Electrochemical analysis of copper ion using a Gly-Gly-His tripeptide modified poly(3-thiopheneacetic acid) biosensor.

A novel biosensor harnessing a conducting polymer functionalized with a copper ion specific peptide proved to be highly effective for electrochemical analysis of copper ions. The developed sensor comprised a transducer based on a conducting polymer (poly(3-thiopheneacetic acid)) electrode and a probe (tripeptide, Gly-Gly-His) selectively cognitive of copper ions. For functionalization of the electrode, the carboxylic group of the polymer was covalently coupled with the amine group of the tripeptide, and its structural features were confirmed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection infrared (ATR-IR) spectroscopy. The peptide modified polythiophene biosensor was used for the electrochemical analysis of various trace metal ions by square wave voltammetry. The electrode was found to be highly sensitive and selective to Cu(2+) in the range of 0.02-20 microM with almost no cross binding to other metal ions such as Ni(2+) and Pb(2+). Furthermore, the developed sensor exhibited a high stability and reproducibility despite the repeated use of the sensor electrode and probe. With the advent of more diverse affinity bioprobes specific towards a broad range of analytes, the demonstrated strategy harnessing peptide modified polythiophene biosensor is likely to provide an excellent platform for the selective determination of trace amount of analytes whose detection is otherwise cumbersome.

The economics of inclusion body processing.

Many recombinant proteins are often over-expressed in host cells, such as Escherichia coli, and are found as insoluble and inactive protein aggregates known as inclusion bodies (IBs). Recently, a novel process for IB extraction and solubilisation, based on chemical extraction, has been reported. While this method has the potential to radically intensify traditional IB processing, the process economics of the new technique have yet to be reported. This study focuses on the evaluation of process economics for several IB processing schemes based on chemical extraction and/or traditional techniques. Simulations and economic analysis were conducted at various processing conditions using granulocyte macrophage-colony stimulating factor, expressed as IBs in E. coli, as a model protein. In most cases, IB processing schemes based on chemical extraction having a shorter downstream cascade demonstrated a competitive economic edge over the conventional route, validating the new process as an economically more viable alternative for IB processing.

Selective precipitation of DNA by spermine during the chemical extraction of insoluble cytoplasmic protein.

The direct chemical extraction of recombinant L1 protein (the major capsid protein of human papillomavirus type 16) from the cytoplasm of E. coli HMS174(DE3) has recently been demonstrated at high cell density (to OD(600) = 160) without the use of reducing agent (1). Coextraction of DNA at high concentration prevents direct coupling to postextraction recovery operations including expanded bed adsorption. In this study, spermine is used to selectively precipitate DNA during chemical extraction. Highly efficient and selective DNA precipitation was achieved. An approximate 10-fold increase in the specific spermine concentration (mg of spermine/mg of DNA) was required to precipitate DNA when 8 M urea was added to the extraction buffer. EDTA (3 mM), required for effective chemical extraction, does not significantly inhibit DNA precipitation. Precipitation selectivity was demonstrated in a bovine serum albumin spiking test, with almost complete recovery of the spiked protein. During studies on the direct extraction of L1 protein from cells at OD(600) = 80, high DNA removal efficiency (>85%) and negligible L1 protein coprecipitation were achieved. This selective precipitation technique simply requires the addition of spermine to the chemical extraction buffer and therefore does not increase technique complexity. This modification enhances the method's general applicability and enables direct coupling to downstream recovery units following chemical extraction at high cell and product concentrations.

Direct chemical extraction of a recombinant viral coat protein from Escherichia coli at high cell density.

The release of protein and DNA from nonrecombinant E. coli JM101 and recombinant E. coli HMS174(DE3) expressing L1 (the major viral coat protein of human papillomavirus type 16) as an inclusion body was demonstrated at high cell density (OD(600) = 160). For the nonrecombinant strain, extraction efficiency decreased significantly as cell mass increased, with a high viscosity increase in the postextraction broth. A different dependence on cell concentration was observed for the recombinant strain, with total protein extraction efficiency exceeding 85% for both uninduced and induced cells. Almost complete release of the recombinant L1 protein was achieved at high cell concentration (OD(600) = 80 approximately 160) without the use of reducing agent. This greatly extends the concentration range for chemical extraction.

Effect of polyethylene wear on osteolysis in cementless primary total hip arthroplasty: minimal 5-year follow-up study.

