Elimination Of False Positives Research Articles

Application of Quantitative Real-Time PCR for Monitoring the Process of Enrichment of Clones on In Vitro Protein Selection

In vitro selection of proteins from cDNA libraries using display technologies, such as the in vitro virus method, is a powerful means for the discovery of novel protein interactions. After iterative screening, selected proteins are usually identified and evaluated by cloning and sequencing analysis. Previously we applied real-time PCR for evaluation of the sequences obtained on in vitro virus screening. Here, we have presented additional data regarding monitoring of the process of enrichment of selected clones in each round of selection and elimination of false positives by real-time PCR, and have also discussed the utility of the novel method. This approach should also be applicable to other display technologies.

Virtual elimination of false positives in blue-white colony screening.

Virtual elimination of false positives in blue-white colony screening.

Computerized detection of pulmonary nodules in chest radiographs based on morphological features and wavelet snake model

We have developed a new computer-aided diagnosis scheme for automated detection of lung nodules in digital chest radiographs based on a combination of morphological features and the wavelet snake. In our scheme, two processes were applied in parallel to reduce the false-positive detections after initial nodule candidates were selected. One process consisted of adaptive filtering for enhancement of nodules and suppression of normal lung structures, followed by extraction of conventional morphological features. The other process consisted of a novel approach for elimination of false positives called the edge-guided wavelet snake model. In the latter process, multiscale edges of the candidate nodules were extracted to yield parts of the nodule boundaries. A wavelet snake was then used for fitting of these multiscale edges for approximation of the true boundaries of nodules. A boundary feature called the weighted overlap between the snake and the multiscale edges was calculated and used for elimination of false positives. Finally, the weighted overlap and the morphological features were combined by use of an artificial neural network for efficient reduction of false positives. Our scheme was applied to a publicly available database of digital chest images for pulmonary nodules. Receiver operating characteristic analysis was employed for evaluation of the performance of each process in the scheme. The combined features yielded a large reduction of false positives, and thus achieved a high performance in discriminating between true and false positives. These results show that our new method, in particular the false-positive reduction method based on the wavelet snake, is effective in improving the performance of a computerized scheme for detection of pulmonary nodules in chest radiographs.

胸部X線写真における肺結節状陰影の形状特徴量分析による偽陽性陰影の除去

胸部X線写真における肺結節状陰影の形状特徴量分析による偽陽性陰影の除去

Elimination of false positives generated through PCR re-amplification of differential display cDNA.

Differential display (DD) is a powerful molecular tool that allows the identification and subsequent isolation of transcripts differentially expressed between biological samples, for example, between undifferentiated and differentiated cells, between different tissues or in one tissue at different stages of development. However, significantly high rates of apparent false positives have been reported using this technique. We suggest that the vast majority of false positives do not represent the originally selected transcript, but instead result from the re-amplification of cDNA species that co-migrate with the cDNA of interest in DD gels. Here we describe the use of a procedure to resolve co-migrating cDNAs and to purify the candidate of interest before cloning. The use of this modified technique resolves downstream problems encountered during DD experiments.

An effective elimination of false positives isolated from differential display of mRNAs.

A reverse Northern analysis that effectively eliminates the false positives isolated from differential display of mRNAs (DD) is demonstrated. Preparation of probe by one-step labeling in reverse transcription reaction is found to be more effective and specific as compared to the preparation of probe by random priming of reverse transcribed cDNA pool. Reverse Northern assay of DNA fragments isolated from DD prior to their cloning into plasmid, analysis of multiple fragments on single slot blot, and requirement of RNA only in small amounts as compared to conventional Northern makes the protocol quick, effective, and economic.

Analysis of common opiates and heroin metabolites in urine by high-performance liquid chromatography.

A separation of heroin, 6-monoacetylmorphine, codeine, pholcodine, dihydrocodeine and morphine using a 200 x 2 mm I.D., 3 microns silica column with dichloromethane-pentane-diethylamine-methanol mobile phase is described. Data on the determination of these compounds in a urine matrix based on this separation using a solid-phase pretreatment with Bond Elut Certify cartridges and nalorphine as an internal standard are shown. The compounds listed can be quantified at levels below that generally accepted as the cut-off level for the screening for opiates by enzyme immunoassay (EMIT) with detection limits for the different opiates ranging from 4 to 20 ng ml-1. Comparative data are shown of subject urine samples assayed for opiates by both the enzyme immunoassay and the proposed method. The utility of the method for the elimination of so-called false positives detected by EMIT due to the presence of medically prescribed and non-prescription opiates in urine is discussed.

A Combined Biological and Enzymatic Amplification (BIO-PCR) Technique to DetectPseudomonas syringaepv.phaseolicolain Bean Seed Extracts

A polymerase chain reaction (PCR) method, hereafter referred to as BIO-PCR, that combines biological and enzymatic amplification of PCR targets and simplified procedures for sample processing is described for the detection of Pseudomonas syringae pv. phaseolicola in bean seed extracts. Seeds are soaked overnight following standard protocols and aliquots of the extracts are plated onto a general agar medium. After 45-48 hr of incubation, the plates are washed with water to remove bacterial cells and aliquots of a pooled washing are subjected to two consecutive rounds of PCR, without prior DNA extraction, using «nested» pairs of primers designed to amplify a segment of the organism's tox (phaseolotoxin) gene region. Positive detection was reproducibly obtained at near-limit concentrations of the pathogen in the seed wash. Advantages of BIO-PCR over existing PCR techniques include the elimination of false positives resulting from the presence of dead cells that may be present in the seed, elimination of false negatives due to potential PCR inhibitors in seed extracts, increased sensitivity of detection, and no need for DNA extraction prior to amplification. Accordingly, BIO-PCR should prove useful for routine detection of other bacterial pathogens of quarantine importance. The primers detected some nontoxigenic strains of the pathogen, which evidently contain part of or the entire tox gene cluster

Context-based automated detection of epileptogenic sharp transients in the EEG: elimination of false positives

This paper describes a knowledge-based system for the elimination of false positives in the automated detection of epileptogenic sharp transients in the EEG. The system makes comprehensive use of spatial and temporal context information available on 16 channels of EEG, EKG, EMG, and EOG. A knowledge-based implementation is used because of the ease with which it allows the contextual rules to be expressed and refined. The resulting system is shown to be capable of rejecting a wide variety of artifacts commonly found in EEG recordings, artifacts that cause numerous false positive detections in systems making less comprehensive use of context.

Rapid large scale screening of blood donor plasma for IgA deficiency, confirmation and quantitation

Plasma from each of 20,068 blood donor samples collected for routine ABO and Rhesus grouping were screened for IgA deficiency using a rapid latex agglutination inhibition technique. 83 donors gave positive reactions with the latex screening reagent used. After elimination of the various false positives using further latex tests, 24 donors were eventually classified as true IgA deficients with an IgA level of less than 0.05 g/L, giving an incidence of 1:836.

A system for real time fluorescence imaging in color for tumor diagnosis

Early tumors can be diagnosed by the fluorescence of an injected, tumor-specific agent such as dihematoporphyrin ether. However, brightness or intensity contrast is low because of the autofluorescence of tissue. Addition of color (hue) information aids in detection of tumors, and in elimination of false positives. Standard color video cameras are not sensitive enough to image the weak fluorescence. Thus an intensified monochrome video camera has been equipped with a synchronized color filter wheel, and the image displayed by multiplexing alternate lines to a red green blue (RGB) monitor.

Elimination of labetalol-induced false positives in drug analyses.

Journal Article Elimination of labetalol-induced false positives in drug analyses. Get access A Wu, A Wu Search for other works by this author on: Oxford Academic Google Scholar D D Bretl, D D Bretl Search for other works by this author on: Oxford Academic Google Scholar M L Pearson, M L Pearson Search for other works by this author on: Oxford Academic Google Scholar G S Wolffe, G S Wolffe Search for other works by this author on: Oxford Academic Google Scholar M L Miller M L Miller Search for other works by this author on: Oxford Academic Google Scholar Clinical Chemistry, Volume 32, Issue 2, 1 February 1986, Page 407, https://doi.org/10.1093/clinchem/32.2.407 Published: 01 February 1986

Results of a Multicentre Clinical Trial of the Solid‐Phase Enzyme Immunoassay for Hepatitis B Surface Antigen

The results obtained in a multicentre clinical trial of an enzyme immunoassay (EIA) method for hepatitis B surface antigen (HBsAg) (65,451 sera tested) have demonstrated that this new test has a significantly higher sensitivity than a reversed haemagglutination test (rHA). In a part of the trial, EIA was also compared with radioimmunoassay (RIA). Only a small number of discrepant results was obtained with these two tests, indicating similar sensitivities. No definite conclusion about a difference in sensitivities could be drawn from these results. Although the specificity of the EIA screening test is lower than that of rHA and RIA, the mean percentage of false positives was 2.2% of the total number of donor samples screened. Presumptive positives in EIA were subjected to a confirmatory test based on neutralization with human antibodies to HBsAg. After elimination of false positives in EIA screening, there was excellent agreement between EIA and RIA results.