Group 1 and eight of the eighteen patients in Group 2 had strongly birefringent particles in the lymph nodes. Our results demonstrate that, in the assessment of the systemic dissemination of polyethylene in the lymphoreticular system, polarized light microscopy has important limitations. More refined techniques employing polarized light and other methods of physical and chemical analysis may be necessary to identify polyethylene particles accurately within the lymphoreticular system and periprosthetic tissue.

Adult↗

PubMed1997

Measurement of polyethylene wear in acetabular components inserted with and without cement. A randomized trial.

We measured the three-dimensional wear of polyethylene after total hip arthroplasty with a titanium metal-backed Mallory-Head prosthesis that was inserted with cement in sixty-nine patients (sixty-nine hips) and with a press-fit titanium metal-backed Mallory-Head prosthesis that was inserted without cement in seventy patients (seventy hips). A modular titanium femoral head was used in all of the hips. The patients in the present study were part of a larger double-blind randomized trial comparing the result of total hip arthroplasty performed with cement with that of the same procedure performed without cement in 250 patients. The criterion for inclusion in the study of polyethylene wear was a minimum duration of follow-up of four years, which was met by 148 patients. As adequate radiographs for digitization were not available for nine patients, 139 patients were included in the present study. The age of the patient, the postoperative Harris hip score, the diameter of the femoral head, the thickness of the liner in the polar region of the acetabular component, and the duration of follow-up were similar for the two groups. The mean rate of volumetric wear of the polyethylene was significantly greater in the prostheses that had been inserted without cement than in those that had been inserted with cement (155.1 cubic millimeters per year compared with 98.5 cubic millimeters per year; p = 0.000008). Thirty-four (49 per cent) of the seventy hips in which the prosthesis had been inserted without cement had evidence of osteolysis on radiographs, compared with twelve (17 per cent) of the sixty-nine hips in the other group (p = 0.0002). Osteolysis was associated with an increased rate of polyethylene wear only in the hips in which the prosthesis had been inserted without cement.

Acetabulum↗

PubMed1997

Radiographic evaluation of penetration by the femoral head into the polyethylene liner over time.

UNLABELLED: We examined the pattern of temporal penetration by thirty-two-millimeter-diameter femoral heads into polyethylene liners in a group of 105 hips (103 patients) in which an Arthropor metal-backed cup had been implanted. Each patient was evaluated radiographically and clinically at a minimum of four different postoperative intervals. The initial evaluation was performed a mean of 2.9 weeks (range, one to fifteen weeks) postoperatively, and the latest evaluation was performed a mean of 7.9 years (range, five to ten years) postoperatively. Two-dimensional wear - that is, penetration by the femoral head into the ultra-high molecular weight polyethylene liner - was determined from anteroposterior radiographs of the pelvis with a computer analysis system that calculated the change in the position of the center of the head relative to the center of the cup. Three new findings are reported. First, there was a large difference (mean, 1.1 millimeters) between the center of the head and that of the cup as measured on the initial postoperative radiographs. This difference underscores the need for researchers to consider the initial displacement of the head when measuring and reporting polyethylene wear. Second, although there was wide variation in responses among individuals, temporal examination of the data revealed a trend toward a decreasing rate of penetration with time. Moreover, the rate of penetration appeared to reach a steady-state value after the sixth postoperative year and remained nearly constant until the ninth postoperative year. Third, by comparing the subsets of patients who had the greatest and the least initial penetration by the head, we found that penetration behavior, although remarkably different between the groups in the first three years postoperatively, became similar with time. CLINICAL RELEVANCE: When making decisions regarding individual patients or hip systems that demonstrate penetration by the femoral head into the polyethylene liner, clinicians should consider the patterns of penetration over time. Measurements of the amount and rate of penetration that are based solely on the most recent radiograph do not represent the full clinical picture. We advocate more frequent radiographic follow-up and, when available, analysis of serial radiographs for patients who have excessive penetration by the femoral head into the acetabular liner.

Adult↗