Anatomical and/or pathological predictors for the “incorrect” classification of red dot markers on wrist radiographs taken following trauma

OBJECTIVE: To establish the prevalence of red dot markers in a sample of wrist radiographs and to identify any anatomical and/or pathological characteristics that predict “incorrect” red dot classification. METHODS: Accident and emergency (A&E) wrist cases from a digital imaging and communications in medicine/digital teaching library were examined for red dot prevalence and for the presence of several anatomical and pathological features. Binary logistic regression analyses were run to establish if any of these features were predictors of incorrect red dot classification. RESULTS: 398 cases were analysed. Red dot was “incorrectly” classified in 8.5% of cases; 6.3% were “false negatives” (“FNs”)and 2.3% false positives (FPs) (one decimal place). Old fractures [odds ratio (OR), 5.070 (1.256–20.471)] and reported degenerative change [OR, 9.870 (2.300–42.359)] were found to predict FPs. Frykman V [OR, 9.500 (1.954–46.179)], Frykman VI [OR, 6.333 (1.205–33.283)] and non-Frykman positive abnormalities [OR, 4.597 (1.264–16.711)] predict “FNs”. Old fractures and Frykman VI were predictive of error at 90% confidence interval (CI); the rest at 95% CI. CONCLUSION: The five predictors of incorrect red dot classification may inform the image interpretation training of radiographers and other professionals to reduce diagnostic error. Verification with larger samples would reinforce these findings. ADVANCES IN KNOWLEDGE: All healthcare providers strive to eradicate diagnostic error. By examining specific anatomical and pathological predictors on radiographs for such error, as well as extrinsic factors that may affect reporting accuracy, image interpretation training can focus on these “problem” areas and influence which radiographic abnormality detection schemes are appropriate to implement in A&E departments

Fluorescent detection of DNA single nucleotide polymorphism by electric field assisted hybridization/melting of surface-immobilized oligonucleotides

Deoxyribonucleic acid (DNA) self-assembled monolayers (SAMs) immobilized on gold electrodes are the basis of many electrochemical biosensors. Control of the interfacial behavior of DNA by means of an electric field is of interest for sensing applications such as the detection of single nucleotide polymorphisms (SNPs). Moreover, the in situ characterization of immobilized DNA monolayers at a molecular level is important for the fabrication of robust, reliable and sensitive sensors. The thesis aims at studying the discrimination between DNA strands containing SNPs on the basis of electric-field assisted hybridization/denaturation of DNA. In situ electrochemical fluorescence microscopy is used as a detection methodology and characterization tool for DNA interfaces. For this purpose, fluorescently labeled DNA sequences are immobilized at gold electrodes as thiol SAMs. First, the SAMs under investigation were composed of perfect match or SNP-containing target sequences. The relationship between the applied potential and the denaturation of DNA duplexes was investigated. Electrochemical melting was observed at -0.25 V vs. Ag|AgCl and attributed to an electrostatics-based melting mechanism. A model based on electrical double layer theories was proposed to explain the observed partial electrochemical melting. The influence of various parameters was systematically investigated such as the assembly of the SAM and the measurement conditions. The observed trends were attributed to a destabilization of the duplex. The most influential variables were the DNA sequence (e.g. mismatch near the electrode surface), ionic strength and temperature. Next, a FRET methodology was investigated by studying a model DNA SAM system labeled with a FRET pair. The aim of the study was to gain information regarding the local molecular scale environment of a DNA SAM under measurement conditions. The influence of surface crystallography on the SAM organization was studied by wide-field FRET microscopy. FRET measurements were used in a semi quantitative way to characterize the uniformity of the DNA monolayer. A departure from the ideal uniform DNA distribution was observed for the (111) and (110) surface regions. The study provided a proof of concept for the use of electrochemical FRET microscopy as an in situ characterization tool for DNA modified electrode surfaces.Science, Faculty ofChemistry, Department ofGraduat

Fluorescent detection of DNA single nucleotide polymorphism by electric field assisted hybridization/melting of surface-immobilized oligonucleotides

