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PubMed1980

Comparison of polyethylene glycol and polyoxyethylene stearate as excipients for solid dispersion systems of griseofulvin and tolbutamide I: phase equilibria.

Phase equilibrium diagrams were constructed based on hot-stage microscopy and differential scanning calorimetry of solid dispersions of griseofulvin or tolbutamide in polyethylene glycol 2000 or polyoxyethylene 40 stearate. The solid dispersions were prepared by physical mixing, fusion, and coprecipitation from ethanol. The phase diagrams were largely independent of the method of preparation of the dispersion systems. The diagrams were of the monotectic type for polyethylene glycol 2000 with each drug and for griseofulvin with each excipient, with the monotectic species being the pure drug. Polyoxyethylene 40 stearate with tolbutamide gave eutectic systems in which liquid polyoxyethylene 40 stearate dissolved up to 20% of the tolbutamide. The phase diagrams showed greater solubility of tolbutamide in liquid polyoxyethylene 40 stearate than in polyethylene glycol 2000 but showed a similar solubility of griseofulvin in each experiment. Solid solution formation was not detected.

Excipients↗

PubMed1982

Relative bioavailability of chlorthalidone in humans: adverse influence of polyethylene glycol.

The bioavailability of two commercial preparations of chlorthalidone was studied in healthy male subjects. Reference solutions/suspensions for the two products were chlorthalidone dissolved in a solution of water-polyethylene glycol and a solution/suspension of chlorthalidone. Bioavailability of the chlorthalidone in water-polyethylene glycol solution was significantly reduced in comparison to one of the commercial preparations, and trends in the data suggested that it was less well absorbed than either the chlorthalidone in water solution/suspension or the other commercial preparation of chlorthalidone. These data, together with previous reports indicating that polyethylene glycol may retard the absorption of some drugs in vitro, suggest that this compound should not be used to aid dissolution of drug in a reference standard for bioavailability investigations.

Adult↗

PubMed1986

Effect of polyethylene glycol 400 on the penetration of drugs through human cadaver skin in vitro.

The effect of polyethylene glycol 400 on the penetration of drugs through human cadaver skin is reported. Polyethylene glycol 400 was used in various concentrations in the donor and the receptor compartments. It was observed that polyethylene glycol 400 had significant effects on the penetration rates of compounds, both when used in the donor as well as in the receptor solutions. These effects were barrier specific and are related to the alteration of the skin structure and the mass flow of water.

Anti-Inflammatory Agents↗

PubMed2002

Dye injection for predicting pesticide movement in micro-irrigated polyethylene film mulch beds.

A new method is described for tracing water movement in polyethylene film covered soil beds. Dye was delivered via a drip tape micro-irrigation system which was placed in the bed as the soil beds were shaped and covered with polyethylene film. The dye was injected into the system and irrigated with water for 4-24 h at 0.41-1.38 bar (41-138 kPa) pressure depending on the experiment. The dye appeared as blue circles on the soil surface within 20 min of injection and produced a three-dimensional pattern in the soil profile. Injection-irrigation-pressure scenarios were evaluated by measuring dye movement directly below and between emitters by sliding fabricated blades vertically into the bed at the desired examination point and excavating the soil away from the blade. The dye typically produced a U shape on the face of the bed and the area was calculated for each of these exposed faces. The area increased as the length of irrigation and water pressure increased. Interrupted irrigation (pulsing) scenarios did not alter the calculated areas encompassed by the dye compared to uninterrupted irrigation scenarios. The blue dye provided a direct, inexpensive and easy method of visualizing water movement in soil beds. This information will be used to optimize application of emulsifiable plant-care products in polyethylene film mulch beds.

Coloring Agents↗

PubMed1999

Conjugation of polyethylene glycol via a disulfide bond confers water solubility upon a peptide model of a protein transmembrane segment.

The aqueous insolubility of hydrophobic peptides has presented a barrier to the structural characterization of membrane protein transmembrane domains. Since the conjugation of polyethylene glycol is known to modulate the solubility of certain proteins and peptides, we have prepared PEG-a-Cys reagent, a polyethylene glycol derivative which reacts spontaneously with Cys residues to attach polyethylene glycol to polypeptides via a mixed disulfide bond. When desired, the PEG moiety can be readily removed by reduction with tricarboxyethylphosphine. The aqueous solubilizing power of PEG-a-Cys reagent is confirmed with a synthetic hydrophobic peptide model of a generic transmembrane segment-soluble carrier fusion protein.

Amino Acid Sequence↗

PubMed1996

Uptake of organochlorine pesticides by solvent-filled cellulose and polyethylene membranes.

Membrane-based passive samplers were used to study the uptake of organochlorine pesticides (lindane, aldrin, dieldrin, and chlorpyriphos) in a continuous-flow system. The membranes were filled with cyclohexane and a mixture of cyclohexane and triolein. Uptake of the chemicals was 24-84 times faster in polyethylene membranes compared to that in cellulose membranes. This is a clear indication that polar cellulose membrane hinders the transport of lipophilic compounds. Though uptake rates in polyethylene membranes were much higher, they were unable to retain the receiving solvent for longer time periods. The diffusion rate of chemicals through polyethylene membranes was dependent not only on their lipophilicity but their molecular mass as well.

Cellulose↗

PubMed1982

Cementless fixation of polyethylene acetabular component in total hip arthroplasty.

A new concept of cementless fixation of a polyethylene acetabular component for total hip arthroplasty is presented. The spherical cup is fixed directly to the subchondral bone of the acetabulum by means of two pegs and screws. The polyethylene in direct contact to the bone adjusts to the deformation of the pelvis (Isoelasticity). Bone grows into the indentations of the outer surface of the implant. The elastic cup does not interfere with the physiological stress patterns of the hip joint so that a stable "biomechanical incorporation" of the implant is achieved. A follow-up of the first 250 cementless fixed polyethylene cups with an observation period of six months to four years with an average of 19 months is reported. So far no aseptic loosening of the implant has occurred.

Acetabulum↗

PubMed1994

Bisacodyl reduces the volume of polyethylene glycol solution required for bowel preparation.

PURPOSE: This study was designed to compare the efficacy and patient tolerance of standard orthograde bowel preparation using 4 liters of polyethylene glycol solution with only 2 liters of polyethylene glycol preceded by the stimulant laxative bisacodyl. METHODS: Three hundred eighty-two consecutive patients undergoing outpatient colonoscopy under two surgeons over a six-month period were randomized to receive one of the two preparations. Patients were asked to record the effects of the preparation and to give it a "discomfort rating" on a scale from 1 to 5. Surgeons were blinded to the preparation used and rated the quality of bowel cleansing on a scale of 1 to 5. One hundred ninety-one patients were randomized to the 4-liter preparation and 191 to the 2-liter preparation. RESULTS: Ninety-three percent of patients in the 2-liter group drank all of the solution as opposed to only 66 percent of patients in the 4-liter group. Patients in the 4-liter group gave the preparation significantly lower comfort scores than those in the 2-liter group (Fisher's exact test; P = 0.0001). The quality of bowel cleansing was not significantly different between the groups (P = 0.88). A total of 6.8 percent of the 2-liter group and 9.4 percent of the 4-liter group were considered by the surgeon to have had a poor preparation (rating 4 or 5). The quality of the preparation was found to correlate with the patients' age and compliance with the preparation regimen, and was found not to correlate with presenting symptoms, pathology, or a previous colonic resection. CONCLUSION: Bowel preparation with bisacodyl and 2 liters of polyethylene glycol is more acceptable to patients than a 4-liter regimen and is equally effective in cleansing the colon.

Adult↗

PubMed2001

Radiation technology in the preparation of polyethylene oxide hydrophilic gels and immobilization of proteases for use in medical practice.

This paper deals with the development of a technology for making a hydrophilic gel of polyethylene oxide reception in which radiating ability is employed to cause cross-linking of polymers in a water solution. The gel of polyethylene oxide was shown to be non-toxic, contain 5-50% of polymer and be useful in composite medicinal forms along with biologically active substances including Bac. subtilis proteases. Proteases immobilized in the gel possess high thermal stability and proteolytic activity and are readily applied in medicine. The effect of immobilized proteolytic and glucolytic enzymes of Bac. subtillis (Immozimase) on the warm ischemia-reperfusion (I/R) which can cause hepatic and jejunum injury was also studied. These enzymes were immobilized on water-soluble polymer polyethylene glycol by means of an electron beam. The number of degranulated mast cells as well as serum ALT after I/R in the group with Immozimase was decreased to almost half as compared with the control group. Pretreatment with Immozimase resulted in significant reduction of hepatic and gut neutrophil accumulation as compared with control animals. It was concluded that Immozimase has a protective effect for hepatic and gut ischemia/reperfusion, and this effect seems to be associated with prevention of leukocyte accumulation.

