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A chromatographic method is described for 80% removal of polyethylene glycol of different types, 600-6000, from human immunoglobulin preparations. Bio-beads SM-2 were used in batch procedures or packed on a 16 x 100 mm column. The polyethylene glycols were desorbed with 75% ethanol.
The patellar component of a total knee replacement (TKR) is the most frequent source of non-septic complications after total knee arthroplasty. Fracture of patellar pegs in all polyethylene patellar components is a very rare occurrence. We report such a case of a patellar polyethylene fracture in a 72-year-old female patient 10 years after TKR. Due to patellar malalignment and high level of activity, the patellar components failed in this patient. This was treated arthroscopically by removing the components that failed and leaving the patella unresurfaced. We followed up the patient postoperatively and her symptoms were substantially resolved.
We report a case of dislocation of the polyethylene inlay in revision total knee arthroplasty. Eight days after revision arthroplasty due to a previous infection, the polyethylene inlay of a PCL- retaining cemented total knee arthroplasty dislocated at about 80 degrees of flexion on the CPM machine. Lateral X-ray examination revealed an anterior slope of the tibial cut of 5 degrees. Correction of the tibial slope to a posterior tibial slope of 7 degrees reduced the forces on the posterior aspect of the inlay and no redislocation occurred. The mechanisms causing tibial inlays to dislocate in TKA are analyzed and discussed.
We report the case of a patient who showed clinical and radiological signs of massive polyethylene wear 3 years after total hip replacement. Arthroscopy was performed to assess the loosening of the acetabular cup. The procedure showed the polyethylene element to be broken into three pieces in the area corresponding to the upper border.
PURPOSE: To develop a new mathematical model for calculating the volumetric wear of polyethylene cups from known values of the radius of the prosthesis head, the extent of linear wear and the direction of linear wear determined from standard antero-posterior radiographs. METHOD: A new mathematical model was developed. The results of this new mathematical model were compared with the results obtained using the standard, frequently used mathematical model, which takes into consideration only the radius of the prosthesis head and the extent of linear wear of the polyethylene cups. The results of both mathematical models were further compared with the results obtained by direct measurement of volumetric wear using the fluid displacement method. RESULTS: Comparison of the mathematical models shows that the average volumetric wear calculated using the new mathematical model is 8.5% smaller than the average volumetric wear determined by the fluid displacement method, while the average volumetric wear calculated by standard mathematical model is 17.5% higher. The results of the new mathematical model are, thus, notably less biased than those of the standard one. CONCLUSION: In calculating the volumetric wear from antero-posterior radiographs, not only the radius of the prosthesis head and the extent of the linear wear but also the direction of the latter has to be considered.
Sixty consecutive patients (60 hips) were allocated in two matched-pair groups. Patients were matched for age, gender, body mass index, level of activity, and bone stock. Both groups received an uncemented total hip arthroplasty with a modular press-fit cup and an alumina femoral head. In the first group, an acetabular liner made of polyethylene was used; in the second group, an alumina liner. Both groups were followed for a minimum of 5 years. No hip required revision, and there was no radiographic evidence of aseptic loosening in either group. Mean Harris hip score was 94.7 (87.1-99) points in the polyethylene group and 93 (88.5-100) points in the alumina group.
This paper describes a technique of using Medpor porous high-density polyethylene implants for nasal reconstruction and chin augmentation. This biocompatible material has been used successfully during the last decade for various applications in the reconstruction of the facial skeleton. Among its most frequent uses are repair of the orbital floor and reconstruction of the burned ear, which became standard methods at many centers. Relatively little experience is, at present, on hand concerning the use of porous polyethylene in reconstruction of the nasal framework. Twenty-three consecutive, difficult nasal reconstructions were performed using this method since 1996. Patients were followed up for from 1 to 3 years (mean, 2 years). The results were durable and stable over the time. Eight patients had saddle nose deformity and 15 had catastrophe noses, mostly referrals, previously operated on from one to four times. My aesthetic goals were correction of the depressed nasal dorsum, creation of an acceptable nasal dorsum in the thick and/or twisted noses, and tip elevation. For nasal applications Medpor is available as a strut or sheet. Its body, once implanted, becomes rapidly vascularized and both soft tissue ingrowth and collagen deposition occur. This was confirmed by the microscopic investigation of biopsies. One patient of Vietnamese origin had an aesthetically pleasing result, but her family refused to accept her westernized nose. This gave me a unique opportunity to study the whole Medpor implant 6 months after implantation. There were two complications, one small implant exposure and one low-virulent infection involving the nasal tip. Following revision and antibiotic treatment, both patients healed without sequel. All reconstructions were successful in restoring nasal aesthetics and function. Four patients underwent chin augmentations with an uneventful clinical course.