RésuméLes monocouches auto-assemblées d'ADN immobilisées sur électrodes d'or sont à la base de nombreux biocapteurs électrochimiques. Le contrôle du comportement interfacial de l'ADN par le biais d'un champ électrique est intéressant pour la détection de polymorphisme nucléotidique simple (PNS). La caractérisation in situ de monocouches d'ADN à l'échelle moléculaire est importante pour la fabrication de biocapteurs robustes, fiables et sensibles.La thèse porte sur la détection du PNS dans l'ADN par le biais d'hybridation/dénaturation induite par le champ électrique. La microscopie de fluorescence sous conditions électrochimiques est utilisée comme méthodologie de détection et outil de caractérisation de l'interface d'ADN. À cette fin, des séquences d'ADN marquées par des sondes fluorescentes sont immobilisées sur des électrodes d'or sous forme de monocouches auto-assemblées (SAM) thiolées.Premièrement, les SAMs sont composées de séquences cibles présentant ou non une mutation ponctuelle. La relation entre le potentiel appliqué et la dénaturation du double brin est étudiée. La dénaturation électrochimique est observée à -0,25 V vs AgDeoxyribonucleic acid (DNA) self-assembled monolayers (SAMs) immobilized on gold electrodes are the basis of many electrochemical biosensors. Control of the interfacial behavior of DNA by means of an electric field is of interest for sensing applications such as the detection of single nucleotide polymorphisms (SNPs). Moreover, the in situ characterization of immobilized DNA monolayers at a molecular level is important for the fabrication of robust, reliable and sensitive sensors.The thesis aims at studying the discrimination between DNA strands containing SNPs on the basis of electric-field assisted hybridization/denaturation of DNA. In situ electrochemical fluorescence microscopy is used as a detection methodology and characterization tool for DNA interfaces. For this purpose, fluorescently labeled DNA sequences are immobilized at gold electrodes as thiol SAMs.First, the SAMs under investigation were composed of perfect match or SNP-containing target sequences. The relationship between the applied potential and the denaturation of DNA duplexes was investigated. Electrochemical melting was observed at -0.25 V vs. AgDoctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Application of FRET Microscopy to the Study of the Local Environment and Dynamics of DNA SAMs on Au Electrodes

Immobilized DNA probe strands self-assembled on an electrode surface are the bases of many electrochemically based biosensors. Control or measurement of the local environment around each DNA molecule tethered to the electrode surface is needed because the local environment can influence the binding or hybridization efficiency of the target in solution. Measurement of this local environment in buffer or under electrochemical control can be challenging. Here we demonstrate the use of fluorescence microscopy and a Förster resonance energy transfer (FRET) methodology to characterize multicomponent DNA SAMs. The DNA SAMs that were studied were composed of a series of mole fraction ratios of alkylthiol-modified DNA which was labeled with either AlexaFluor488 or AlexaFluor647, a FRET donor and acceptor, respectively. The DNA SAMs were hybridized before assembly onto the electrode surface. Wide-field filter-based FRET microscopy was used to study the assembly of DNA SAMs onto gold bead electrodes. These single-crystal gold bead electrodes contain many surface crystallographic regions which enable the comparison of the adsorbed DNA local environment. These surfaces show that most surface modifications are uniformly prepared, and the FRET efficiency can be explained through simple surface density considerations. The FRET efficiency for different compositions of the donor and acceptor for these regions is also explained through 2D FRET modeling. Not all surfaces were similar to the (111) and (110) regions showing deviations from the expected FRET behavior. Also demonstrated is FRET imaging using a confocal microscope. This approach proves useful in the analysis of a more dynamic system, such as the analysis of reductive desorption of the mixed-component DNA SAM. FRET microscopy is useful for surface analysis of the DNA local environment, enabling a measure of the surface modification, local density, and clustering and eventually a new detection modality.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Nonunion of a comminuted intra-articular wrist fracture after external fixation - A case report and review of the literature

Nonunion is a very rare complication of a comminuted intra-articular wrist fracture treated by external fixation. The authors describe the likely reasons and the after-care, in order to avoid this complication. © 1991 Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe