1,720,977 research outputs found
A family of Azumaya algebras arising from quantum groups
No full textWe present a family of Azumaya algebras. These algebras arise from the representation theory of a multiparameter quantum deformation of the coordinate ring of an algebraic group G at roots of 1. The spectra of these algebras are Galois coverings of minimal T-biinvariant Poisson submanifolds of G, for the Poisson structure
given by
the
quantization
Quantum double and multiparameter quantum groups
No full textAfter Drinfel'd and Jimbo's construction of quantized universal enveloping algebra associated to each complex simple Lie algebra, larger classes of quasitriangular Hopf algebras as been found and studied. We prove that the multiparameter quantum groups defined by Reshetikhin and De Concini-Kac-Procesi are indeed equivalent. Besides we write this algebra as the quantum double of a Borel-type sub-Hopf-algebra
Heterophilic antibody interference in a non-endogenous molecule assay: an apparent elevation in the tacrolimus concentration.
No full textBACKGROUND:
In drug monitoring assays the most common interferences are due to hematocrit, other drugs or their metabolites, while the interference by heterophilic antibodies has been reported only when measuring endogenous molecules. In the present paper a heterophilic antibody interference in the tacrolimus measurement is described.
METHODS:
Samples from a patient treated with tacrolimus were analyzed on RxL Dimension analyzer. Ranging drug concentrations from 49 to 12.5 microg/L, even after the interruption of the treatment, confirmation analysis were performed using heterophilic blocking tubes before tacrolimus measurement on the same analyzer, then testing the samples on V-Twin System, finally incubating the samples with chlorophenol red beta-d-galactopyranoside, beta-galactosidase, polyclonal mouse IgG, protein A and Protein G resin.
RESULTS:
The elevated tacrolimus concentrations were due to the presence of an interference attributable to heterophilic antibodies, as confirmed by treating the samples with heterophilic blocking tubes and protein G resin.
CONCLUSIONS:
a) The interference caused by heterophilic antibodies can be found not only in immunoassays measuring endogenous molecules, but also in those for exogenous molecules; b) the pre-treatment sample procedure, which represent the main difference between the methods affected and unaffected by the interference, is a fundamental step in removing the antibodies responsible of the interference
Evaluation of a new capillary zone electrophoresis system for the identification and typing of Bence Jones Protein
No full textObjectives: Capillary electrophoresis has recently emerged as a new sensitive technique for the separation of urinary proteins. We evaluated a new method for Bence Jones Protein (BJP) detection and characterization on native urine samples by the Paragon CZE (TM) 2000 system. To avoid interference in electrophoretic separation, urine samples were preliminarily treated for the selective removal of interfering salt particles.
Design and methods: The evaluation was done on a total of 350 fresh 24-h urine samples. The salt particle removal consisted of a manual chromatographic separation, optimized in the course of our evaluation. Capillary zone urinary protein electrophoresis (CZ-UPE) was compared with conventional high-resolution electrophoresis on an agarose gel, while capillary immunosubtraction (CZU-IFE) was compared with agarose gel immunofixation.
Results: After finding a consistent protein loss in eluates, the preanalytical treatment was optimized by changing sample dilution and eluate collection. The within- and between-run imprecision values for monoclonal peaks corresponding to BJP ranged from 0.4-12.2% to 3.3-6.3%, respectively. The detection limit for BJP, defined as the lowest measurable monoclonal peak on CZ-UPE, was 0.0012 g/L for kappa BJP and 0.0007 g/L for lambda BJP. CZ-UPE and CZU-IFE sensitivities were significantly lower in urine samples with a total protein level 100 mg/L (92% and 94%, respectively). Comparison between BJP measurements obtained from densitometric scanning with those from absorbance tracing showed a correlation coefficient of 0.994 and a bias of 29.8 mg/L.
Conclusions: Paragon CZE (TM) 2000 can be introduced in routine for screening and typing of BJP; in urine samples with a total protein level > 100 mg/L, the performance is consistent with results from published validation studies on CZE applied to serum samples. (c) 2005 The Canadian Society of Clinical Chemists. All rights reserved
Quantitative automated particle-enhanced immunonephelometric assay for the routinary measurement of human cystatin C.
No full textHuman cystatin C is a low molecular mass protein of 13359 Dalton recently proposed as a new very sensitive marker of changes in glomerular filtration rate. Serum cystatin C concentration correlates negatively with glomerular filtration rate as well as or better than creatinine. We evaluated a recently introduced automated nephelometric immunoassay for cystatin C in serum or EDTA-plasma samples on the Behring Nephelometer System. The assay consists of incubating the 100-fold diluted sample for 6 minutes with latex particles covalently coated with anti-human cystatin C antibodies, and then quantifying the change of light-scatter produced. Method reproducibility is satisfactory, the intra- and inter-assay coefficients of variation ranging from 1.58% to 3.77% and from 5.6% to 11.47% respectively. Rheumatoid factor (< or = 1116 IU/ml), bilirubin (< or = 418 micrommol/l), triglycerides (10.47 mmol/), and haemoglobin (12 g/l) do not significantly interfere in the assay. No significant difference was found in cystatin C concentration between serum and EDTA-plasma samples. Cystatin C is stable in serum samples stored under different conditions up to one month. This method correlates well (mean difference=-0.536+/-0.307 mg/l) with another commercially available particle-enhanced turbidimetric immunoassay. Cystatin C offers better clinical sensitivity than creatinine for discriminating patients with normal renal function and those with mild-to-moderate reduction in renal function. This method is suitable for routine cystatin C measurement, including emergencies
An expert system for the classification of serum protein electrophoresis patterns
Full text linkBACKGROUND:
With the improvement of capillary electrophoresis, much progress has been made in terms of sensitivity and automation, but the interpretation of the patterns, actually, depends totally on expert personnel. The aim of this work was to evaluate Neurosoft-Sebia, an expert system developed to discriminate between regular and anomalous serum protein electrophoresis patterns performed on Capillarys2.
METHODS:
Neurosoft-Sebia, based on six auto-associative neural networks, was trained to create the initial knowledge base. In the tuning phase, 3000 electrophoretic patterns were performed in three different laboratories, and the discordances between human experts and Neurosoft-Sebia classifications were added to the initial knowledge base. Finally, the performances of Neurosoft-Sebia were evaluated using a benchmark dataset.
RESULTS:
The initial knowledge base was created with 2685 fractions. In the tuning phase, 241 discordances were found: 56 as regular by Neurosoft-Sebia and anomalous by human experts, and 185 as anomalous by Neurosoft-Sebia and regular by human experts. Sensitivity values were evidenced as the ability of Neurosoft-Sebia in selecting anomalous fractions, with an increase from 66.67% using the initial knowledge base to 97.40% using the enriched knowledge base.
CONCLUSIONS:
This work demonstrated how the ability of Neurosoft-Sebia in selecting anomalous pattern was comparable to that of human experts, saving time and providing rapid and standardized interpretations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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