PURPOSE: This study evaluated the usefulness of combined polyethylene glycol solution plus contrast medium bowel preparation (PEG-C preparation) followed by dual-contrast computed tomography enema (DCCTE) and conventional colonoscopy. The main purpose of these examinations is the preoperative staging of already known tumors. MATERIALS AND METHODS: One hundred patients with colorectal tumors were alternately allocated to either a polyethylene glycol solution preparation (PEG preparation) group (n=50) or a PEG-C preparation group (n=50) before undergoing conventional colonoscopy and computed tomographic (CT) colonography. After conventional colonoscopy, multidetector row CT scans were performed. Air images were reconstructed for both groups; contrast medium images were additionally reconstructed for the PEG-C preparation group. DCCTE images were a composite of air images and contrast medium images without use of dedicated electronic cleansing software. Quality scores (the presence or absence of blind spots of the colon) were compared between the two groups. RESULTS: Complete tumor images were obtained by DCCTE for all 50 (100%) lesions in the PEG-C preparation group, as compared with only nine of the 50 lesions (18%) in the PEG preparation group (air-contrast CT enema). The overall quality score in the PEG-C preparation group was significantly better than that in the PEG preparation group (P<0.0001). CONCLUSIONS: DCCTE showed the entire colon without blind spots in nearly all patients in the PEG-C preparation group because the areas under residual fluid were reconstructed as contrast medium images. DCCTE and conventional colonoscopy after PEG-C preparation are feasible and safe procedures that can be used for preoperative evaluation in patients with colorectal cancer.
Carbon fibre-reinforced polyethylene cups were inserted in total hip arthroplasties for both hips of a male patient. Ten years after the arthroplasty of the right hip, an intrapelvic cyst was observed. The cyst was connected to the inner acetabular wall. The endoprosthetic cup showed gross loosening with a marked osteolysis of the acetabulum. Revision arthroplasty with allograft bone and an uncemented endoprosthesis was successfully performed. The fibrotic tissue at the bone-cement interface showed numerous histiocytic cells with cytoplasmic infiltrates of carbon and polyethylene particles. The left hip was also later revised for loosening, but no cyst formation was observed on that side.
GOAL: Goal of this study was the assessment of the frequency of constipation in patients of palliative care medicine and the efficacy of the use of laxatives. METHODS: In a retrospective study the computerized data of 206 patients were analysed by descriptive statistics. RESULTS: Constipation occurred in 42.7% of patients. Constipation appeared in 34% of 159 patients, who were treated with morphine. There was no correlation to gastrointestinal tumors. Laxatives were given to 74.3% of patients. Laxative use was uncomplicated in 78.4%. For therapy of constipation combined administration of polyethylene glycol, sodium picosulphate and paraffin was most effective. CONCLUSION: In palliative care patients the use of polyethylene glycol is recommended for treating morphine-related-constipation.
A new method has been developed for automatic measurement of polyethylene linear modification using three-dimensional CT in total hip arthroplasty (THA) and bipolar hemiarthroplasty (BHP). We obtained a three-dimensional digital image of the metal components by widening the maximum window width, adjusting the proper cutoff threshold level, and removing the metal artifact. The centric coordinates of both the metal-backed cup and the femoral head were calculated from this image. Modification was defined as a change in distance between those two points from their original interval. Phantom studies of the accuracy and reproducibility of the method indicated that the average error ranged from 0.02 to 0.12 mm and the standard deviation ranged from 0.01 to 0.05 mm. Clinical in vivo measurement was performed without error of computer software on 19 hips in which modification of highly cross-linked polyethylene components was significantly large.
Aseptic loosening is the major problem associated with joint arthroplasty, but little is known about the precise mechanism of osteolysis. To elucidate this mechanism we analyzed polyethylene particles retrieved from granulation tissue around the stem of loosened hip arthroplasties. Granulation tissue was obtained from 35 patients at revision surgery for a loosened hip and digested with papain, followed by ultracentrifugation. The isolated particles were identified with ultra-high molecular weight polyethylene particles by Fourier transform infrared spectroscopy. The morphology and number of particles were analyzed by scanning electron microscopy. Most of the particles were granular, with 87.9% being less than 1 microm in equivalent circle diameter (mean 0.83 +/- 0.45 microm). The mean number of particles per gram of tissue was 1.48 x 10(9) (range 7.59 x 10(7) to 1.15 x 10(10)). We compared these data to the radiological appearance and found that focal-type osteolysis contained more particles than the linear type. The amount of submicron-sized particles is related to the development of osteolysis.