Bacillus subtilis↗

PubMed2006

Biofilm development of the polyethylene-degrading bacterium Rhodococcus ruber.

We have recently isolated a biofilm-producing strain (C208) of Rhodococcus ruber that degraded polyethylene at a rate of 0.86% per week (r2=0.98). Strain C208 adheres to polyethylene immediately upon exposure to the polyolefin. This initial biofilm differentiates (in a stepwise process that lasts about 20 h) into cell-aggregation-forming microcolonies. Further organization yields "mushroom-like" three-dimensional structures on the mature biofilm. The ratio between the population densities of the biofilm and the planktonic C208 cells after 10 days of incubation was about 60:1, indicating a high preference for the biofilm mode of growth. Analysis of extracellular polymeric substances (EPS) in the biofilm of C208 revealed that the polysaccharides level was up to 2.5 folds higher than that of the protein. The biofilm showed a high viability even after 60 days of incubation, apparently due to polyethylene biodegradation.

Biodegradation, Environmental↗

PubMed2005

Behavior of Hylamer polyethylene in hip arthroplasty: comparison of two gamma sterilization techniques.

Hylamer polyethylene was introduced in the 1990s as an alternative to conventional polyethylene. Its chemical and physical properties, and especially its high crystallinity, were claimed to improve resistance to wear. Initially Hylamer devices were sterilized by gamma radiation in air, then the technique was changed and gamma radiation was performed in the absence of oxygen. Clinical experience has shown the early loosening of some devices made from Hylamer. The aim of this study was to ascertain whether early wear and consequent osteolysis was linked to the sterilization method. We retrospectively compared 31 patients with hip prostheses with Hylamer liners sterilized by gamma radiation in air (group 1) with 30 patients with the same prosthesis, but sterilized in the absence of oxygen (group 2). The groups were similar for sex, age, disease, head diameter and material. Mean follow-up was 84 months and no clinical signs of failure were present. Radiographic measurement revealed that wear of group 1 was significantly greater than that of group 2 (0.23 mm/year vs 0.09 mm/year, p=0.001). Periacetabular and femoral osteolysis in group 1 was significantly greater than group 2. In conclusion, the method of sterilization might have influenced the outcome of Hylamer polyethylene liners.

Arthroplasty, Replacement, Hip↗

PubMed1997

Massive osteolysis induced by high molecular weight polyethylene wear debris.

We investigated the mechanism by which particulate wear debris of polyethylene may induce bone resorption using an in vivo model. Two uncemented total hip prostheses, in which the socket was directly in contact with acetabular bone, were selected because there was massive bone loss around the implant. A thick synovium-like layer was found at the polyethylene-bone interface during revision operations. Samples were examined by transmitted and polarised light microscopy, and by transmission electron microscopy. This study demonstrates that polyethylene wear products alone can cause massive osteolysis by triggering the formation of foreign body granuloma at the bone-implant interface.

Female↗

PubMedDate not supplied

Use of porous high-density polyethylene in revision rhinoplasty and in the platyrrhine nose.

Nasal reconstruction presents a significant challenge to the facial plastic surgeon. Reestablishment of the desired aesthetic nasal contour and restoration of respiratory function are the dual goals of this endeavor. While autologous cartilage or bone is considered optimal grafting material, the supply is often limited and harvesting entails additional morbidity. Many synthetic materials have been introduced for use in nasal reconstruction, but high infection and extrusion rates have left most surgeons dissatisfied with conventional implants. Porous polyethylene (Medpor) implants were used for nasal reconstruction in 187 patients; 66 (35.3%) patients underwent primary rhinoplasty, while revision surgery was performed in 121 (64.7%) patients. Most patients required multiple implants, including columella struts, plumper grafts, dorsal tip implants, and nasal valve battens. Postoperative follow-up ranged from 6 months to 3.5 years. Complications occurred in five (2.6%) patients. Three early and two delayed infections necessitated implant removal in five patients, all of whom had compromised skin-soft tissue envelopes secondary to heavy smoking, cocaine abuse, or prior surgery. One case of an overly augmented nasal dorsum and tip required implant removal, reduction, and reinsertion. All implants were easily removed. No other complications including implant extrusion or skin erosion have been noted. Porous polyethylene (Medpor) implants allow for fibrovascular ingrowth, which lends stability to the implant. Porous polyethylene implants are well tolerated and provide an ideal material for nasal reconstruction.

Humans↗

PubMed2006

Wear of crosslinked polyethylene under different tribological conditions.

Ultra high molecular weight polyethylene (UHMWPE) wear debris has been shown to be a major cause of long term failure of total joint replacements. Recently, crosslinking has been extensively introduced to reduce the wear of UHMWPE. In this study the wear of non-crosslinked and crosslinked UHMWPE were compared under a range of conditions. The materials examined were UHMWPE GUR 1050, non-crosslinked, moderately crosslinked--5MRad, and highly crosslinked--10MRad. The wear was examined on a multidirectional pin on plate rig. The effect of counterface roughness on wear under different kinematics was examined. The results from the different counterface conditions showed that highly crosslinked UHMWPE had significantly lower wear against both smooth and scratched counterfaces. However the reduction in wear for crosslinked polyethylene was less for scratched counterfaces. The second part of the study showed that all the UHMWPE's produced lower wear rates under lower multidirectionality because of reduced cross shear frictional forces and work. These findings are relevant to the consideration of the use of crosslinked polyethylene in the knee, where the kinematics have lower levels of cross shear and in the hip and knee against roughened metallic counterfaces.

Biomechanical Phenomena↗

PubMed1986

Acceleration of nucleic acid hybridization rate by polyethylene glycol.

The addition of polyethylene glycol to filter-bound nucleic acid hybridization greatly increases the hybridization rate. With single-stranded probes, the increase obtained with polyethylene glycol is significantly greater than that obtained with dextran sulfate. Additionally, polyethylene glycol is easier to manipulate and less expensive than dextran sulfate.

DNA, Bacterial↗

PubMed1987

Protein binding of palmitate measured by transmembrane diffusion through polyethylene.

Thin polyethylene membranes permit ready diffusion of protonated long-chain fatty acids but are impermeable to protein and ions. This circumstance recommends polyethylene for measuring the free fraction of fatty acids in the presence of a binding protein and for estimating the ionization constant with which to compute the equilibrium constant for the binding of fatty acid anions. As an example of this approach we report the binding of tracer palmitate to bovine albumin and bovine beta-lactoglobulin. We find a binding constant for the high-affinity site on albumin that is close to that calculated by others from heptane:H2O partition ratios. Our procedure is simpler, however, and free of the theoretical objection that heptane may alter the binding characteristics of the protein. Our estimate of the pKa for palmitic acid is 4.9, a finding that conforms to the widely predicted but heretofore unconfirmed expectation that long-chain fatty acids should have a pKa of about 4.8. Unidirectional flux measurements exclude direct exchange of palmitate between albumin and polyethylene.

Albumins↗

PubMed1987

Polyethylene-based high-performance liquid chromatography of chloroplast pigments: resolution of mono- and divinyl chlorophyllides and other pigment mixtures.

In addition to most chlorophylls and their derivatives, monovinyl and divinyl chlorophyll species were separated by high-performance liquid chromatography, using a polyethylene column and a simple elution with aqueous acetone. Peak retention and resolution of the pigment separation were greatly increased by increasing the polarity of the mobile phase and also by decreasing the column temperature. Polyethylene chromatography showed chlorophyll separation behavior similar to that of the octadecyl silica column, but it showed no adsorption of the pigment species containing free carboxylic acid groups, enabling the complete separation of chlorophylls and their derivatives. Polyethylene is a superior alternative stationary phase to the known reversed-phase materials for chlorophyll separation and analysis.

Acetone↗

PubMed1979

Preparation and properties of polyethylene glycol-trypsin adducts.

The covalent attachment of polyethylene glycol of 5000 daltons to non-essential groups on trypsin produces an adduct that no longer precipitates with anti-trypsin antibody. In comparison with trypsin, polyethylene glycol-trypsin preparations show equal or greater activity against N-alpha-benzoyl-L-arginine ethyl ester, about one-fourth activity against angiotensin II, and little activity against bovine liver catalase. The polyethylene glycol-trypsin adduct dissolves soft blood clots at one-fourth the rate of trypsin. Soybean trypsin inhibitor produces two-thirds inhibition of the adduct under conditions that cause complete inhibition of trypsin.

Angiotensin II↗