We measured polyethylene wear radiographically in 85 cementless primary total hip arthroplasties. All patients were followed up for at least 5 years (mean, 6.3 years). The mean extent of linear wear was 0.88 mm, and the mean rate of linear wear was 0.14 mm/y. The mean volumetric wear was 539.42 mm3, and the mean rate of volumetric wear was 87.69 mm3/y. Polyethylene wear was correlated inversely with the patients' age only and was not influenced by other clinical factors. Osteolysis developed in 34 femurs and in 11 acetabula. Radiographic loosening was found in 2 cases in the femur and none in the acetabulum. Polyethylene wear was significantly correlated with frequency and size of osteolytic lesions. Therefore, polyethylene wear was considered one of the major causes of osteolysis, but it was not directly associated with prosthesis loosening. To reduce the extent of polyethylene wear, the material characteristics of polyethylene should be improved, or more durable articulating materials should be developed.

Radiographic parameters of acetabulum for dysplasia in Korean adults.

We analyzed plain radiographs of 591 normal adult hips of various parameters to evaluate the radiological characteristics of the hip joint including the center-edge (CE) angle, acetabular angle, acetabular depth, acetabular roof obliquity and roof angle, and also to verify the rate of acetabular dysplasia. The CE angle was negatively correlated with acetabular angle and acetabular obliquity, but it was positively correlated with acetabular depth and roof angle. The rate of acetabular dysplasia (CE angle < 20 degrees) was 1.8%. We concluded that the CE angle and acetabular angle are more useful parameters for the diagnosis of acetabular dysplasia because there was no significant difference with advancing age and gender, as well as relatively small standard deviations.

Pathological mediopatellar plica found in the knee of an infant.

We report the case of a pathological mediopatellar plica found in the right knee of a 15-month-old infant girl. Flexion contracture of the knee was found to be 40 degrees. An arthroscopic view showed a large and thick voluminous mediopatellar plica. It was trapped between the patella and the medial femoral condyle and it was in tight contact with the medial facet of the patella at 40 degrees flexion in the knee, blocking further extension. A longitudinal groove was noted on the articular surface of the medial femoral condyle that looked as if it had another trochlea on arthroscopic view. The mediopatellar plica came into contact with the groove at 60 degrees flexion in the knee and it fitted precisely into the groove at further flexion. The pathological plica was resected arthroscopically, which resulted in approximately 10 degrees improvement in extension of the knee. Histological examination found hypertrophy and chronic nonspecific inflammation of the synovium. The patient was helped with range-of-motion exercise and quadriceps-strengthening exercise. At 27 months follow-up, the knee had gained full extension. This article reports that a pathological mediopatellar plica may develop in infants.

Late dissociation of the polyethylene liner from a modular acetabular metal shell after primary total hip arthroplasty--a report of five cases.

Modular designs of hip prostheses have become popular recently. Along with complications inherent in all hip arthroplasty systems, modular systems have the additional potential for dissociation of components. Five male patients underwent total hip arthroplasties, in which all of the acetabular components were Harris-Galante II porous acetabular cups. Many years after the operation, the polyethylene liners were dissociated without any previous trauma or dislocation of the femoral heads, these dissociations and dislodgements were managed with open reduction. This complication can be predicted from clinical symptoms and signs. Roentgenograms must be taken and carefully compared to previous roentgenograms. We postulated two causes for the dissociation. First, the polyethylene liner was not fixed securely within the acetabular metal shell at the time of operation. Second, the locking mechanism of the acetabular metal shell was not strong enough to firmly hold the polyethylene liner within the acetabular metal shell. It does warrant that certain precautions must be taken when implanting modular components. The locking mechanism of the harris-Galante II porous acetabular component is mechanically weak and fails easily, therefore its design must be improved in an attempt to prevent postoperative dissociation of the polyethylene liner.

Arthroscopic findings of the synovial plicae of the knee.

From June 1991 to March 1993, 400 knees in 363 patients were studied arthroscopically to clarify the arthroscopic anatomy of the plica and determine the classification of the plica. The various patterns of the synovial plicae were classified according to their shape and size from the arthroscopic view. Incidences of the synovial plica at the knees were: suprapatellar plica, 87.0%; mediopatellar plica, 72.0%; infrapatellar plica, 86.0%; and lateral patellar plica, 1.3%. There was no significant correlation in frequencies and distributions of patterns among the four groups of the plica, between men and women, with age, and between right and left. However the significant similarity in patterns of the right and left knees in the same persons was noted.

Pathological infrapatellar plica: a report of two cases and literature review.

In two cases of flexion contracture of knees, the vertical septum pattern of the infrapatellar plica was noted arthroscopically to be thickened, fibrotic, and to have lost its elasticity. The plicae were impinged to the intercondylar notch and trochlea at extension of the knees, blocking further extension. The pathological plicae were resected, followed by improvement in range of the knees. At 6 months postoperatively, the knees gained full extension. This is the first report showing that the infrapatellar plica caused a clinical symptom.