Between 1971 and 1978, 62 patients underwent total hip replacements (THRs) with high-dose (100 Mrad) gamma-irradiated polyethylene sockets. After a mean follow-up of 17. 3 years (range, 6-23 years), 28 hips in 26 patients were available for radiographic wear measurement. Twenty-three THRs with non-irradiated sockets were used as controls, although all these hips had loosened within 13 years. The rate of linear wear in irradiated sockets was significantly lower throughout the follow-up period (less than 2 years, 0.16 and 0. 38 mm/year; 2-6 years, 0.05 and 0.29 mm/year; more than 6 years, 0. 05 and 0.28 mm/year, respectively; mean, P < 0.0001). This result has demonstrated that high-dose gamma-irradiated, cross-linked polyethylene is a promising articulating material for THRs.
In order to transport and cryopreserve human tissues, it is essential to have an easy-to-use recipient where tissues can be kept in sterile conditions. Here we show the results obtained by using Macopharma's tissue freezing bags, an aluminium-polyethylene multilayer bag, in our tissue bank of the Centro Comunitario de Sangre y Tejidos de Asturias. Five hundred and twenty-seven cancellous bone homografts were obtained from hospitals located 120 km around our Bank. The homografts were submitted to bacteriological controls and sent to our bank in these bags. They were stored at -70 degrees C and sent in dry ice to about 50 hospitals, where the tissue was bacteriologically controlled and grafted. Furthermore, the behaviour of these bags at -140 degrees C (vapour nitrogen) or -196 degrees C (liquid nitrogen) was tested. Our results indicate that Macopharma aluminium-polyethylene bags are suitable for the transporting and cryopreserving of cancellous bone homografts. These bags could also be used for keeping tissues in nitrogen containers.
A rapid, reproducible immune complex screening assay was used to quantitate levels of circulating immune complexes in the sera of normal subjects, patients with documented increases in immune complexes from rheumatoid arthritis, patients with clinically or microbiologically documented infections, and patients with cancer. Although wide variations in individual values within the groups were noted and the concurrent elevation of polyethylene glycol-circulating immune complex levels by infection was documented as expected, significant differences were found in the values in patients with cancer compared with those in normal subjects. The overall clinical application of polyethylene glycol-circulating immune complex screening is discussed and current application of screening of serial sera samples from individual patients for correlation with measurable tumor volume is proposed.
Larger elution volumes of proteins in gel filtration in the presence of polyethylene glycol than in its absence were explained in terms of the unfavorable interactions between polyethylene glycol and both the proteins and the gel matrix. This should favor the protein molecules being in the cavity of the gel matrix, leading to their slower elution, since, in this situation, the unfavorable interactions are decreased.
A radioassay for determining biotinidase activity in human serum was developed, using N-[beta-(4-OH-3-125I-phenyl)ethyl]-biotinamide in combination with biocytin as the substrate, avidin as a binding protein, and polyethylene glycol as a separation reagent. The gamma-emitting 125I-biotinamide (= tracer) was synthesized by coupling (pH 8.5, 20-22 degrees C, 90 min) N-hydroxysuccinimidobiotin to 125I-tyramine. Using polyethylene glycol as a separation reagent, it was possible to eliminate several problems that were encountered when other separation reagents were used. Biotinidase activity was evaluated following the cleavage of the 125I-biotinamide and expressed in fmol of tracer cleaved.min-1.ml-1 in the presence of 9 nmol of biocytin. Under the conditions used, the time response of the assay was linear up to 3 h. The method is simple to perform, more sensitive than the previously described methods, and reproducible (intra- and interassay CVs of 4.9 and 10.2%, respectively) and allows the simultaneous handling of more than 100 samples in less than 3 h.
This article describes a general method for detecting pegylated proteins directly after SDS-PAGE. The proteins to which polyethylene glycol (PEG) molecules are attached are stained with a barium iodide solution. The staining is based on the formation of a barium iodide complex with PEG. The described method combines a specific staining of PEG molecules with the high resolution of the SDS-PAGE method. It is shown that pegylated protein is detectable on SDS-PAGE as well as on IEF at concentrations that are not detectable by Coomassie protein staining. This paper also describes the determination of the molecular weight of pegylated hirudin by calibrating SDS-PAGE with polyethylene glycol of different molecular weight. Under the conditions used, PEG showed linear mobility during electrophoresis. However, the use of nonpegylated proteins as standards resulted in incorrect molecular weight values due to the lower mobility of the pegylated protein during electrophoresis. The method described might reflect a general method for determining molecular weight of pegylated proteins.