Sample records for false positive reaction

  1. Phenolphthalein false-positive reactions from legume root nodules.

    PubMed

    Petersen, Daniel; Kovacs, Frank

    2014-03-01

    Presumptive tests for blood play a critical role in the examination of physical evidence and in the determination of subsequent analysis. The catalytic power of hemoglobin allows colorimetric reactions employing phenolphthalein (Kastle-Meyer test) to indicate "whether" blood is present. Consequently, DNA profiles extracted from phenolphthalein-positive stains are presumed to be from blood on the evidentiary item and can lead to the identification of "whose" blood is present. Crushed nodules from a variety of legumes yielded phenolphthalein false-positive reactions that were indistinguishable from true bloodstains both in color quality and in developmental time frame. Clothing and other materials stained by nodules also yielded phenolphthalein false-positive reactivity for several years after nodule exposure. Nodules from leguminous plants contain a protein (leghemoglobin) which is structurally and functionally similar to hemoglobin. Testing of purified leghemoglobin confirmed this protein as a source of phenolphthalein reactivity. A scenario is presented showing how the presence of leghemoglobin from nodule staining can mislead investigators. © 2013 American Academy of Forensic Sciences.

  2. An analysis of false positive reactions occurring with the Captia Syph G EIA.

    PubMed Central

    Ross, J; Moyes, A; Young, H; McMillan, A

    1991-01-01

    AIM--The Captia Syph G enzyme immuno assay (EAI) offers the potential for the rapid automated detection of syphilis antibodies. This study was designed to assess the role of other sexually transmitted diseases (STDs) in producing false positive reactions in the Captia Syph G EIA. The role of rheumatoid factor (RF) as a potential source of false positives was also analysed. METHODS--Patients who attended a genitourinary medicine (GUM) department and gave a false positive reaction with the EIA between 1988 and 1990 were compared with women undergoing antenatal testing and with the control clinic population (EIA negative) over the same time period. The incidence of sexually transmitted disease (STD) in the clinic population and the false positive reactors was measured in relation to gonorrhoea, chlamydia, genital warts, candidiasis, "other conditions not requiring treatment" and "other conditions requiring treatment." Male: female sex ratios were also compared. Ninety two RF positive sera were analysed with the EIA. RESULTS--The rate of false positive reactions did not differ with respect to the diagnosis within the GUM clinic population. The antenatal group of women, however, had a lower incidence of false positive reactions than the GUM clinic group. No RF positive sera were positive on Captia Syph G EIA testing. CONCLUSIONS--There is no cross reaction between Captia Syph G EIA and any specific STD or with RF positive sera. The lower incidence of false positive reactions in antenatal women is unexplained but may be related to physiological changes associated with pregnancy. PMID:1743715

  3. [Analysis of false-positive reaction for bacterial detection of blood samples with the automated microbial detection system BacT/ALERT 3D].

    PubMed

    Zhu, Li-Wei; Yang, Xue-Mei; Xu, Xiao-Qin; Xu, Jian; Lu, Huang-Jun; Yan, Li-Xing

    2008-10-01

    This study was aimed to analyze the results of false positive reaction in bacterial detection of blood samples with BacT/ALERT 3D system, to evaluate the specificity of this system, and to decrease the false positive reaction. Each reaction flasks in past five years were processed for bacteria isolation and identification. When the initial cultures were positive, the remaining samples and the corresponding units were recultured if still available. 11395 blood samples were detected. It is worthy of note that the incubator temperature should be stabilized, avoiding fluctuation; when the cultures were alarmed, the reaction flasks showed be kept some hours for further incubation so as to trace a sharply increasing signal to support the judgement of true bacterial growth. The results indicated that 122 samples (1.07%) wee positive at initial culture, out of them 107 samples (88.7%) were found bacterial, and 15 samples (12.3%) were found nothing. The detection curves of positive samples resulted from bacterial growth showed ascent. In conclusion, maintenance of temperature stability and avoidance of temperature fluctuation in incubator could decrease the occurrence of false-positive reaction in detection process. The reaction flasks with positive results at initial culture should be recultured, and whether existence of a sharply ascending logarilhimic growth phase in bacterial growth curve should be further detected, which are helpful to distinguish false-positive reactions from true positive, and thus increase the specificity of the BacT/ALERT system.

  4. False Position, Double False Position and Cramer's Rule

    ERIC Educational Resources Information Center

    Boman, Eugene

    2009-01-01

    We state and prove the methods of False Position (Regula Falsa) and Double False Position (Regula Duorum Falsorum). The history of both is traced from ancient Egypt and China through the work of Fibonacci, ending with a connection between Double False Position and Cramer's Rule.

  5. Frequency of false-negative reactions to the fragrance mix.

    PubMed

    de Groot, A C; van der Kley, A M; Bruynzeel, D P; Meinardi, M M; Smeenk, G; van Joost, T; Pavel, S

    1993-03-01

    To estimate the frequency of false-negative reactions to the fragrance mix, the 8 constituents of the mix in concentrations of 5% (2% for cinnamic aldehyde) were added to the European standard series for routine testing. Patients with positive reactions to individual ingredients in the absence of a reaction to the mix were retested with serial dilutions. In a 4-month period, 677 patients were tested. 61 (9%) reacted to the mix and to 1 or more of the ingredients. 4 patients (0.6% of all patients tested and 6.2% of the patients allergic to fragrances) had false-negative reactions to the mix. They were allergic to cinnamic alcohol, geraniol, isoeugenol and oak moss (1 reaction each), in the absence of a reaction to the fragrance mix. It is concluded that the currently used concentration of the mix (8 x 1%) not infrequently results in false-negative reactions, and that further research should be done to overcome this problem.

  6. Oxybuprocaine induces a false-positive response in immunochromatographic SAS Adeno Test.

    PubMed

    Hoshino, Takeshi; Takanashi, Taiji; Okada, Morio; Uchida, Sunao

    2002-04-01

    To investigate whether a solution of oxybuprocaine hydrochloride, 0.4%, results in a false-positive response in an immunochromatographic SAS Adeno Test. Experimental study. Physiologic saline and 2% lidocaine. Each chemical (100 microl) was diluted in a transport medium. Five drops (200 microl) of the resultant solution were dispensed into the round sample well of a test device. Fifteen samples were tested in each group. Ten minutes after the start of the test, a colored line in the "specimen" portion of the test membrane was visually read as positive or negative by a masked technician. No positive reaction was observed in the control groups (physiologic saline and lidocaine). A false-positive reaction was observed in six samples (33.3%) in the oxybuprocaine group. The positive rate was significantly higher in the oxybuprocaine group compared with those in control groups (P = 0.0062, Fisher's extract probability test). Oxybuprocaine may induce a false-positive reaction in an immunochromatographic SAS Adeno Test. We recommend the use of lidocaine, instead of oxybuprocaine, for local anesthesia in taking eye swabs from patients with suspected adenovirus infection.

  7. Kepler Certified False Positive Table

    NASA Technical Reports Server (NTRS)

    Bryson, Stephen T.; Batalha, Natalie Marie; Colon, Knicole Dawn; Coughlin, Jeffrey Langer; Haas, Michael R.; Henze, Chris; Huber, Daniel; Morton, Tim; Rowe, Jason Frank; Mullally, Susan Elizabeth; hide

    2017-01-01

    This document describes the Kepler Certied False Positive table hosted at the Exoplanet Archive1, herein referred to as the CFP table. This table is the result of detailed examination by the Kepler False Positive Working Group (FPWG) of declared false positives in the Kepler Object of Interest (KOI) tables (see, for example, Batalha et al. (2012); Burke et al.(2014); Rowe et al. (2015); Mullally et al. (2015); Coughlin et al. (2015b)) at the Exoplanet Archive. A KOI is considered a false positive if it is not due to a planet orbiting the KOI's target star. The CFP table contains all KOIs in the Exoplanet Archive cumulative KOI table. The purpose of the CFP table is to provide a list of certified false positive KOIs. A KOI is certified as a false positive when, in the judgement of the FPWG, there is no plausible planetary interpretation of the observational evidence, which we summarize by saying that the evidence for a false positive is compelling. This certification process involves detailed examination using all available data for each KOI, establishing a high-reliability ground truth set. The CFP table can be used to estimate the reliability of, for example, the KOI tables which are created using only Kepler photometric data, so the disposition of individual KOIs may differ in the KOI and CFP tables. Follow-up observers may find the CFP table useful to avoid observing false positives.

  8. Diagnosing periprosthetic infection: false-positive intraoperative Gram stains.

    PubMed

    Oethinger, Margret; Warner, Debra K; Schindler, Susan A; Kobayashi, Hideo; Bauer, Thomas W

    2011-04-01

    Intraoperative Gram stains have a reported low sensitivity but high specificity when used to help diagnose periprosthetic infections. In early 2008, we recognized an unexpectedly high frequency of apparent false-positive Gram stains from revision arthroplasties. The purpose of this report is to describe the cause of these false-positive test results. We calculated the sensitivity and specificity of all intraoperative Gram stains submitted from revision arthroplasty cases during a 3-month interval using microbiologic cultures of the same samples as the gold standard. Methods of specimen harvesting, handling, transport, distribution, specimen processing including tissue grinding/macerating, Gram staining, and interpretation were studied. After a test modification, results of specimens were prospectively collected for a second 3-month interval, and the sensitivity and specificity of intraoperative Gram stains were calculated. The retrospective review of 269 Gram stains submitted from revision arthroplasties indicated historic sensitivity and specificity values of 23% and 92%, respectively. Systematic analysis of all steps of the procedure identified Gram-stained but nonviable bacteria in commercial broth reagents used as diluents for maceration of periprosthetic membranes before Gram staining and culture. Polymerase chain reaction and sequencing showed mixed bacterial DNA. Evaluation of 390 specimens after initiating standardized Millipore filtering of diluent fluid revealed a reduced number of positive Gram stains, yielding 9% sensitivity and 99% specificity. Clusters of false-positive Gram stains have been reported in other clinical conditions. They are apparently rare related to diagnosing periprosthetic infections but have severe consequences if used to guide treatment. Even occasional false-positive Gram stains should prompt review of laboratory methods. Our observations implicate dead bacteria in microbiologic reagents as potential sources of false-positive Gram

  9. False positives in psychiatric diagnosis: implications for human freedom.

    PubMed

    Wakefield, Jerome C

    2010-02-01

    Current symptom-based DSM and ICD diagnostic criteria for mental disorders are prone to yielding false positives because they ignore the context of symptoms. This is often seen as a benign flaw because problems of living and emotional suffering, even if not true disorders, may benefit from support and treatment. However, diagnosis of a disorder in our society has many ramifications not only for treatment choice but for broader social reactions to the diagnosed individual. In particular, mental disorders impose a sick role on individuals and place a burden upon them to change; thus, disorders decrease the level of respect and acceptance generally accorded to those with even annoying normal variations in traits and features. Thus, minimizing false positives is important to a pluralistic society. The harmful dysfunction analysis of disorder is used to diagnose the sources of likely false positives, and propose potential remedies to the current weaknesses in the validity of diagnostic criteria.

  10. Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

    PubMed

    Shanks, Leslie; Ritmeijer, Koert; Piriou, Erwan; Siddiqui, M Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Masiga, Johnson; Abebe, Almaz

    2015-01-01

    Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL) infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals. Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs) was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367) in the VL group compared to 7.9% (200/2526) in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively). The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study.

  11. Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

    PubMed Central

    Shanks, Leslie; Ritmeijer, Koert; Piriou, Erwan; Siddiqui, M. Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Masiga, Johnson; Abebe, Almaz

    2015-01-01

    Background Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL) infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals. Methodology/Principal Findings Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs) was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367) in the VL group compared to 7.9% (200/2526) in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively). Conclusion The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study. PMID:26161864

  12. False Positives in Exoplanet Detection

    NASA Astrophysics Data System (ADS)

    Leuquire, Jacob; Kasper, David; Jang-Condell, Hannah; Kar, Aman; Sorber, Rebecca; Suhaimi, Afiq; KELT (Kilodegree Extremely Little Telescope)

    2018-06-01

    Our team at the University of Wyoming uses a 0.6 m telescope at RBO (Red Buttes Observatory) to help confirm results on potential exoplanet candidates from low resolution, wide field surveys shared by the KELT (Kilodegree Extremely Little Telescope) team. False positives are common in this work. We carry out transit photometry, and this method comes with special types of false positives. The most common false positive seen at the confirmation level is an EB (eclipsing binary). Low resolution images are great in detecting multiple sources for photometric dips in light curves, but they lack the precision to decipher single targets at an accurate level. For example, target star KC18C030621 needed RBO’s photometric precision to determine there was a nearby EB causing exoplanet type light curves. Identifying false positives with our telescope is important work because it helps eliminate the waste of time taken by more expensive telescopes trying to rule out negative candidate stars. It also furthers the identification of other types of photometric events, like eclipsing binaries, so they can be studied on their own.

  13. False Positive and False Negative Effects on Network Attacks

    NASA Astrophysics Data System (ADS)

    Shang, Yilun

    2018-01-01

    Robustness against attacks serves as evidence for complex network structures and failure mechanisms that lie behind them. Most often, due to detection capability limitation or good disguises, attacks on networks are subject to false positives and false negatives, meaning that functional nodes may be falsely regarded as compromised by the attacker and vice versa. In this work, we initiate a study of false positive/negative effects on network robustness against three fundamental types of attack strategies, namely, random attacks (RA), localized attacks (LA), and targeted attack (TA). By developing a general mathematical framework based upon the percolation model, we investigate analytically and by numerical simulations of attack robustness with false positive/negative rate (FPR/FNR) on three benchmark models including Erdős-Rényi (ER) networks, random regular (RR) networks, and scale-free (SF) networks. We show that ER networks are equivalently robust against RA and LA only when FPR equals zero or the initial network is intact. We find several interesting crossovers in RR and SF networks when FPR is taken into consideration. By defining the cost of attack, we observe diminishing marginal attack efficiency for RA, LA, and TA. Our finding highlights the potential risk of underestimating or ignoring FPR in understanding attack robustness. The results may provide insights into ways of enhancing robustness of network architecture and improve the level of protection of critical infrastructures.

  14. False-positive cancer screens and health-related quality of life.

    PubMed

    McGovern, Patricia M; Gross, Cynthia R; Krueger, Richard A; Engelhard, Deborah A; Cordes, Jill E; Church, Timothy R

    2004-01-01

    By design, screening tests are imperfect-unresponsive to some cancers (false negatives) while occasionally raising suspicion of cancer where none exists (false positives). This pilot study describes patients' responses to having a false-positive screening test for cancer, and identifies screening effects on health-related quality of life (HRQoL). The pilot findings suggest issues important for incorporation in future evaluations of the impact of screening for prostate, lung, colon, or ovarian (PLCO) cancers. Seven focus groups were conducted to identify the nature and meaning of all phases of PLCO screening. Minnesota participants in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial who had completed screening, with at least 1 false-positive screen, participated (N = 47). Participants' reactions to abnormal screens and diagnostic work-ups were primarily emotional (eg, anxiety and distress), not physical, and ultimately positive for the majority. Health distress and fear of cancer and death were the major negative aspects of HRQoL identified. These concepts are not typically included in generic HRQoL questionnaires like the SF-36, but are highly relevant to PLCO screening. Clinicians were regarded as underestimating the discomfort of follow-up diagnostic testing. However, relief and assurance appeared to eventually outweigh the negative emotions for most participants. Implications for oncology nurses include the need to consider the emotional consequences of screening in association with screen reliability and validity.

  15. False positive malaria rapid diagnostic test in returning traveler with typhoid fever.

    PubMed

    Meatherall, Bonnie; Preston, Keith; Pillai, Dylan R

    2014-07-09

    Rapid diagnostic tests play a pivotal role in the early diagnosis of malaria where microscopy or polymerase chain reaction are not immediately available. We report the case of a 39 year old traveler to Canada who presented with fever, headache, and abdominal pain after visiting friends and relatives in India. While in India, the individual was not ill and had no signs or symptoms of malaria. Laboratory testing upon his return to Canada identified a false positive malaria rapid diagnostic (BinaxNOW® malaria) result for P. falciparum with coincident Salmonella Typhi bacteraemia without rheumatoid or autoimmune factors. Rapid diagnostic test false positivity for malaria coincided with the presence or absence of Salmonella Typhi in the blood. Clinicians should be aware that Salmonella Typhi infection may result in a false positive malaria rapid diagnostic test. The mechanism of this cross-reactivity is not clear.

  16. Generalized site occupancy models allowing for false positive and false negative errors

    USGS Publications Warehouse

    Royle, J. Andrew; Link, W.A.

    2006-01-01

    Site occupancy models have been developed that allow for imperfect species detection or ?false negative? observations. Such models have become widely adopted in surveys of many taxa. The most fundamental assumption underlying these models is that ?false positive? errors are not possible. That is, one cannot detect a species where it does not occur. However, such errors are possible in many sampling situations for a number of reasons, and even low false positive error rates can induce extreme bias in estimates of site occupancy when they are not accounted for. In this paper, we develop a model for site occupancy that allows for both false negative and false positive error rates. This model can be represented as a two-component finite mixture model and can be easily fitted using freely available software. We provide an analysis of avian survey data using the proposed model and present results of a brief simulation study evaluating the performance of the maximum-likelihood estimator and the naive estimator in the presence of false positive errors.

  17. A Closer Look at Self-Reported Suicide Attempts: False Positives and False Negatives

    ERIC Educational Resources Information Center

    Ploderl, Martin; Kralovec, Karl; Yazdi, Kurosch; Fartacek, Reinhold

    2011-01-01

    The validity of self-reported suicide attempt information is undermined by false positives (e.g., incidences without intent to die), or by unreported suicide attempts, referred to as false negatives. In a sample of 1,385 Austrian adults, we explored the occurrence of false positives and false negatives with detailed, probing questions. Removing…

  18. The Dutch Brucella abortus monitoring programme for cattle: the impact of false-positive serological reactions and comparison of serological tests.

    PubMed

    Emmerzaal, A; de Wit, J J; Dijkstra, Th; Bakker, D; van Zijderveld, F G

    2002-02-01

    The Dutch national Brucella abortus eradication programme for cattle started in 1959. Sporadic cases occurred yearly until 1995; the last infected herd was culled in 1996. In August 1999 the Netherlands was declared officially free of bovine brucellosis by the European Union. Before 1999, the programme to monitor the official Brucella-free status of bovine herds was primarily based on periodical testing of dairy herds with the milk ring test (MRT) and serological testing of all animals older than 1 year of age from non-dairy herds, using the micro-agglutination test (MAT) as screening test. In addition, serum samples of cattle that aborted were tested with the MAT. The high number of false positive reactions in both tests and the serum agglutination test (SAT) and complement fixation test (CFT) used for confirmation seemed to result in unnecessary blockade of herds, subsequent testing and slaughter of animals. For this reason, a validation study was performed in which three indirect enzyme-linked immunosorbent assays (ELISAs), the CFT and the SAT were compared using a panel of sera from brucellosis-free cattle, sera from experimentally infected cattle, and sera from cattle experimentally infected with bacteria which are known to induce cross-reactive antibodies (Pasteurella, Salmonella, Yersinia, and Escherichia). Moreover, four ELISAs and the MRT were compared using a panel of 1000 bulk milk samples from Brucella-free herds and 12 milk samples from Brucella abortus- infected cattle. It is concluded that the ELISA obtained from ID-Lelystad is the most suitable test to monitor the brucelosis free status of herds because it gives rise to fewer false-positive reactions than the SAT.

  19. The problem of false positives and false negatives in violent video game experiments.

    PubMed

    Ferguson, Christopher J

    The problem of false positives and negatives has received considerable attention in behavioral research in recent years. The current paper uses video game violence research as an example of how such issues may develop in a field. Despite decades of research, evidence on whether violent video games (VVGs) contribute to aggression in players has remained mixed. Concerns have been raised in recent years that experiments regarding VVGs may suffer from both "false positives" and "false negatives." The current paper examines this issue in three sets of video game experiments, two sets of video game experiments on aggression and prosocial behaviors identified in meta-analysis, and a third group of recent null studies. Results indicated that studies of VVGs and aggression appear to be particularly prone to false positive results. Studies of VVGs and prosocial behavior, by contrast are heterogeneous and did not demonstrate any indication of false positive results. However, their heterogeneous nature made it difficult to base solid conclusions on them. By contrast, evidence for false negatives in null studies was limited, and little evidence emerged that null studies lacked power in comparison those highlighted in past meta-analyses as evidence for effects. These results are considered in light of issues related to false positives and negatives in behavioral science more broadly. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Characterisation of false-positive observations in botanical surveys

    PubMed Central

    2017-01-01

    Errors in botanical surveying are a common problem. The presence of a species is easily overlooked, leading to false-absences; while misidentifications and other mistakes lead to false-positive observations. While it is common knowledge that these errors occur, there are few data that can be used to quantify and describe these errors. Here we characterise false-positive errors for a controlled set of surveys conducted as part of a field identification test of botanical skill. Surveys were conducted at sites with a verified list of vascular plant species. The candidates were asked to list all the species they could identify in a defined botanically rich area. They were told beforehand that their final score would be the sum of the correct species they listed, but false-positive errors counted against their overall grade. The number of errors varied considerably between people, some people create a high proportion of false-positive errors, but these are scattered across all skill levels. Therefore, a person’s ability to correctly identify a large number of species is not a safeguard against the generation of false-positive errors. There was no phylogenetic pattern to falsely observed species; however, rare species are more likely to be false-positive as are species from species rich genera. Raising the threshold for the acceptance of an observation reduced false-positive observations dramatically, but at the expense of more false negative errors. False-positive errors are higher in field surveying of plants than many people may appreciate. Greater stringency is required before accepting species as present at a site, particularly for rare species. Combining multiple surveys resolves the problem, but requires a considerable increase in effort to achieve the same sensitivity as a single survey. Therefore, other methods should be used to raise the threshold for the acceptance of a species. For example, digital data input systems that can verify, feedback and inform the

  1. [EXPERIENCE OF STUDY AND POSSIBLE WAYS OF ELIMINATION OF FALSE POSITIVE AND FALSE NEGATIVE RESULTS DURING EXECUTION OF POLYMERASE CHAIN REACTION ON AN EXAMPLE OF JUNIN VIRUS RNA DETECTION].

    PubMed

    Sizikova, T E; Lebedev, V N; Pantyukhov, V B; Borisevich, S V; Merkulov, V A

    2015-01-01

    Experience of study and possible ways of elimination of false positive and false negative results during execution of polymerase chain reaction on an example of Junin virus RNA detection. MATERIALSS AND METHODS: Junin virus--causative agent of Argentine hemorrhagic fever (AHF) strain XJpR37/5787 was obtained from the State collection of pathogenicity group I causative agents of the 48th Central Research Institute. Reagent kit for detection of Junin virus RNA by RT-PCR was developed in the Institute and consists of 4 sets: for isolation of RNA, execution of reverse-transcription reaction, execution of PCR and electrophoretic detection of PCR products. RT-PCR was carried out by a standard technique. Continuous cell cultures of African green monkey Vero B, GMK-AH-1(D) were obtained from the museum of cell culture department of the Centre. An experimental study of the effect of various factors of impact on the sample under investigation ("thawing-freezing", presence of formaldehyde, heparin) on the obtaining of false negative results during Junin virus RNA detection by using RT-PCR was studied. Addition of 0.01% heparin to the samples was shown to completely inhibit PCR. Addition of 0.05% formaldehyde significantly reduces sensitivity of the method. A possibility of reduction of analysis timeframe from 15 to 5 days was shown during detection of the causative agent in samples with low concentration of the latter by growing the samples and subsequent analysis of the material obtained by using RT-PCR. During detection of causative agent by using RT-PCR false negative results could appear in the presence of formaldehyde and heparin in the sample. A possibility of elimination of false negative PCR results due to concentration of the causative agent in the sample under investigation at a level below sensitivity threshold was shown on the example of Junin virus RNA detection by using growing of the pathogen in appropriate accumulation system with subsequent analysis of the

  2. "False Positive" Claims of Near-Death Experiences and "False Negative" Denials of Near-Death Experiences

    ERIC Educational Resources Information Center

    Greyson, Bruce

    2005-01-01

    Some persons who claim to have had near-death experiences (NDEs) fail research criteria for having had NDEs ("false positives"); others who deny having had NDEs do meet research criteria for having had NDEs ("false negatives"). The author evaluated false positive claims and false negative denials in an organization that promotes near-death…

  3. A statistical model of false negative and false positive detection of phase singularities.

    PubMed

    Jacquemet, Vincent

    2017-10-01

    The complexity of cardiac fibrillation dynamics can be assessed by analyzing the distribution of phase singularities (PSs) observed using mapping systems. Interelectrode distance, however, limits the accuracy of PS detection. To investigate in a theoretical framework the PS false negative and false positive rates in relation to the characteristics of the mapping system and fibrillation dynamics, we propose a statistical model of phase maps with controllable number and locations of PSs. In this model, phase maps are generated from randomly distributed PSs with physiologically-plausible directions of rotation. Noise and distortion of the phase are added. PSs are detected using topological charge contour integrals on regular grids of varying resolutions. Over 100 × 10 6 realizations of the random field process are used to estimate average false negative and false positive rates using a Monte-Carlo approach. The false detection rates are shown to depend on the average distance between neighboring PSs expressed in units of interelectrode distance, following approximately a power law with exponents in the range of 1.14 to 2 for false negatives and around 2.8 for false positives. In the presence of noise or distortion of phase, false detection rates at high resolution tend to a non-zero noise-dependent lower bound. This model provides an easy-to-implement tool for benchmarking PS detection algorithms over a broad range of configurations with multiple PSs.

  4. False Positive Probabilities for all Kepler Objects of Interest: 1284 Newly Validated Planets and 428 Likely False Positives

    NASA Astrophysics Data System (ADS)

    Morton, Timothy D.; Bryson, Stephen T.; Coughlin, Jeffrey L.; Rowe, Jason F.; Ravichandran, Ganesh; Petigura, Erik A.; Haas, Michael R.; Batalha, Natalie M.

    2016-05-01

    We present astrophysical false positive probability calculations for every Kepler Object of Interest (KOI)—the first large-scale demonstration of a fully automated transiting planet validation procedure. Out of 7056 KOIs, we determine that 1935 have probabilities <1% of being astrophysical false positives, and thus may be considered validated planets. Of these, 1284 have not yet been validated or confirmed by other methods. In addition, we identify 428 KOIs that are likely to be false positives, but have not yet been identified as such, though some of these may be a result of unidentified transit timing variations. A side product of these calculations is full stellar property posterior samplings for every host star, modeled as single, binary, and triple systems. These calculations use vespa, a publicly available Python package that is able to be easily applied to any transiting exoplanet candidate.

  5. Designing occupancy studies when false-positive detections occur

    USGS Publications Warehouse

    Clement, Matthew

    2016-01-01

    1.Recently, estimators have been developed to estimate occupancy probabilities when false-positive detections occur during presence-absence surveys. Some of these estimators combine different types of survey data to improve estimates of occupancy. With these estimators, there is a tradeoff between the number of sample units surveyed, and the number and type of surveys at each sample unit. Guidance on efficient design of studies when false positives occur is unavailable. 2.For a range of scenarios, I identified survey designs that minimized the mean square error of the estimate of occupancy. I considered an approach that uses one survey method and two observation states and an approach that uses two survey methods. For each approach, I used numerical methods to identify optimal survey designs when model assumptions were met and parameter values were correctly anticipated, when parameter values were not correctly anticipated, and when the assumption of no unmodelled detection heterogeneity was violated. 3.Under the approach with two observation states, false positive detections increased the number of recommended surveys, relative to standard occupancy models. If parameter values could not be anticipated, pessimism about detection probabilities avoided poor designs. Detection heterogeneity could require more or fewer repeat surveys, depending on parameter values. If model assumptions were met, the approach with two survey methods was inefficient. However, with poor anticipation of parameter values, with detection heterogeneity, or with removal sampling schemes, combining two survey methods could improve estimates of occupancy. 4.Ignoring false positives can yield biased parameter estimates, yet false positives greatly complicate the design of occupancy studies. Specific guidance for major types of false-positive occupancy models, and for two assumption violations common in field data, can conserve survey resources. This guidance can be used to design efficient

  6. Occupancy models for data with false positive and false negative errors and heterogeneity across sites and surveys

    Treesearch

    Paige F.B. Ferguson; Michael J. Conroy; Jeffrey Hepinstall-Cymerman; Nigel Yoccoz

    2015-01-01

    False positive detections, such as species misidentifications, occur in ecological data, although many models do not account for them. Consequently, these models are expected to generate biased inference.The main challenge in an analysis of data with false positives is to distinguish false positive and false negative...

  7. False-positive results in pharmacoepidemiology and pharmacovigilance.

    PubMed

    Bezin, Julien; Bosco-Levy, Pauline; Pariente, Antoine

    2017-09-01

    False-positive constitute an important issue in scientific research. In the domain of drug evaluation, it affects all phases of drug development and assessment, from the very early preclinical studies to the late post-marketing evaluations. The core concern associated with this false-positive is the lack of replicability of the results. Aside from fraud or misconducts, false-positive is often envisioned from the statistical angle, which considers them as a price to pay for type I error in statistical testing, and its inflation in the context of multiple testing. If envisioning this problematic in the context of pharmacoepidemiology and pharmacovigilance however, that both evaluate drugs in an observational settings, information brought by statistical testing and the significance of such should only be considered as additional to the estimates provided and their confidence interval, in a context where differences have to be a clinically meaningful upon everything, and the results appear robust to the biases likely to have affected the studies. In the following article, we consequently illustrate these biases and their consequences in generating false-positive results, through studies and associations between drug use and health outcomes that have been widely disputed. Copyright © 2017 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.

  8. Detecting false positives in multielement designs: implications for brief assessments.

    PubMed

    Bartlett, Sara M; Rapp, John T; Henrickson, Marissa L

    2011-11-01

    The authors assessed the extent to which multielement designs produced false positives using continuous duration recording (CDR) and interval recording with 10-s and 1-min interval sizes. Specifically, they created 6,000 graphs with multielement designs that varied in the number of data paths, and the number of data points per data path, using a random number generator. In Experiment 1, the authors visually analyzed the graphs for the occurrence of false positives. Results indicated that graphs depicting only two sessions for each condition (e.g., a control condition plotted with multiple test conditions) produced the highest percentage of false positives for CDR and interval recording with 10-s and 1-min intervals. Conversely, graphs with four or five sessions for each condition produced the lowest percentage of false positives for each method. In Experiment 2, they applied two new rules, which were intended to decrease false positives, to each graph that depicted a false positive in Experiment 1. Results showed that application of new rules decreased false positives to less than 5% for all of the graphs except for those with two data paths and two data points per data path. Implications for brief assessments are discussed.

  9. Implications of false-positive results for future cancer screenings.

    PubMed

    Taksler, Glen B; Keating, Nancy L; Rothberg, Michael B

    2018-06-01

    False-positive cancer screening results may affect a patient's willingness to obtain future screening. The authors conducted logistic regression analysis of 450,484 person-years of electronic medical records (2006-2015) in 92,405 individuals aged 50 to 75 years. Exposures were false-positive breast, prostate, or colorectal cancer screening test results (repeat breast imaging or negative breast biopsy ≤3 months after screening mammography, repeat prostate-specific antigen [PSA] test ≤3 months after PSA test result ≥4.0 ng/mL or negative prostate biopsy ≤3 months after any PSA result, or negative colonoscopy [without biopsy/polypectomy] ≤6 months after a positive fecal occult blood test). Outcomes were up-to-date status with breast or colorectal cancer screening. Covariates included prior screening history, clinical information (eg, family history, obesity, and smoking status), comorbidity, and demographics. Women were more likely to be up to date with breast cancer screening if they previously had false-positive mammography findings (adjusted odds ratio [AOR], 1.43 [95% confidence interval, 1.34-1.51] without breast biopsy and AOR, 2.02 [95% confidence interval, 1.56-2.62] with breast biopsy; both P<.001). The same women were more likely to be up to date with colorectal cancer screening (AOR range, 1.25-1.47 depending on breast biopsy; both P<.001). Men who previously had false-positive PSA testing were more likely to be up to date with colorectal cancer screening (AOR, 1.22 [P = .039] without prostate imaging/biopsy and AOR, 1.60 [P = .028] with imaging/biopsy). Results were stronger for individuals with more false-positive results (all P≤.005). However, women with previous false-positive colorectal cancer fecal occult blood test screening results were found to be less likely to be up to date with breast cancer screening (AOR, 0.73; P<.001). Patients who previously had a false-positive breast or prostate cancer screening test were more likely to engage

  10. Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives.

    PubMed

    Wolf, Max; Kurvers, Ralf H J M; Ward, Ashley J W; Krause, Stefan; Krause, Jens

    2013-04-07

    In a wide range of contexts, including predator avoidance, medical decision-making and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives; conversely, decreased false positives are associated with decreased true positives. We use an integrated theoretical and experimental approach to show that a group of decision-makers can overcome this basic limitation. Using a mathematical model, we show that a simple quorum decision rule enables individuals in groups to simultaneously increase true positives and decrease false positives. The results from a predator-detection experiment that we performed with humans are in line with these predictions: (i) after observing the choices of the other group members, individuals both increase true positives and decrease false positives, (ii) this effect gets stronger as group size increases, (iii) individuals use a quorum threshold set between the average true- and false-positive rates of the other group members, and (iv) individuals adjust their quorum adaptively to the performance of the group. Our results have broad implications for our understanding of the ecology and evolution of group-living animals and lend themselves for applications in the human domain such as the design of improved screening methods in medical, forensic, security and business applications.

  11. Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives

    PubMed Central

    Wolf, Max; Kurvers, Ralf H. J. M.; Ward, Ashley J. W.; Krause, Stefan; Krause, Jens

    2013-01-01

    In a wide range of contexts, including predator avoidance, medical decision-making and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives; conversely, decreased false positives are associated with decreased true positives. We use an integrated theoretical and experimental approach to show that a group of decision-makers can overcome this basic limitation. Using a mathematical model, we show that a simple quorum decision rule enables individuals in groups to simultaneously increase true positives and decrease false positives. The results from a predator-detection experiment that we performed with humans are in line with these predictions: (i) after observing the choices of the other group members, individuals both increase true positives and decrease false positives, (ii) this effect gets stronger as group size increases, (iii) individuals use a quorum threshold set between the average true- and false-positive rates of the other group members, and (iv) individuals adjust their quorum adaptively to the performance of the group. Our results have broad implications for our understanding of the ecology and evolution of group-living animals and lend themselves for applications in the human domain such as the design of improved screening methods in medical, forensic, security and business applications. PMID:23407830

  12. Risk of breast cancer after false-positive results in mammographic screening.

    PubMed

    Román, Marta; Castells, Xavier; Hofvind, Solveig; von Euler-Chelpin, My

    2016-06-01

    Women with false-positive results are commonly referred back to routine screening. Questions remain regarding their long-term outcome of breast cancer. We assessed the risk of screen-detected breast cancer in women with false-positive results. We conducted a joint analysis using individual level data from the population-based screening programs in Copenhagen and Funen in Denmark, Norway, and Spain. Overall, 150,383 screened women from Denmark (1991-2008), 612,138 from Norway (1996-2010), and 1,172,572 from Spain (1990-2006) were included. Poisson regression was used to estimate the relative risk (RR) of screen-detected cancer for women with false-positive versus negative results. We analyzed information from 1,935,093 women 50-69 years who underwent 6,094,515 screening exams. During an average 5.8 years of follow-up, 230,609 (11.9%) women received a false-positive result and 27,849 (1.4%) were diagnosed with screen-detected cancer. The adjusted RR of screen-detected cancer after a false-positive result was 2.01 (95% CI: 1.93-2.09). Women who tested false-positive at first screen had a RR of 1.86 (95% CI: 1.77-1.96), whereas those who tested false-positive at third screening had a RR of 2.42 (95% CI: 2.21-2.64). The RR of breast cancer at the screening test after the false-positive result was 3.95 (95% CI: 3.71-4.21), whereas it decreased to 1.25 (95% CI: 1.17-1.34) three or more screens after the false-positive result. Women with false-positive results had a twofold risk of screen-detected breast cancer compared to women with negative tests. The risk remained significantly higher three or more screens after the false-positive result. The increased risk should be considered when discussing stratified screening strategies. © 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

  13. Bladder cancer diagnosis with CT urography: test characteristics and reasons for false-positive and false-negative results.

    PubMed

    Trinh, Tony W; Glazer, Daniel I; Sadow, Cheryl A; Sahni, V Anik; Geller, Nina L; Silverman, Stuart G

    2018-03-01

    To determine test characteristics of CT urography for detecting bladder cancer in patients with hematuria and those undergoing surveillance, and to analyze reasons for false-positive and false-negative results. A HIPAA-compliant, IRB-approved retrospective review of reports from 1623 CT urograms between 10/2010 and 12/31/2013 was performed. 710 examinations for hematuria or bladder cancer history were compared to cystoscopy performed within 6 months. Reference standard was surgical pathology or 1-year minimum clinical follow-up. False-positive and false-negative examinations were reviewed to determine reasons for errors. Ninety-five bladder cancers were detected. CT urography accuracy: was 91.5% (650/710), sensitivity 86.3% (82/95), specificity 92.4% (568/615), positive predictive value 63.6% (82/129), and negative predictive value was 97.8% (568/581). Of 43 false positives, the majority of interpretation errors were due to benign prostatic hyperplasia (n = 12), trabeculated bladder (n = 9), and treatment changes (n = 8). Other causes include blood clots, mistaken normal anatomy, infectious/inflammatory changes, or had no cystoscopic correlate. Of 13 false negatives, 11 were due to technique, one to a large urinary residual, one to artifact. There were no errors in perception. CT urography is an accurate test for diagnosing bladder cancer; however, in protocols relying predominantly on excretory phase images, overall sensitivity remains insufficient to obviate cystoscopy. Awareness of bladder cancer mimics may reduce false-positive results. Improvements in CTU technique may reduce false-negative results.

  14. Experimental investigation of false positive errors in auditory species occurrence surveys

    USGS Publications Warehouse

    Miller, David A.W.; Weir, Linda A.; McClintock, Brett T.; Grant, Evan H. Campbell; Bailey, Larissa L.; Simons, Theodore R.

    2012-01-01

    False positive errors are a significant component of many ecological data sets, which in combination with false negative errors, can lead to severe biases in conclusions about ecological systems. We present results of a field experiment where observers recorded observations for known combinations of electronically broadcast calling anurans under conditions mimicking field surveys to determine species occurrence. Our objectives were to characterize false positive error probabilities for auditory methods based on a large number of observers, to determine if targeted instruction could be used to reduce false positive error rates, and to establish useful predictors of among-observer and among-species differences in error rates. We recruited 31 observers, ranging in abilities from novice to expert, that recorded detections for 12 species during 180 calling trials (66,960 total observations). All observers made multiple false positive errors and on average 8.1% of recorded detections in the experiment were false positive errors. Additional instruction had only minor effects on error rates. After instruction, false positive error probabilities decreased by 16% for treatment individuals compared to controls with broad confidence interval overlap of 0 (95% CI: -46 to 30%). This coincided with an increase in false negative errors due to the treatment (26%; -3 to 61%). Differences among observers in false positive and in false negative error rates were best predicted by scores from an online test and a self-assessment of observer ability completed prior to the field experiment. In contrast, years of experience conducting call surveys was a weak predictor of error rates. False positive errors were also more common for species that were played more frequently, but were not related to the dominant spectral frequency of the call. Our results corroborate other work that demonstrates false positives are a significant component of species occurrence data collected by auditory

  15. Categorizing mistaken false positives in regulation of human and environmental health.

    PubMed

    Hansen, Steffen Foss; Krayer von Krauss, Martin P; Tickner, Joel A

    2007-02-01

    One of the concerns often voiced by critics of the precautionary principle is that a widespread regulatory application of the principle will lead to a large number of false positives (i.e., over-regulation of minor risks and regulation of nonexisting risks). The present article proposes a general definition of a regulatory false positive, and seeks to identify case studies that can be considered authentic regulatory false positives. Through a comprehensive review of the science policy literature for proclaimed false positives and interviews with authorities on regulation and the precautionary principle we identified 88 cases. Following a detailed analysis of these cases, we found that few of the cases mentioned in the literature can be considered to be authentic false positives. As a result, we have developed a number of different categories for these cases of "mistaken false positives," including: real risks, "The jury is still out," nonregulated proclaimed risks, "Too narrow a definition of risk," and risk-risk tradeoffs. These categories are defined and examples are presented in order to illustrate their key characteristics. On the basis of our analysis, we were able to identify only four cases that could be defined as regulatory false positives in the light of today's knowledge and recognized uncertainty: the Southern Corn Leaf Blight, the Swine Flu, Saccharin, and Food Irradiation in relation to consumer health. We conclude that concerns about false positives do not represent a reasonable argument against future application of the precautionary principle.

  16. Diagnostic performance of serological tests for swine brucellosis in the presence of false positive serological reactions.

    PubMed

    Dieste-Pérez, L; Blasco, J M; de Miguel, M J; Moriyón, I; Muñoz, P M

    2015-04-01

    Swine brucellosis caused by Brucella suis biovar 2 is an emerging disease in Europe. Currently used diagnostic tests for swine brucellosis detect antibodies to the O-polysaccharide (O-PS) of Brucella smooth lipopolysaccharide (S-LPS) but their specificity is compromised by false-positive serological reactions (FPSRs) when bacteria carrying cross-reacting O-PS infect pigs. FPSRs occur throughout Europe, and the only tool available for a specific B. suis diagnosis is the intradermal test with Brucella protein extracts free of O-PS or S-LPS. Using sera of 162 sows naturally infected by B. suis biovar 2, 406 brucellosis-free sows, and 218 pigs of brucellosis-free farms affected by FPSR, we assessed the diagnostic performance of an indirect ELISA with rough LPS (thus devoid of O-PS) and of gel immunodiffusion, counterimmunoelectrophoresis, latex agglutination and indirect ELISA with O-PS free proteins in comparison with several S-LPS tests (Rose Bengal, complement fixation, gel immunodiffusion and indirect ELISA). When adjusted to 100% specificity, the sensitivity of the rough LPS ELISA was very low (30%), and adoption of other cut-offs resulted in poor specificity/sensitivity ratios. Although their specificity was 100%, the sensitivity of protein tests (ELISA, latex agglutination, counterimmunoelectrophoresis, and gel immunodiffusion) was only moderate (45, 58, 61 and 63%, respectively). Among S-LPS tests, gel immunodiffusion was the only test showing acceptable sensitivity/specificity (68 and 100%, respectively). Despite these shortcomings, and when the purpose is to screen out FPSR at herd level, gel immunodiffusion tests may offer a technically simple and practical alternative to intradermal testing. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Reducing False Positives in Runtime Analysis of Deadlocks

    NASA Technical Reports Server (NTRS)

    Bensalem, Saddek; Havelund, Klaus; Clancy, Daniel (Technical Monitor)

    2002-01-01

    This paper presents an improvement of a standard algorithm for detecting dead-lock potentials in multi-threaded programs, in that it reduces the number of false positives. The standard algorithm works as follows. The multi-threaded program under observation is executed, while lock and unlock events are observed. A graph of locks is built, with edges between locks symbolizing locking orders. Any cycle in the graph signifies a potential for a deadlock. The typical standard example is the group of dining philosophers sharing forks. The algorithm is interesting because it can catch deadlock potentials even though no deadlocks occur in the examined trace, and at the same time it scales very well in contrast t o more formal approaches to deadlock detection. The algorithm, however, can yield false positives (as well as false negatives). The extension of the algorithm described in this paper reduces the amount of false positives for three particular cases: when a gate lock protects a cycle, when a single thread introduces a cycle, and when the code segments in different threads that cause the cycle can actually not execute in parallel. The paper formalizes a theory for dynamic deadlock detection and compares it to model checking and static analysis techniques. It furthermore describes an implementation for analyzing Java programs and its application to two case studies: a planetary rover and a space craft altitude control system.

  18. Statistical approaches to account for false-positive errors in environmental DNA samples.

    PubMed

    Lahoz-Monfort, José J; Guillera-Arroita, Gurutzeta; Tingley, Reid

    2016-05-01

    Environmental DNA (eDNA) sampling is prone to both false-positive and false-negative errors. We review statistical methods to account for such errors in the analysis of eDNA data and use simulations to compare the performance of different modelling approaches. Our simulations illustrate that even low false-positive rates can produce biased estimates of occupancy and detectability. We further show that removing or classifying single PCR detections in an ad hoc manner under the suspicion that such records represent false positives, as sometimes advocated in the eDNA literature, also results in biased estimation of occupancy, detectability and false-positive rates. We advocate alternative approaches to account for false-positive errors that rely on prior information, or the collection of ancillary detection data at a subset of sites using a sampling method that is not prone to false-positive errors. We illustrate the advantages of these approaches over ad hoc classifications of detections and provide practical advice and code for fitting these models in maximum likelihood and Bayesian frameworks. Given the severe bias induced by false-negative and false-positive errors, the methods presented here should be more routinely adopted in eDNA studies. © 2015 John Wiley & Sons Ltd.

  19. How to limit false positives in environmental DNA and metabarcoding?

    PubMed

    Ficetola, Gentile Francesco; Taberlet, Pierre; Coissac, Eric

    2016-05-01

    Environmental DNA (eDNA) and metabarcoding are boosting our ability to acquire data on species distribution in a variety of ecosystems. Nevertheless, as most of sampling approaches, eDNA is not perfect. It can fail to detect species that are actually present, and even false positives are possible: a species may be apparently detected in areas where it is actually absent. Controlling false positives remains a main challenge for eDNA analyses: in this issue of Molecular Ecology Resources, Lahoz-Monfort et al. () test the performance of multiple statistical modelling approaches to estimate the rate of detection and false positives from eDNA data. Here, we discuss the importance of controlling for false detection from early steps of eDNA analyses (laboratory, bioinformatics), to improve the quality of results and allow an efficient use of the site occupancy-detection modelling (SODM) framework for limiting false presences in eDNA analysis. © 2016 John Wiley & Sons Ltd.

  20. Accounting for false-positive acoustic detections of bats using occupancy models

    USGS Publications Warehouse

    Clement, Matthew J.; Rodhouse, Thomas J.; Ormsbee, Patricia C.; Szewczak, Joseph M.; Nichols, James D.

    2014-01-01

    4. Synthesis and applications. Our results suggest that false positives sufficient to affect inferences may be common in acoustic surveys for bats. We demonstrate an approach that can estimate occupancy, regardless of the false-positive rate, when acoustic surveys are paired with capture surveys. Applications of this approach include monitoring the spread of White-Nose Syndrome, estimating the impact of climate change and informing conservation listing decisions. We calculate a site-specific probability of occupancy, conditional on survey results, which could inform local permitting decisions, such as for wind energy projects. More generally, the magnitude of false positives suggests that false-positive occupancy models can improve accuracy in research and monitoring of bats and provide wildlife managers with more reliable information.

  1. Shear-wave elastography in the diagnosis of solid breast masses: what leads to false-negative or false-positive results?

    PubMed

    Yoon, Jung Hyun; Jung, Hae Kyoung; Lee, Jong Tae; Ko, Kyung Hee

    2013-09-01

    To investigate the factors that have an effect on false-positive or false-negative shear-wave elastography (SWE) results in solid breast masses. From June to December 2012, 222 breast lesions of 199 consecutive women (mean age: 45.3 ± 10.1 years; range, 21 to 88 years) who had been scheduled for biopsy or surgical excision were included. Greyscale ultrasound and SWE were performed in all women before biopsy. Final ultrasound assessments and SWE parameters (pattern classification and maximum elasticity) were recorded and compared with histopathology results. Patient and lesion factors in the 'true' and 'false' groups were compared. Of the 222 masses, 175 (78.8 %) were benign, and 47 (21.2 %) were malignant. False-positive rates of benign masses were significantly higher than false-negative rates of malignancy in SWE patterns, 36.6 % to 6.4 % (P < 0.001). Among both benign and malignant masses, factors showing significance among false SWE features were lesion size, breast thickness and lesion depth (all P < 0.05). All 47 malignant breast masses had SWE images of good quality. False SWE features were more significantly seen in benign masses. Lesion size, breast thickness and lesion depth have significance in producing false results, and this needs consideration in SWE image acquisition. • Shear-wave elastography (SWE) is widely used during breast imaging • At SWE, false-positive rates were significantly higher than false-negative rates • Larger size, breast thickness, depth and fair quality influences false-positive SWE features • Smaller size, larger breast thickness and depth influences false-negative SWE features.

  2. False-positive IgM for CMV in pregnant women with autoimmune disease: a novel prognostic factor for poor pregnancy outcome.

    PubMed

    De Carolis, S; Santucci, S; Botta, A; Garofalo, S; Martino, C; Perrelli, A; Salvi, S; Degennaro, Va; de Belvis, Ag; Ferrazzani, S; Scambia, G

    2010-06-01

    Our aims were to assess the frequency of false-positive IgM antibodies for cytomegalovirus in pregnant women with autoimmune diseases and in healthy women (controls) and to determine their relationship with pregnancy outcome. Data from 133 pregnancies in 118 patients with autoimmune diseases and from 222 pregnancies in 198 controls were assessed. When positive IgM for cytomegalovirus was detected, IgG avidity, cytomegalovirus isolation and polymerase chain reaction for CMV-DNA in maternal urine and amniotic fluid samples were performed in order to identify primary infection or false positivity. A statistically significantly higher rate of false-positive IgM was found in pregnancies with autoimmune diseases (16.5%) in comparison with controls (0.9%). A worse pregnancy outcome was observed among patients with autoimmune disease and false cytomegalovirus IgM in comparison with those without false positivity: earlier week of delivery (p = 0.017), lower neonatal birth weight (p = 0.0004) and neonatal birth weight percentile (p = 0.002), higher rate of intrauterine growth restriction (p = 0.02) and babies weighing less than 2000 g (p = 0.025) were encountered. The presence of false cytomegalovirus IgM in patients with autoimmune diseases could be used as a novel prognostic index of poor pregnancy outcome: it may reflect a non-specific activation of the immune system that could negatively affect pregnancy outcome. Lupus (2010) 19, 844-849.

  3. [A pseudo-outbreak of pharyngeal gonorrhoea related to a false-positive PCR-result].

    PubMed

    Verzijl, A; Berretty, P J M; Erceg, A; Krekels, G A M; Van den Brule, A J C; Boel, C H E

    2007-03-24

    Nucleic acid amplification tests, including the polymerase chain reaction (PCR), are sensitive and specific tests that are often used for diagnosing sexually transmitted diseases (STDs). A pseudo-outbreak of pharyngeal gonorrhoea in a group of prostitutes turned out to have been caused by false-positive test results due to commensal oropharyngeal Neisseria species. Specific molecular tests may yield erroneous results. When the results of an STD study have major consequences at a legal or social level, it is advisable, in consultation with a medical microbiologist, to take a sample for culture or to carry out a second molecular test aimed at a different part of the bacterial genome.

  4. Decisions to shoot in a weapon identification task: The influence of cultural stereotypes and perceived threat on false positive errors.

    PubMed

    Fleming, Kevin K; Bandy, Carole L; Kimble, Matthew O

    2010-01-01

    The decision to shoot a gun engages executive control processes that can be biased by cultural stereotypes and perceived threat. The neural locus of the decision to shoot is likely to be found in the anterior cingulate cortex (ACC), where cognition and affect converge. Male military cadets at Norwich University (N=37) performed a weapon identification task in which they made rapid decisions to shoot when images of guns appeared briefly on a computer screen. Reaction times, error rates, and electroencephalogram (EEG) activity were recorded. Cadets reacted more quickly and accurately when guns were primed by images of Middle-Eastern males wearing traditional clothing. However, cadets also made more false positive errors when tools were primed by these images. Error-related negativity (ERN) was measured for each response. Deeper ERNs were found in the medial-frontal cortex following false positive responses. Cadets who made fewer errors also produced deeper ERNs, indicating stronger executive control. Pupil size was used to measure autonomic arousal related to perceived threat. Images of Middle-Eastern males in traditional clothing produced larger pupil sizes. An image of Osama bin Laden induced the largest pupil size, as would be predicted for the exemplar of Middle East terrorism. Cadets who showed greater increases in pupil size also made more false positive errors. Regression analyses were performed to evaluate predictions based on current models of perceived threat, stereotype activation, and cognitive control. Measures of pupil size (perceived threat) and ERN (cognitive control) explained significant proportions of the variance in false positive errors to Middle-Eastern males in traditional clothing, while measures of reaction time, signal detection response bias, and stimulus discriminability explained most of the remaining variance.

  5. Decisions to Shoot in a Weapon Identification Task: The Influence of Cultural Stereotypes and Perceived Threat on False Positive Errors

    PubMed Central

    Fleming, Kevin K.; Bandy, Carole L.; Kimble, Matthew O.

    2014-01-01

    The decision to shoot engages executive control processes that can be biased by cultural stereotypes and perceived threat. The neural locus of the decision to shoot is likely to be found in the anterior cingulate cortex (ACC) where cognition and affect converge. Male military cadets at Norwich University (N=37) performed a weapon identification task in which they made rapid decisions to shoot when images of guns appeared briefly on a computer screen. Reaction times, error rates, and EEG activity were recorded. Cadets reacted more quickly and accurately when guns were primed by images of middle-eastern males wearing traditional clothing. However, cadets also made more false positive errors when tools were primed by these images. Error-related negativity (ERN) was measured for each response. Deeper ERN’s were found in the medial-frontal cortex following false positive responses. Cadets who made fewer errors also produced deeper ERN’s, indicating stronger executive control. Pupil size was used to measure autonomic arousal related to perceived threat. Images of middle-eastern males in traditional clothing produced larger pupil sizes. An image of Osama bin Laden induced the largest pupil size, as would be predicted for the exemplar of Middle East terrorism. Cadets who showed greater increases in pupil size also made more false positive errors. Regression analyses were performed to evaluate predictions based on current models of perceived threat, stereotype activation, and cognitive control. Measures of pupil size (perceived threat) and ERN (cognitive control) explained significant proportions of the variance in false positive errors to middle-eastern males in traditional clothing, while measures of reaction time, signal detection response bias, and stimulus discriminability explained most of the remaining variance. PMID:19813139

  6. DNA typing by microbead arrays and PCR-SSP: apparent false-negative or -positive hybridization or amplification signals disclose new HLA-B and -DRB1 alleles.

    PubMed

    Rahal, M; Kervaire, B; Villard, J; Tiercy, J-M

    2008-03-01

    Human leukocyte antigen (HLA) typing by polymerase chain reaction-sequence-specific oligonucleotide (PCR-SSO) hybridization on solid phase (microbead assay) or polymerase chain reaction-sequence-specific primers (PCR-SSP) requires interpretation softwares to detect all possible allele combinations. These programs propose allele calls by taking into account false-positive or false-negative signal(s). The laboratory has the option to validate typing results in the presence of strongly cross-reacting or apparent false-negative signals. Alternatively, these seemingly aberrant signals may disclose novel variants. We report here four new HLA-B (B*5620 and B*5716) and HLA-DRB1 alleles (DRB1*110107 and DRB1*1474) that were detected by apparent false-negative or -positive hybridization or amplification patterns, and ultimately resolved by sequencing. To avoid allele misassignments, a comprehensive evaluation of acquired data as documented in a quality assurance system is therefore required to confirm unambiguous typing interpretation.

  7. Detecting false positive sequence homology: a machine learning approach.

    PubMed

    Fujimoto, M Stanley; Suvorov, Anton; Jensen, Nicholas O; Clement, Mark J; Bybee, Seth M

    2016-02-24

    Accurate detection of homologous relationships of biological sequences (DNA or amino acid) amongst organisms is an important and often difficult task that is essential to various evolutionary studies, ranging from building phylogenies to predicting functional gene annotations. There are many existing heuristic tools, most commonly based on bidirectional BLAST searches that are used to identify homologous genes and combine them into two fundamentally distinct classes: orthologs and paralogs. Due to only using heuristic filtering based on significance score cutoffs and having no cluster post-processing tools available, these methods can often produce multiple clusters constituting unrelated (non-homologous) sequences. Therefore sequencing data extracted from incomplete genome/transcriptome assemblies originated from low coverage sequencing or produced by de novo processes without a reference genome are susceptible to high false positive rates of homology detection. In this paper we develop biologically informative features that can be extracted from multiple sequence alignments of putative homologous genes (orthologs and paralogs) and further utilized in context of guided experimentation to verify false positive outcomes. We demonstrate that our machine learning method trained on both known homology clusters obtained from OrthoDB and randomly generated sequence alignments (non-homologs), successfully determines apparent false positives inferred by heuristic algorithms especially among proteomes recovered from low-coverage RNA-seq data. Almost ~42 % and ~25 % of predicted putative homologies by InParanoid and HaMStR respectively were classified as false positives on experimental data set. Our process increases the quality of output from other clustering algorithms by providing a novel post-processing method that is both fast and efficient at removing low quality clusters of putative homologous genes recovered by heuristic-based approaches.

  8. False-Positive Rate of AKI Using Consensus Creatinine-Based Criteria.

    PubMed

    Lin, Jennie; Fernandez, Hilda; Shashaty, Michael G S; Negoianu, Dan; Testani, Jeffrey M; Berns, Jeffrey S; Parikh, Chirag R; Wilson, F Perry

    2015-10-07

    Use of small changes in serum creatinine to diagnose AKI allows for earlier detection but may increase diagnostic false-positive rates because of inherent laboratory and biologic variabilities of creatinine. We examined serum creatinine measurement characteristics in a prospective observational clinical reference cohort of 2267 adult patients with AKI by Kidney Disease Improving Global Outcomes creatinine criteria and used these data to create a simulation cohort to model AKI false-positive rates. We simulated up to seven successive blood draws on an equal population of hypothetical patients with unchanging true serum creatinine values. Error terms generated from laboratory and biologic variabilities were added to each simulated patient's true serum creatinine value to obtain the simulated measured serum creatinine for each blood draw. We determined the proportion of patients who would be erroneously diagnosed with AKI by Kidney Disease Improving Global Outcomes creatinine criteria. Within the clinical cohort, 75.0% of patients received four serum creatinine draws within at least one 48-hour period during hospitalization. After four simulated creatinine measurements that accounted for laboratory variability calculated from assay characteristics and 4.4% of biologic variability determined from the clinical cohort and publicly available data, the overall false-positive rate for AKI diagnosis was 8.0% (interquartile range =7.9%-8.1%), whereas patients with true serum creatinine ≥1.5 mg/dl (representing 21% of the clinical cohort) had a false-positive AKI diagnosis rate of 30.5% (interquartile range =30.1%-30.9%) versus 2.0% (interquartile range =1.9%-2.1%) in patients with true serum creatinine values <1.5 mg/dl (P<0.001). Use of small serum creatinine changes to diagnose AKI is limited by high false-positive rates caused by inherent variability of serum creatinine at higher baseline values, potentially misclassifying patients with CKD in AKI studies. Copyright

  9. Female False Positive Exercise Stress ECG Testing - Fact Verses Fiction.

    PubMed

    Fitzgerald, Benjamin T; Scalia, William M; Scalia, Gregory M

    2018-03-07

    Exercise stress testing is a well validated cardiovascular investigation. Accuracy for treadmill stress electrocardiograph (ECG) testing has been documented at 60%. False positive stress ECGs (exercise ECG changes with non-obstructive disease on anatomical testing) are common, especially in women, limiting the effectiveness of the test. This study investigates the incidence and predictors of false positive stress ECG findings, referenced against stress echocardiography (SE) as a standard. Stress echocardiography was performed using the Bruce treadmill protocol. False positive stress ECG tests were defined as greater than 1mm of ST depression on ECG during exertion, without pain, with a normal SE. Potential causes for false positive tests were recorded before the test. Three thousand consecutive negative stress echocardiograms (1036 females, 34.5%) were analysed (age 59+/-14 years. False positive (F+) stress ECGs were documented in 565/3000 tests (18.8%). F+ stress ECGs were equally prevalent in females (194/1036, 18.7%) and males (371/1964, 18.9%, p=0.85 for the difference). Potential causes (hypertension, left ventricular hypertrophy, known coronary disease, arrhythmia, diabetes mellitus, valvular heart disease) were recorded in 36/194 (18.6%) of the female F+ ECG tests and 249/371 (68.2%) of the male F+ ECG tests (p<0.0001 for the difference). These data suggest that F+ stress ECG tests are frequent and equally common in women and men. However, most F+ stress ECGs in men can be predicted before the test, while most in women cannot. Being female may be a risk factor in itself. These data reinforce the value of stress imaging, particularly in women. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). All rights reserved.

  10. Psychological distress in U.S. women who have experienced false-positive mammograms.

    PubMed

    Jatoi, Ismail; Zhu, Kangmin; Shah, Mona; Lawrence, William

    2006-11-01

    In the United States, approximately 10.7% of all screening mammograms lead to a false-positive result, but the overall impact of false-positives on psychological well-being is poorly understood. Data were analyzed from the 2000 U.S. National Health Interview Survey (NHIS), the most recent national survey that included a cancer control module. Study subjects were 9,755 women who ever had a mammogram, of which 1,450 had experienced a false-positive result. Psychological distress was assessed using the validated K6 questionnaire and logistic regression was used to discern any association with previous false-positive mammograms. In a multivariate analysis, women who had indicated a previous false-positive mammogram were more likely to report feeling sad (OR = 1.18, 95% CI, 1.03-1.35), restless (OR = 1.23, 95% CI, 1.08-1.40), worthless (OR = 1.27, 95% CI, 1.04-1.54), and finding that everything was an effort (OR = 1.27, 95% CI, 1.10-1.47). These women were also more likely to have seen a mental health professional in the 12 months preceding the survey (OR = 1.28, 95% CI, 1.03-1.58) and had a higher composite score on all items of the K6 scale (P < 0.0001), a reflection of increased psychological distress. Analyses by age and race revealed that, among women who had experienced false-positives, younger women were more likely to feel that everything was an effort, and blacks were more likely to feel restless. In a random sampling of the U.S. population, women who had previously experienced false-positive mammograms were more likely to report symptoms of anxiety and depression.

  11. CT Colonography with Computer-aided Detection: Recognizing the Causes of False-Positive Reader Results

    PubMed Central

    Dachman, Abraham H.; Wroblewski, Kristen; Vannier, Michael W.; Horne, John M.

    2014-01-01

    Computed tomography (CT) colonography is a screening modality used to detect colonic polyps before they progress to colorectal cancer. Computer-aided detection (CAD) is designed to decrease errors of detection by finding and displaying polyp candidates for evaluation by the reader. CT colonography CAD false-positive results are common and have numerous causes. The relative frequency of CAD false-positive results and their effect on reader performance on the basis of a 19-reader, 100-case trial shows that the vast majority of CAD false-positive results were dismissed by readers. Many CAD false-positive results are easily disregarded, including those that result from coarse mucosa, reconstruction, peristalsis, motion, streak artifacts, diverticulum, rectal tubes, and lipomas. CAD false-positive results caused by haustral folds, extracolonic candidates, diminutive lesions (<6 mm), anal papillae, internal hemorrhoids, varices, extrinsic compression, and flexural pseudotumors are almost always recognized and disregarded. The ileocecal valve and tagged stool are common sources of CAD false-positive results associated with reader false-positive results. Nondismissable CAD soft-tissue polyp candidates larger than 6 mm are another common cause of reader false-positive results that may lead to further evaluation with follow-up CT colonography or optical colonoscopy. Strategies for correctly evaluating CAD polyp candidates are important to avoid pitfalls from common sources of CAD false-positive results. ©RSNA, 2014 PMID:25384290

  12. Breast cancer detection risk in screening mammography after a false-positive result.

    PubMed

    Castells, X; Román, M; Romero, A; Blanch, J; Zubizarreta, R; Ascunce, N; Salas, D; Burón, A; Sala, M

    2013-02-01

    False-positives are a major concern in breast cancer screening. However, false-positives have been little evaluated as a prognostic factor for cancer detection. Our aim was to evaluate the association of false-positive results with the cancer detection risk in subsequent screening participations over a 17-year period. This is a retrospective cohort study of 762,506 women aged 45-69 years, with at least two screening participations, who underwent 2,594,146 screening mammograms from 1990 to 2006. Multilevel discrete-time hazard models were used to estimate the adjusted odds ratios (OR) of breast cancer detection in subsequent screening participations in women with false-positive results. False-positives involving a fine-needle aspiration cytology or a biopsy had a higher cancer detection risk than those involving additional imaging procedures alone (OR = 2.69; 95%CI: 2.28-3.16 and OR = 1.81; 95%CI: 1.70-1.94, respectively). The risk of cancer detection increased substantially if women with cytology or biopsy had a familial history of breast cancer (OR = 4.64; 95%CI: 3.23-6.66). Other factors associated with an increased cancer detection risk were age 65-69 years (OR = 1.84; 95%CI: 1.67-2.03), non-attendance at the previous screening invitation (OR = 1.26; 95%CI: 1.11-1.43), and having undergone a previous benign biopsy outside the screening program (OR = 1.24; 95%CI: 1.13-1.35). Women with a false-positive test have an increased risk of cancer detection in subsequent screening participations, especially those with a false-positive result involving cytology or biopsy. Understanding the factors behind this association could provide valuable information to increase the effectiveness of breast cancer screening. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. False-positive cryptococcal antigen latex agglutination caused by disinfectants and soaps.

    PubMed Central

    Blevins, L B; Fenn, J; Segal, H; Newcomb-Gayman, P; Carroll, K C

    1995-01-01

    Five disinfectants or soaps were tested to determine if any could be responsible for false-positive results obtained with the Latex-Crypto Antigen Detection System kit (Immuno-Mycologics, Inc., Norman, Okla.). Three disinfectants or soaps (Derma soap, 7X, and Bacdown) produced false-positive agglutination after repeated washing of ring slides during testing of a known negative cerebrospinal fluid specimen. PMID:7650214

  14. Positive events protect children from causal false memories for scripted events.

    PubMed

    Melinder, Annika; Toffalini, Enrico; Geccherle, Eleonora; Cornoldi, Cesare

    2017-11-01

    Adults produce fewer inferential false memories for scripted events when their conclusions are emotionally charged than when they are neutral, but it is not clear whether the same effect is also found in children. In the present study, we examined this issue in a sample of 132 children aged 6-12 years (mean 9 years, 3 months). Participants encoded photographs depicting six script-like events that had a positively, negatively, or a neutral valenced ending. Subsequently, true and false recognition memory of photographs related to the observed scripts was tested as a function of emotionality. Causal errors-a type of false memory thought to stem from inferential processes-were found to be affected by valence: children made fewer causal errors for positive than for neutral or negative events. Hypotheses are proposed on why adults were found protected against inferential false memories not only by positive (as for children) but also by negative endings when administered similar versions of the same paradigm.

  15. Hypertension is strongly associated with false-positive bicycle exercise stress echocardiography testing results.

    PubMed

    Keller, Karsten; Stelzer, Kathrin; Munzel, Thomas; Ostad, Mir Abolfazl

    2016-12-01

    Exercise echocardiography is a reliable routine test in patients with known or suspected coronary artery disease. However, in ∼15% of all patients, stress echocardiography leads to false-positive stress echocardiography results. We aimed to investigate the impact of hypertension on stress echocardiographic results. We performed a retrospective study of patients with suspected or known stable coronary artery disease who underwent a bicycle exercise stress echocardiography. Patients with false-positive stress results were compared with those with appropriate results. 126 patients with suspected or known coronary artery disease were included in this retrospective study. 23 patients showed false-positive stress echocardiography results. Beside comparable age, gender distribution and coronary artery status, hypertension was more prevalent in patients with false-positive stress results (95.7% vs. 67.0%, p = 0.0410). Exercise peak load revealed a borderline-significance with lower loads in patients with false-positive results (100.0 (IQR 75.0/137.5) vs. 125.0 (100.0/150.0) W, p = 0.0601). Patients with false-positive stress results showed higher systolic (2.05 ± 0.69 vs. 1.67 ± 0.39 mmHg/W, p = 0.0193) and diastolic (1.03 ± 0.38 vs. 0.80 ± 0.28 mmHg/W, p = 0.0165) peak blood pressure (BP) per wattage. In a multivariate logistic regression test, hypertension (OR 17.6 [CI 95% 1.9-162.2], p = 0.0115), and systolic (OR 4.12 [1.56-10.89], p = 0.00430) and diastolic (OR 13.74 [2.46-76.83], p = 0.00285) peak BP per wattage, were associated with false-positive exercise results. ROC analysis for systolic and diastolic peak BP levels per wattage showed optimal cut-off values of 1.935mmHg/W and 0.823mmHg/W, indicating false-positive exercise echocardiographic results with AUCs of 0.660 and 0.664, respectively. Hypertension is a risk factor for false-positive stress exercise echocardiographic results in patients with known or

  16. Is there a positive bias in false recognition? Evidence from confabulating amnesia patients.

    PubMed

    Alkathiri, Nura H; Morris, Robin G; Kopelman, Michael D

    2015-10-01

    Although there is some evidence for a positive emotional bias in the content of confabulations in brain damaged patients, findings have been inconsistent. The present study used the semantic-associates procedure to induce false recall and false recognition in order to examine whether a positive bias would be found in confabulating amnesic patients, relative to non-confabulating amnesic patients and healthy controls. Lists of positive, negative and neutral words were presented in order to induce false recall or false recognition of non-presented (but semantically associated) words. The latter were termed 'critical intrusions'. Thirteen confabulating amnesic patients, 13 non-confabulating amnesic patients and 13 healthy controls were investigated. Confabulating patients falsely recognised a higher proportion of positive (but unrelated) words, compared with non-confabulating patients and healthy controls. No differences were found for recall memory. Signal detection analysis, however, indicated that the positive bias for false recognition memory might reflect weaker memory in the confabulating amnesic group. This suggested that amnesia patients with weaker memory are more likely to confabulate and the content of these confabulations are more likely to be positive. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Study of false positives in 5-ALA induced photodynamic diagnosis of bladder carcinoma

    NASA Astrophysics Data System (ADS)

    Draga, Ronald O. P.; Grimbergen, Matthijs C. M.; Kok, Esther T.; Jonges, Trudy G. N.; Bosch, J. L. H. R.

    2009-02-01

    Photodynamic diagnosis (PDD) is a technique that enhances the detection of tumors during cystoscopy using a photosensitizer which accumulates primarily in cancerous cells and will fluoresce when illuminated by violetblue light. A disadvantage of PDD is the relatively low specificity. In this retrospective study we aimed to identify predictors for false positive findings in PDD. Factors such as gender, age, recent transurethral resection of bladder tumors (TURBT), previous intravesical therapy (IVT) and urinary tract infections (UTIs) were examined for association with the false positive rates in a multivariate analysis. Data of 366 procedures and 200 patients were collected. Patients were instilled with 5-aminolevulinic acid (5-ALA) intravesically and 1253 biopsies were taken from tumors and suspicious lesions. Female gender and TURBT are independent predictors of false positives in PDD. However, previous intravesical therapy with Bacille Calmette-Guérin is also an important predictor of false positives. The false positive rate decreases during the first 9-12 weeks after the latest TURBT and the latest intravesical chemotherapy. Although shortly after IVT and TURBT false positives increase, PDD improves the diagnostic sensitivity and results in more adequate treatment strategies in a significant number of patients.

  18. Which Factors Contribute to False-Positive, False-Negative, and Invalid Results in Fetal Fibronectin Testing in Women with Symptoms of Preterm Labor?

    PubMed

    Bruijn, Merel M C; Hermans, Frederik J R; Vis, Jolande Y; Wilms, Femke F; Oudijk, Martijn A; Kwee, Anneke; Porath, Martina M; Oei, Guid; Scheepers, Hubertina C J; Spaanderman, Marc E A; Bloemenkamp, Kitty W M; Haak, Monique C; Bolte, Antoinette C; Vandenbussche, Frank P H A; Woiski, Mallory D; Bax, Caroline J; Cornette, Jérôme M J; Duvekot, Johannes J; Bijvank, Bas W A N I J; van Eyck, Jim; Franssen, Maureen T M; Sollie, Krystyna M; van der Post, Joris A M; Bossuyt, Patrick M M; Kok, Marjolein; Mol, Ben W J; van Baaren, Gert-Jan

    2017-02-01

    Objective  We assessed the influence of external factors on false-positive, false-negative, and invalid fibronectin results in the prediction of spontaneous delivery within 7 days. Methods  We studied symptomatic women between 24 and 34 weeks' gestational age. We performed uni- and multivariable logistic regression to estimate the effect of external factors (vaginal soap, digital examination, transvaginal sonography, sexual intercourse, vaginal bleeding) on the risk of false-positive, false-negative, and invalid results, using spontaneous delivery within 7 days as the outcome. Results  Out of 708 women, 237 (33%) had a false-positive result; none of the factors showed a significant association. Vaginal bleeding increased the proportion of positive fetal fibronectin (fFN) results, but was significantly associated with a lower risk of false-positive test results (odds ratio [OR], 0.22; 95% confidence intervals [CI], 0.12-0.39). Ten women (1%) had a false-negative result. None of the investigated factors was significantly associated with a significantly higher risk of false-negative results. Twenty-one tests (3%) were invalid; only vaginal bleeding showed a significant association (OR, 4.5; 95% CI, 1.7-12). Conclusion  The effect of external factors on the performance of qualitative fFN testing is limited, with vaginal bleeding as the only factor that reduces its validity. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  19. Do positive schizotypal symptoms predict false perceptual experiences in nonclinical populations?

    PubMed

    Tsakanikos, Elias; Reed, Phil

    2005-12-01

    We examined whether positive schizotypy (i.e., reports of hallucinatory and delusional-like experiences) in nonclinical participants could predict false perceptual experiences during detection of fast-moving words beyond a possible response bias. The participants (N = 160) were assigned to one of two conditions: they were asked either to make presence/absence judgments (loose criterion) or to read aloud every detected word (strict criterion). Regression analysis showed that high levels of positive schizotypy predicted false alarms in the loose condition and false perceptions of words in the strict condition. The obtained effects were independent of detection accuracy, task order, impulsivity, and social desirability. We discuss the results in the context of information processing biases linked to the positive symptomatology of schizophrenia. Clinical and theoretical implications are also considered.

  20. Response time as a discriminator between true- and false-positive responses in suprathreshold perimetry.

    PubMed

    Artes, Paul H; McLeod, David; Henson, David B

    2002-01-01

    To report on differences between the latency distributions of responses to stimuli and to false-positive catch trials in suprathreshold perimetry. To describe an algorithm for defining response time windows and to report on its performance in discriminating between true- and false-positive responses on the basis of response time (RT). A sample of 435 largely inexperienced patients underwent suprathreshold visual field examination on a perimeter that was modified to record RTs. Data were analyzed from 60,500 responses to suprathreshold stimuli and from 523 false-positive responses to catch trials. False-positive responses had much more variable latencies than responses to suprathreshold stimuli. An algorithm defining RT windows on the basis of z-transformed individual latency samples correctly identified more than 70% of false-positive responses to catch trials, whereas fewer than 3% of responses to suprathreshold stimuli were classified as false-positive responses. Latency analysis can be used to detect a substantial proportion of false-positive responses in suprathreshold perimetry. Rejection of such responses may increase the reliability of visual field screening by reducing variability and bias in a small but clinically important proportion of patients.

  1. A crisis of visibility: The psychological consequences of false-positive screening mammograms, an interview study.

    PubMed

    Bond, Mary; Garside, Ruth; Hyde, Christopher

    2015-11-01

    To understand the meaning of having a false-positive screening mammogram. Qualitative interview study. Twenty-one women, who had experienced false-positive screening mammograms, took part in semi-structured interviews that were analysed with Interpretive Phenomenological Analysis. This research took place in the United Kingdom. The analysis revealed a wide range of response to having a false-positive mammogram, from nonchalance to extreme fear. These reactions come from the potential for the belief that one is healthy to be challenged by being recalled, as the worst is frequently assumed. For most, the image of the lesion on the X-ray brought the reality of this challenge into sharp focus, as they might soon discover they had breast cancer. Waiting, whether for the appointment, at the clinic or for biopsy results was considered the worst aspect of being recalled. Generally, the uncertainty was quickly resolved with the pronouncement of the 'all-clear', which brought considerable relief and the restoration of belief in the healthy self. However, for some, lack of information, contradictory information, or poor interpersonal communication meant that uncertainty about their health status lingered at least until their next normal screening mammogram. Mammography screening related anxiety lasted for up to 12 years. Breast cancer screening produces a 'crisis of visibility'. Accepting the screening invitation is taking a risk that you may experience unnecessary stress, uncertainty, fear, anxiety, and physical pain. Not accepting the invitation is taking a risk that malignant disease will remain invisible. Statement of contribution What is already known on this subject? More than 50,000 women a year in England have a false-positive mammogram (FPM). Having an FPM can cause anxiety compared with a normal mammogram. The anxiety can last up to 35 months. What does this study add? Refocuses attention from the average response found in quantitative studies to the wide range of

  2. False-positive cerebrospinal fluid cryptococcus antigen in Libman-Sacks endocarditis.

    PubMed

    Isseh, Iyad N; Bourgi, Kassem; Nakhle, Asaad; Ali, Mahmoud; Zervos, Marcus J

    2016-12-01

    Cryptococcus meningoencephalitis is a serious opportunistic infection associated with high morbidity and mortality in immunocompromised hosts, particularly patients with advanced AIDS disease. The diagnosis is established through cerebrospinal fluid (CSF) cryptococcus antigen detection and cultures. Cryptococcus antigen testing is usually the initial test of choice due its high sensitivity and specificity along with the quick availability of the results. We hereby report a case of a false-positive CSF cryptococcus antigen assay in a patient with systemic lupus erythematosus presenting with acute confusion. While initial CSF evaluation revealed a positive cryptococcus antigen assay, the patient's symptoms were inconsistent with cryptococcus meningoencephalitis. A repeat CSF evaluation, done 3 days later, revealed a negative CSF cryptococcus antigen assay. Given the patient's active lupus disease and the elevated antinuclear antibody titers, we believe that the initial positive result was a false positive caused by interference from autoantibodies.

  3. Skin irritation, false positives and the local lymph node assay: a guideline issue?

    PubMed

    Basketter, David A; Kimber, Ian

    2011-10-01

    Since the formal validation and regulatory acceptance of the local lymph node assay (LLNA) there have been commentaries suggesting that the irritant properties of substances can give rise to false positives. As toxicology aspires to progress rapidly towards the age of in vitro alternatives, it is of increasing importance that issues relating to assay selectivity and performance are understood fully, and that true false positive responses are distinguished clearly from those that are simply unpalatable. In the present review, we have focused on whether skin irritation per se is actually a direct cause of true false positive results in the LLNA. The body of published work has been examined critically and considered in relation to our current understanding of the mechanisms of skin irritation and skin sensitisation. From these analyses it is very clear that, of itself, skin irritation is not a cause of false positive results. The corollary is, therefore, that limiting test concentrations in the LLNA for the purpose of avoiding skin irritation may lead, unintentionally, to false negatives. Where a substance is a true false positive in the LLNA, the classic example being sodium lauryl sulphate, explanations for that positivity will have to reach beyond the seductive, but incorrect, recourse to its skin irritation potential. Copyright © 2011 Elsevier Inc. All rights reserved.

  4. Evaluation of positive and false-positive results in syphilis screening of blood donors in Rio de Janeiro, Brazil.

    PubMed

    Sandes, V S; Silva, S G C; Motta, I J F; Velarde, L G C; de Castilho, S R

    2017-06-01

    We propose to analyse the positive and false-positive results of treponemal and nontreponemal tests in blood donors from Brazil and to evaluate possible factors associated with the results of treponemal tests. Treponemal tests have been used widely for syphilis screening in blood banks. The introduction of these tests in donor screening has caused an impact and a loss of donors who need to be assessed. This was a retrospective cross-sectional study of syphilis screening and confirmatory test results of blood donors that were obtained before and after adopting a chemiluminescent immunoassay (CLIA). A comparative analysis was performed using a second sample drawn from positive donors. The possible factors associated with CLIA-positive or CLIA-false-positive results were investigated in a subgroup. Statistical tests were used to compare the proportions and adjusted estimates of association. The reactivity rate increased from 1·01% (N = 28 158) to 2·66% (N = 25 577) after introducing the new test. Among Venereal Disease Research Laboratory (VDRL)- and CLIA-confirmed results, the false-positive rates were 40·5% (N = 180) and 37·4% (N = 359), respectively (P = 0·5266). Older donors (OR = 1·04; P = 0·0010) and donors with lower education levels (OR = 6·59; P = 0·0029) were associated with a higher risk of positivity for syphilis. CLIA represents an improvement in blood bank serological screening. However, its use in a healthy population appears to result in high rates of false positives. Identifying which characteristics can predict false positives, however, remains a challenge. © 2017 British Blood Transfusion Society.

  5. Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mordang, Jan-Jurre, E-mail: Jan-Jurre.Mordang@radboudumc.nl; Gubern-Mérida, Albert; Karssemeijer, Nico

    Purpose: In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists’ detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performancemore » of the CADe system in finding malignant microcalcifications. Methods: A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. Results: The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the

  6. Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications.

    PubMed

    Mordang, Jan-Jurre; Gubern-Mérida, Albert; den Heeten, Gerard; Karssemeijer, Nico

    2016-04-01

    In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists' detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performance of the CADe system in finding malignant microcalcifications. A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity range of 0.8-1.0 were

  7. Cumulative Incidence of False-Positive Results in Repeated, Multimodal Cancer Screening

    PubMed Central

    Croswell, Jennifer Miller; Kramer, Barnett S.; Kreimer, Aimee R.; Prorok, Phil C.; Xu, Jian-Lun; Baker, Stuart G.; Fagerstrom, Richard; Riley, Thomas L.; Clapp, Jonathan D.; Berg, Christine D.; Gohagan, John K.; Andriole, Gerald L.; Chia, David; Church, Timothy R.; Crawford, E. David; Fouad, Mona N.; Gelmann, Edward P.; Lamerato, Lois; Reding, Douglas J.; Schoen, Robert E.

    2009-01-01

    PURPOSE Multiple cancer screening tests have been advocated for the general population; however, clinicians and patients are not always well-informed of screening burdens. We sought to determine the cumulative risk of a false-positive screening result and the resulting risk of a diagnostic procedure for an individual participating in a multimodal cancer screening program. METHODS Data were analyzed from the intervention arm of the ongoing Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, a randomized controlled trial to determine the effects of prostate, lung, colorectal, and ovarian cancer screening on disease-specific mortality. The 68,436 participants, aged 55 to 74 years, were randomized to screening or usual care. Women received serial serum tests to detect cancer antigen 125 (CA-125), transvaginal sonograms, posteroanterior-view chest radiographs, and flexible sigmoidoscopies. Men received serial chest radiographs, flexible sigmoidoscopies, digital rectal examinations, and serum prostate-specific antigen tests. Fourteen screening examinations for each sex were possible during the 3-year screening period. RESULTS After 14 tests, the cumulative risk of having at least 1 false-positive screening test is 60.4% (95% CI, 59.8%–61.0%) for men, and 48.8% (95% CI, 48.1%–49.4%) for women. The cumulative risk after 14 tests of undergoing an invasive diagnostic procedure prompted by a false-positive test is 28.5% (CI, 27.8%–29.3%) for men and 22.1% (95% CI, 21.4%–22.7%) for women. CONCLUSIONS For an individual in a multimodal cancer screening trial, the risk of a false-positive finding is about 50% or greater by the 14th test. Physicians should educate patients about the likelihood of false positives and resulting diagnostic interventions when counseling about cancer screening. PMID:19433838

  8. Memory for media: investigation of false memories for negatively and positively charged public events.

    PubMed

    Porter, Stephen; Taylor, Kristian; Ten Brinke, Leanne

    2008-01-01

    Despite a large body of false memory research, little has addressed the potential influence of an event's emotional content on susceptibility to false recollections. The Paradoxical Negative Emotion (PNE) hypothesis predicts that negative emotion generally facilitates memory but also heightens susceptibility to false memories. Participants were asked whether they could recall 20 "widely publicised" public events (half fictitious) ranging in emotional valence, with or without visual cues. Participants recalled a greater number of true negative events (M=3.31/5) than true positive (M=2.61/5) events. Nearly everyone (95%) came to recall at least one false event (M=2.15 false events recalled). Further, more than twice as many participants recalled any false negative (90%) compared to false positive (41.7%) events. Negative events, in general, were associated with more detailed memories and false negative event memories were more detailed than false positive event memories. Higher dissociation scores were associated with false recollections of negative events, specifically.

  9. False positive computed tomographic angiography for Stanford type A aortic dissection.

    PubMed

    Bandali, Murad F; Hatem, Muhammed A; Appoo, Jehangir J; Hutchison, Stuart J; Wong, Jason K

    2015-12-01

    Computed tomographic angiography (CTA) has emerged as the defacto imaging test to rule out acute aortic dissection; however, it is not without flaws. We report a case of a false-positive CTA with respect to Stanford Type A aortic dissection. A 52 year-old male presented with sudden onset shortness of breath. He denied chest pain. Due to severe hypertension and an Emergency Department bedside ultrasound suggesting an intimal flap in the aorta, CTA was requested to better assess the ascending aorta and was interpreted as consistent with Stanford Type A aortic dissection with thrombosis of the false lumen in the ascending aorta. However, intra-operative imaging (TEE and epi-aortic scanning) did not identify an intimal flap or dissection, and neither did definitive surgical inspection of the aorta. The suspected aortic dissection and thrombosed false lumen were not visualized on repeat CTA two days later. False positive diagnosis of Stanford Type A aortic dissection on CTA can be the result of technical factors, streak artifacts, motion artifacts, and periaortic structures. In this case, non-uniform arterial contrast enhancement secondary to unrecognized biventricular dysfunction resulted in the false positive CTA appearance of an intimal flap and mural thrombus. Intra-operative TEE and epi-aortic scanning were proven correct in excluding aortic dissection by the standard of definitive surgical inspection of the aorta.

  10. The epidemiology of pertussis in the Australian Capital Territory, 1999 to 2005--epidemics of testing, disease or false positives?

    PubMed

    Wylks, Clare E; Ewald, Ben; Guest, Charles

    2007-12-01

    The increase in pertussis notifications since the 1990s in many countries, including Australia, has been attributed to improved diagnosis. This study aimed to describe the epidemiology of pertussis in the Australian Capital Territory from 1999 to 2005, determine whether the apparent changes could be accounted for by greater recognition and testing, and explore the impact of false positive serology results associated with faulty test kits. The Australian Capital Territory resident notification, laboratory and separation data from 1999 to 2005 were examined and the proportions of positive tests across time periods and age groups compared. Notification rates increased in the years 2000, 2003 and 2005. There was a shift in the age distribution of cases, from children and teenagers in 2000, to teenagers in 2003 and adults in 2005. Testing activity and notification activity were closely related. Comparing the epidemic periods to the preceding inter-epidemic periods, the proportion of positive tests was maintained or increased for all age groups combined and for adults and children (e.g. statistically significant increase from 7.8% to 14.0% in the 2005 epidemic in adults). During each epidemic the proportion of positive tests was statistically significantly higher in the age group with the highest notification activity. Despite similar testing rates in adults in 2003 and 2005, greater disease activity was reported in 2005. Although the numbers were small, polymerase chain reaction and culture positive test results increased in 2003 but not in 2005. The proportion of positive polymerase chain reaction results increased in 2003, providing strong evidence that the apparent epidemic of 2003 was due to a true increase in underlying disease activity. Because of the uncertainty surrounding the timing of the false positive serology results, the study provides weaker support for a true epidemic of pertussis in 2005.

  11. False Positivity of Non-Targeted Infections in Malaria Rapid Diagnostic Tests: The Case of Human African Trypanosomiasis

    PubMed Central

    Gillet, Philippe; Mumba Ngoyi, Dieudonné; Lukuka, Albert; Kande, Viktor; Atua, Benjamin; van Griensven, Johan; Muyembe, Jean-Jacques; Jacobs, Jan; Lejon, Veerle

    2013-01-01

    Background In endemic settings, diagnosis of malaria increasingly relies on the use of rapid diagnostic tests (RDTs). False positivity of such RDTs is poorly documented, although it is especially relevant in those infections that resemble malaria, such as human African trypanosomiasis (HAT). We therefore examined specificity of malaria RDT products among patients infected with Trypanosoma brucei gambiense. Methodology/Principal Findings Blood samples of 117 HAT patients and 117 matched non-HAT controls were prospectively collected in the Democratic Republic of the Congo. Reference malaria diagnosis was based on real-time PCR. Ten commonly used malaria RDT products were assessed including three two-band and seven three-band products, targeting HRP-2, Pf-pLDH and/or pan-pLDH antigens. Rheumatoid factor was determined in PCR negative subjects. Specificity of the 10 malaria RDT products varied between 79.5 and 100% in HAT-negative controls and between 11.3 and 98.8% in HAT patients. For seven RDT products, specificity was significantly lower in HAT patients compared to controls. False positive reactions in HAT were mainly observed for pan-pLDH test lines (specificities between 13.8 and 97.5%), but also occurred frequently for the HRP-2 test line (specificities between 67.9 and 98.8%). The Pf-pLDH test line was not affected by false-positive lines in HAT patients (specificities between 97.5 and 100%). False positivity was not associated to rheumatoid factor, detected in 7.6% of controls and 1.2% of HAT patients. Conclusions/Significance Specificity of some malaria RDT products in HAT was surprisingly low, and constitutes a risk for misdiagnosis of a fatal but treatable infection. Our results show the importance to assess RDT specificity in non-targeted infections when evaluating diagnostic tests. PMID:23638201

  12. The risk factor of false-negative and false-positive for T-SPOT.TB in active tuberculosis.

    PubMed

    Di, Li; Li, Yan

    2018-02-01

    T-SPOT.TB is a promising diagnosis tool to identify both pulmonary tuberculosis and extrapulmonary tuberculosis, as well as latent tuberculosis; however, the factors that affect the results of T-SPOT.TB remains unclear. In this study, we aim to figure out the risk factor of T-SPOT.TB for active TB. A total of 349 patients were recruited between January 1st, 2016 and January 22st, 2017 at Renmin Hospital of Wuhan University, including 98 subjects with TB and 251 subjects with non-TB disease, and received T-SPOT.TB (Oxford Immunotec Ltd). Statistics were analyzed by SPSS 19.0 using logistic regression. The overall specificity and sensitivity of the T-SPOT.TB was 92.83% (233/251; 95%CI 0.8872-0.9557) and 83.67% (82/98; 95%CI 0.7454-0.9010), respectively. Patients with tuberculous meningitis were more likely to have false-negative results (OR 17.4, 95%CI 3.068-98.671; P<.001) while patients with cured TB tended to induce false-positive results (OR 30.297; 95%CI 7.069-129.849; P<.001). The results were not affected by sex, age, onset time, smoke, alcohol, treatment, allergic history, co-morbidity, TB (exclude tuberculous meningitis) (P>.05). Tuberculous meningitis was a risk factor of false-negative for T-SPOT.TB, while cured TB was a risk factor of false-positive. © 2017 Wiley Periodicals, Inc.

  13. Algorithm of reducing the false positives in IDS based on correlation Analysis

    NASA Astrophysics Data System (ADS)

    Liu, Jianyi; Li, Sida; Zhang, Ru

    2018-03-01

    This paper proposes an algorithm of reducing the false positives in IDS based on correlation Analysis. Firstly, the algorithm analyzes the distinguishing characteristics of false positives and real alarms, and preliminary screen the false positives; then use the method of attribute similarity clustering to the alarms and further reduces the amount of alarms; finally, according to the characteristics of multi-step attack, associated it by the causal relationship. The paper also proposed a reverse causation algorithm based on the attack association method proposed by the predecessors, turning alarm information into a complete attack path. Experiments show that the algorithm simplifies the number of alarms, improve the efficiency of alarm processing, and contribute to attack purposes identification and alarm accuracy improvement.

  14. Gas insufflation of minimal preparation CT of the colon reduces false-positives

    PubMed Central

    Slater, A; North, M; Hart, M; Ferrett, C

    2012-01-01

    Objectives Minimal preparation CT of the colon (MPCT colon) is used for investigation of suspected colorectal cancer in frail and/or elderly patients who would be expected to tolerate laxative bowel preparation poorly. Although it has good sensitivity for colorectal cancer it has a poor specificity. We wished to investigate whether distension of the colon with carbon dioxide alone would reduce the number of false-positives, but without making the test arduous or excessively uncomfortable. Methods 134 patients were recruited and underwent MPCT colon with gas insufflation and antispasmodics. Results were compared with a cohort of 134 patients undergoing standard protocol MPCT colon. The numbers of false-positives were compared, as was reader confidence. All trial patients were given a questionnaire documenting their experience. Results The number of false-positives was 15% in the control group and 5% in the trial group; this difference was statistically significant, (p=0.01). Reader confidence was increased in the trial group. Patient tolerance was good, with 95% saying they would have the test again. Conclusion Use of gas insufflation and antispasmodics reduces the false-positives from 15% to 5% without adversely affecting patient tolerance. PMID:21224295

  15. Sherlock Holmes and child psychopathology assessment approaches: the case of the false-positive.

    PubMed

    Jensen, P S; Watanabe, H

    1999-02-01

    To explore the relative value of various methods of assessing childhood psychopathology, the authors compared 4 groups of children: those who met criteria for one or more DSM diagnoses and scored high on parent symptom checklists, those who met psychopathology criteria on either one of these two assessment approaches alone, and those who met no psychopathology assessment criterion. Parents of 201 children completed the Child Behavior Checklist (CBCL), after which children and parents were administered the Diagnostic Interview Schedule for Children (version 2.1). Children and parents also completed other survey measures and symptom report inventories. The 4 groups of children were compared against "external validators" to examine the merits of "false-positive" and "false-negative" cases. True-positive cases (those that met DSM criteria and scored high on the CBCL) differed significantly from the true-negative cases on most external validators. "False-positive" and "false-negative" cases had intermediate levels of most risk factors and external validators. "False-positive" cases were not normal per se because they scored significantly above the true-negative group on a number of risk factors and external validators. A similar but less marked pattern was noted for "false-negatives." Findings call into question whether cases with high symptom checklist scores despite no formal diagnoses should be considered "false-positive." Pending the availability of robust markers for mental illness, researchers and clinicians must resist the tendency to reify diagnostic categories or to engage in arcane debates about the superiority of one assessment approach over another.

  16. False positive acetaminophen concentrations in patients with liver injury.

    PubMed

    Polson, Julie; Wians, Frank H; Orsulak, Paul; Fuller, Dwain; Murray, Natalie G; Koff, Jonathan M; Khan, Adil I; Balko, Jody A; Hynan, Linda S; Lee, William M

    2008-05-01

    Acetaminophen toxicity is the most common form of acute liver failure in the U.S. After acetaminophen overdoses, quantitation of plasma acetaminophen can aid in predicting severity of injury. However, recent case reports have suggested that acetaminophen concentrations may be falsely increased in the presence of hyperbilirubinemia. We tested sera obtained from 43 patients with acute liver failure, mostly unrelated to acetaminophen, utilizing 6 different acetaminophen quantitation systems to determine the significance of this effect. In 36 of the 43 samples with bilirubin concentrations ranging from 1.0-61.5 mg/dl no acetaminophen was detectable by gas chromatography-mass spectroscopy. These 36 samples were then utilized to test the performance characteristics of 2 immunoassay and 4 enzymatic-colorimetric methods. Three of four colorimetric methods demonstrated 'detectable' values for acetaminophen in from 4 to 27 of the 36 negative samples, low concentration positive values being observed when serum bilirubin concentrations exceeded 10 mg/dl. By contrast, the 2 immunoassay methods (EMIT, FPIA) were virtually unaffected. The false positive values obtained were, in general, proportional to the quantity of bilirubin in the sample. However, prepared samples of normal human serum with added bilirubin showed a dose-response curve for only one of the 4 colorimetric assays. False positive acetaminophen tests may result when enzymatic-colorimetric assays are used, most commonly with bilirubin concentrations >10 mg/dl, leading to potential clinical errors in this setting. Bilirubin (or possibly other substances in acute liver failure sera) appears to affect the reliable measurement of acetaminophen, particularly with enzymatic-colorimetric assays.

  17. Improving computer-aided detection assistance in breast cancer screening by removal of obviously false-positive findings.

    PubMed

    Mordang, Jan-Jurre; Gubern-Mérida, Albert; Bria, Alessandro; Tortorella, Francesco; den Heeten, Gerard; Karssemeijer, Nico

    2017-04-01

    Computer-aided detection (CADe) systems for mammography screening still mark many false positives. This can cause radiologists to lose confidence in CADe, especially when many false positives are obviously not suspicious to them. In this study, we focus on obvious false positives generated by microcalcification detection algorithms. We aim at reducing the number of obvious false-positive findings by adding an additional step in the detection method. In this step, a multiclass machine learning method is implemented in which dedicated classifiers learn to recognize the patterns of obvious false-positive subtypes that occur most frequently. The method is compared to a conventional two-class approach, where all false-positive subtypes are grouped together in one class, and to the baseline CADe system without the new false-positive removal step. The methods are evaluated on an independent dataset containing 1,542 screening examinations of which 80 examinations contain malignant microcalcifications. Analysis showed that the multiclass approach yielded a significantly higher sensitivity compared to the other two methods (P < 0.0002). At one obvious false positive per 100 images, the baseline CADe system detected 61% of the malignant examinations, while the systems with the two-class and multiclass false-positive reduction step detected 73% and 83%, respectively. Our study showed that by adding the proposed method to a CADe system, the number of obvious false positives can decrease significantly (P < 0.0002). © 2017 American Association of Physicists in Medicine.

  18. An immunoblotting diagnostic assay for heartwater based on the immunodominant 32-kilodalton protein of Cowdria ruminantium detects false positives in field sera.

    PubMed Central

    Mahan, S M; Tebele, N; Mukwedeya, D; Semu, S; Nyathi, C B; Wassink, L A; Kelly, P J; Peter, T; Barbet, A F

    1993-01-01

    Heartwater, a major constraint to improved livestock production in Zimbabwe, threatens to invade areas which have been previously unaffected. To monitor its spread in Zimbabwe, an immunoblotting diagnostic assay based on the responses of animals to the immunodominant, conserved 32-kDa protein of Cowdria ruminantium was evaluated. In this assay, no false reactions were detected with sera known to be positive and negative, but sera from some cattle, sheep, and goats from heartwater-free areas of Zimbabwe reacted strongly with the 32-kDa protein, suggesting that either these animals had previous exposure to heartwater or they were false positives. To investigate the possibility of previous exposure to heartwater, 11 immunoblot-positive and 6 immunoblot-negative sheep from heartwater-free areas of Zimbabwe were compared regarding their susceptibilities to challenge with C. ruminantium. Prior to challenge, C. ruminantium could not be detected in any sheep by transmission to Amblyomma hebraeum ticks or by the polymerase chain reaction (PCR) conducted with plasma samples. All sheep were equally susceptible to the challenge, and infection was confirmed by brain biopsy, necropsy, PCR, and transmission of C. ruminantium to ticks. Our data suggest that the immunoblot-positive reactions of sera from heartwater-free areas were due not to previous C. ruminantium infection but rather to antigenic cross-reactivity between C. ruminantium and another agent(s) such as Ehrlichia species. In conclusion, the immunodominant 32-kDa protein is not antigenically specific to C. ruminantium and its use in serological diagnosis of heartwater requires reevaluation. Images PMID:8253974

  19. Looking for Childhood Schizophrenia: Case Series of False Positives.

    ERIC Educational Resources Information Center

    Stayer, Catherine; Sporn, Alexandra; Gogtay, Nitin; Tossell, Julia; Lenane, Marge; Gochman, Peter; Rapoport, Judith L.

    2004-01-01

    Extensive experience with the diagnosis of childhood-onset schizophrenia indicates a high rate of false positives. Most mislabeled patients have chronic disabling, affective, or behavioral disorders. The authors report the cases of three children who passed stringent initial childhood-onset schizophrenia "screens" but had no chronic psychotic…

  20. Analyzing false positives of four questions in the Force Concept Inventory

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun-ichiro; Mae, Naohiro; Hull, Michael M.; Taniguchi, Masa-aki

    2018-06-01

    In this study, we analyze the systematic error from false positives of the Force Concept Inventory (FCI). We compare the systematic errors of question 6 (Q.6), Q.7, and Q.16, for which clearly erroneous reasoning has been found, with Q.5, for which clearly erroneous reasoning has not been found. We determine whether or not a correct response to a given FCI question is a false positive using subquestions. In addition to the 30 original questions, subquestions were introduced for Q.5, Q.6, Q.7, and Q.16. This modified version of the FCI was administered to 1145 university students in Japan from 2015 to 2017. In this paper, we discuss our finding that the systematic errors of Q.6, Q.7, and Q.16 are much larger than that of Q.5 for students with mid-level FCI scores. Furthermore, we find that, averaged over the data sample, the sum of the false positives from Q.5, Q.6, Q.7, and Q.16 is about 10% of the FCI score of a midlevel student.

  1. Case Reports of Aripiprazole Causing False-Positive Urine Amphetamine Drug Screens in Children.

    PubMed

    Kaplan, Justin; Shah, Pooja; Faley, Brian; Siegel, Mark E

    2015-12-01

    Urine drug screens (UDSs) are used to identify the presence of certain medications. One limitation of UDSs is the potential for false-positive results caused by cross-reactivity with other substances. Amphetamines have an extensive list of cross-reacting medications. The literature contains reports of false-positive amphetamine UDSs with multiple antidepressants and antipsychotics. We present 2 cases of presumed false-positive UDSs for amphetamines after ingestion of aripiprazole. Case 1 was a 16-month-old girl who accidently ingested 15 to 45 mg of aripiprazole. She was lethargic and ataxic at home with 1 episode of vomiting containing no identifiable tablets. She remained sluggish with periods of irritability and was admitted for observation. UDS on 2 consecutive days came back positive for amphetamines. Case 2 was of a 20-month-old girl who was brought into the hospital after accidental ingestion of an unknown quantity of her father's medications which included aripiprazole. UDS on the first day of admission came back positive only for amphetamines. Confirmatory testing with gas chromatography-mass spectrometry (GC-MS) on the blood and urine samples were also performed for both patients on presentation to detect amphetamines and were subsequently negative. Both patients returned to baseline and were discharged from the hospital. To our knowledge, these cases represent the first reports of false-positive amphetamine urine drug tests with aripiprazole. In both cases, aripiprazole was the drug with the highest likelihood of causing the positive amphetamine screen. The implications of these false-positives include the possibility of unnecessary treatment and monitoring of patients. Copyright © 2015 by the American Academy of Pediatrics.

  2. Streptomycin interference in Jaffe reaction - possible false positive creatinine estimation in excessive dose exposure.

    PubMed

    Syal, Kirtimaan; Srinivasan, Anand; Banerjee, Dibyajyoti

    2013-01-01

    To study the potential of commonly used aminoglycoside antibiotics to form non-creatinine chromogen with alkaline picrate reagent. We studied the non-creatinine chromogen formation of various concentrations of streptomycin, amikacin, kanamycin, netilmicin, gentamicin and tobramycin added to known creatinine concentrations by the Jaffe reaction based creatinine estimation. Only streptomycin above therapeutic concentrations of 10mg/mL interfered in the Jaffe reaction and acted as non-creatinine chromogen. Therapeutic doses of the aminoglycosides do not form non-creatinine chromogens. Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  3. Evaluation of inadequate, indeterminate, false-negative and false-positive cases in cytological examination for breast cancer according to histological type

    PubMed Central

    2012-01-01

    Background We previously investigated the current status of breast cytology cancer screening at seven institutes in our area of southern Fukuoka Prefecture, and found some differences in diagnostic accuracy among the institutions. In the present study, we evaluated the cases involved and noted possible reasons for their original cytological classification as inadequate, indeterminate, false-negative and false-positive according to histological type. Methods We evaluated the histological findings in 5693 individuals who underwent cytological examination for breast cancer (including inadequate, indeterminate, false-negative and false-positive cases), to determine the most common histological types and/or features in these settings and the usefulness/limitations of cytological examination for the diagnosis of breast cancer. Results Among 1152 cytologically inadequate cases, histology revealed that 75/173 (43.6%) cases were benign, including mastopathy (fibrocystic disease) in 38.6%, fibroadenoma in 24.0% and papilloma in 5.3%. Ninety-five of 173 (54.9%) cases were histologically malignant, with scirrhous growing type, invasive ductal carcinoma (SIDC) being significantly more frequent (49.5%) than papillotubular growing type (Papi-tub) (P < 0.0001), solid-tubular growing type (P = 0.0001) and ductal carcinoma in situ (DCIS) (P = 0.0001). Among 458 indeterminate cases, 54/139 (38.8%) were histologically benign (mastopathy, 30.0%; fibroadenoma, 27.8%; papilloma, 26.0%) and 73/139 (52.5%) were malignant, with SIDC being the most frequent malignant tumor (37.0%). Among 52 false-negative cases, SIDC was significantly more frequent (42.3%) than DCIS (P = 0.0049) and Papi-tub (P = 0.001). There were three false-positive cases, with one each of fibroadenoma, epidermal cyst and papilloma. Conclusions The inadequate, indeterminate, false-negative and false-positive cases showed similar histological types, notably SIDC for malignant tumors, and mastopathy

  4. Automatic lung nodule graph cuts segmentation with deep learning false positive reduction

    NASA Astrophysics Data System (ADS)

    Sun, Wenqing; Huang, Xia; Tseng, Tzu-Liang Bill; Qian, Wei

    2017-03-01

    To automatic detect lung nodules from CT images, we designed a two stage computer aided detection (CAD) system. The first stage is graph cuts segmentation to identify and segment the nodule candidates, and the second stage is convolutional neural network for false positive reduction. The dataset contains 595 CT cases randomly selected from Lung Image Database Consortium and Image Database Resource Initiative (LIDC/IDRI) and the 305 pulmonary nodules achieved diagnosis consensus by all four experienced radiologists were our detection targets. Consider each slice as an individual sample, 2844 nodules were included in our database. The graph cuts segmentation was conducted in a two-dimension manner, 2733 lung nodule ROIs are successfully identified and segmented. With a false positive reduction by a seven-layer convolutional neural network, 2535 nodules remain detected while the false positive dropped to 31.6%. The average F-measure of segmented lung nodule tissue is 0.8501.

  5. False-positive ethyl glucuronide immunoassay screening caused by a propyl alcohol-based hand sanitizer.

    PubMed

    Arndt, Torsten; Grüner, Joachim; Schröfel, Stefanie; Stemmerich, Karsten

    2012-11-30

    Urine ethyl glucuronide (EtG) is considered as a specific marker of recent ethanol consumption. We describe false-positive DRI(®) EIA EtG enzyme immunoassay results caused by propyl glucuronides in urine after using a propanol-based hand sanitizer. EtG screening was done with the DRI(®) EIA EtG assay (Microgenics), using a cut-off of 0.5 mg/L as recommended by the manufacturer and of 0.1 mg/L as demanded by the German Regulations for Reissuing Drivers Licenses. Confirmatory EtG analysis was done with the ClinMass(®) EtG LC-MS/MS testkit (Recipe), extended by the mass transitions 235.1→75.1, 235.1→85.1, and 235.1→113.1 for the detection of the 1- and 2-propyl glucuronides. Self-experiments were done by staff members of our lab (n=7), using 3 mL Sterillium(®) Classic Pure (30 g/100 g 1-propanol and 45 g/100 g 2-propanol) for hand sanitation every quarter of an hour for 8 h according to DIN EN 1500:2011-05 with and without an exhauster and by passive inhalation of the sanitizer vapor. Spot urine samples were taken immediately before and up to 24 h after the first sanitizer use. False-positive immunoassay results of up to 4 mg/L or 2.3 mg/g creatinine were obtained after normal use of the sanitizer and also after passive inhalation of the sanitizer vapor (up to 0.89 mg/L or 0.61 mg/g). Immunoassay results were positive even after 4-fold use of the sanitizer (up to 0.14 mg/L or 0.38 mg/g) and up to 6 h after the last sanitizer contact (maximum 0.63 mg/L and 0.33 mg/g for sanitizer users and 0.25 mg/g after passive inhalation). Spiking of EtG-free urine with 1-propyl glucuronide (Athena Environmental Sciences) between 0.05 and 10 mg/L clearly demonstrated a cross reaction of the immunoassay of approx. 10% as compared to EtG. LC-MS/MS of urines with a positive immunoassay EtG result did not show EtG signals, but distinct signals of 1-propyl glucuronide (n-propyl glucuronide) and 2-propyl glucuronide (iso-propyl glucuronide). An exhauster effectively prevented

  6. Reducing false-positive incidental findings with ensemble genotyping and logistic regression based variant filtering methods.

    PubMed

    Hwang, Kyu-Baek; Lee, In-Hee; Park, Jin-Ho; Hambuch, Tina; Choe, Yongjoon; Kim, MinHyeok; Lee, Kyungjoon; Song, Taemin; Neu, Matthew B; Gupta, Neha; Kohane, Isaac S; Green, Robert C; Kong, Sek Won

    2014-08-01

    As whole genome sequencing (WGS) uncovers variants associated with rare and common diseases, an immediate challenge is to minimize false-positive findings due to sequencing and variant calling errors. False positives can be reduced by combining results from orthogonal sequencing methods, but costly. Here, we present variant filtering approaches using logistic regression (LR) and ensemble genotyping to minimize false positives without sacrificing sensitivity. We evaluated the methods using paired WGS datasets of an extended family prepared using two sequencing platforms and a validated set of variants in NA12878. Using LR or ensemble genotyping based filtering, false-negative rates were significantly reduced by 1.1- to 17.8-fold at the same levels of false discovery rates (5.4% for heterozygous and 4.5% for homozygous single nucleotide variants (SNVs); 30.0% for heterozygous and 18.7% for homozygous insertions; 25.2% for heterozygous and 16.6% for homozygous deletions) compared to the filtering based on genotype quality scores. Moreover, ensemble genotyping excluded > 98% (105,080 of 107,167) of false positives while retaining > 95% (897 of 937) of true positives in de novo mutation (DNM) discovery in NA12878, and performed better than a consensus method using two sequencing platforms. Our proposed methods were effective in prioritizing phenotype-associated variants, and an ensemble genotyping would be essential to minimize false-positive DNM candidates. © 2014 WILEY PERIODICALS, INC.

  7. Reducing false positive incidental findings with ensemble genotyping and logistic regression-based variant filtering methods

    PubMed Central

    Hwang, Kyu-Baek; Lee, In-Hee; Park, Jin-Ho; Hambuch, Tina; Choi, Yongjoon; Kim, MinHyeok; Lee, Kyungjoon; Song, Taemin; Neu, Matthew B.; Gupta, Neha; Kohane, Isaac S.; Green, Robert C.; Kong, Sek Won

    2014-01-01

    As whole genome sequencing (WGS) uncovers variants associated with rare and common diseases, an immediate challenge is to minimize false positive findings due to sequencing and variant calling errors. False positives can be reduced by combining results from orthogonal sequencing methods, but costly. Here we present variant filtering approaches using logistic regression (LR) and ensemble genotyping to minimize false positives without sacrificing sensitivity. We evaluated the methods using paired WGS datasets of an extended family prepared using two sequencing platforms and a validated set of variants in NA12878. Using LR or ensemble genotyping based filtering, false negative rates were significantly reduced by 1.1- to 17.8-fold at the same levels of false discovery rates (5.4% for heterozygous and 4.5% for homozygous SNVs; 30.0% for heterozygous and 18.7% for homozygous insertions; 25.2% for heterozygous and 16.6% for homozygous deletions) compared to the filtering based on genotype quality scores. Moreover, ensemble genotyping excluded > 98% (105,080 of 107,167) of false positives while retaining > 95% (897 of 937) of true positives in de novo mutation (DNM) discovery, and performed better than a consensus method using two sequencing platforms. Our proposed methods were effective in prioritizing phenotype-associated variants, and ensemble genotyping would be essential to minimize false positive DNM candidates. PMID:24829188

  8. Prescription drugs associated with false-positive results when using faecal immunochemical tests for colorectal cancer screening.

    PubMed

    Ibáñez-Sanz, Gemma; Garcia, Montse; Rodríguez-Moranta, Francisco; Binefa, Gemma; Gómez-Matas, Javier; Domènech, Xènia; Vidal, Carmen; Soriano, Antonio; Moreno, Víctor

    2016-10-01

    The most common side effect in population screening programmes is a false-positive result which leads to unnecessary risks and costs. To identify factors associated with false-positive results in a colorectal cancer screening programme with the faecal immunochemical test (FIT). Cross-sectional study of 472 participants with a positive FIT who underwent colonoscopy for confirmation of diagnosis between 2013 and 2014. A false-positive result was defined as having a positive FIT (≥20μg haemoglobin per gram of faeces) and follow-up colonoscopy without intermediate/high-risk lesions or cancer. Women showed a two-fold increased likelihood of a false-positive result compared with men (adjusted OR, 2.3; 95%CI, 1.5-3.4), but no female-specific factor was identified. The other variables associated with a false-positive result were successive screening (adjusted OR, 1.5; 95%CI, 1.0-2.2), anal disorders (adjusted OR, 3.1; 95%CI, 2.1-4.5) and the use of proton pump inhibitors (adjusted OR, 1.8; 95%CI, 1.1-2.9). Successive screening and proton pump inhibitor use were associated with FP in men. None of the other drugs were related to a false-positive FIT. Concurrent use of proton pump inhibitors at the time of FIT might increase the likelihood of a false-positive result. Further investigation is needed to determine whether discontinuing them could decrease the false-positive rate. Copyright © 2016 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  9. Estimating False Positive Contamination in Crater Annotations from Citizen Science Data

    NASA Astrophysics Data System (ADS)

    Tar, P. D.; Bugiolacchi, R.; Thacker, N. A.; Gilmour, J. D.

    2017-01-01

    Web-based citizen science often involves the classification of image features by large numbers of minimally trained volunteers, such as the identification of lunar impact craters under the Moon Zoo project. Whilst such approaches facilitate the analysis of large image data sets, the inexperience of users and ambiguity in image content can lead to contamination from false positive identifications. We give an approach, using Linear Poisson Models and image template matching, that can quantify levels of false positive contamination in citizen science Moon Zoo crater annotations. Linear Poisson Models are a form of machine learning which supports predictive error modelling and goodness-of-fits, unlike most alternative machine learning methods. The proposed supervised learning system can reduce the variability in crater counts whilst providing predictive error assessments of estimated quantities of remaining true verses false annotations. In an area of research influenced by human subjectivity, the proposed method provides a level of objectivity through the utilisation of image evidence, guided by candidate crater identifications.

  10. False-negative and false-positive errors in abdominal pain evaluation: failure to diagnose acute appendicitis and unnecessary surgery.

    PubMed

    Graff, L; Russell, J; Seashore, J; Tate, J; Elwell, A; Prete, M; Werdmann, M; Maag, R; Krivenko, C; Radford, M

    2000-11-01

    To test the hypothesis that physician errors (failure to diagnose appendicitis at initial evaluation) correlate with adverse outcome. The authors also postulated that physician errors would correlate with delays in surgery, delays in surgery would correlate with adverse outcomes, and physician errors would occur on patients with atypical presentations. This was a retrospective two-arm observational cohort study at 12 acute care hospitals: 1) consecutive patients who had an appendectomy for appendicitis and 2) consecutive emergency department abdominal pain patients. Outcome measures were adverse events (perforation, abscess) and physician diagnostic performance (false-positive decisions, false-negative decisions). The appendectomy arm of the study included 1, 026 patients with 110 (10.5%) false-positive decisions (range by hospital 4.7% to 19.5%). Of the 916 patients with appendicitis, 170 (18.6%) false-negative decisions were made (range by hospital 10.6% to 27.8%). Patients who had false-negative decisions had increased risks of perforation (r = 0.59, p = 0.058) and of abscess formation (r = 0.81, p = 0.002). For admitted patients, when the inhospital delay before surgery was >20 hours, the risk of perforation was increased [2.9 odds ratio (OR) 95% CI = 1.8 to 4.8]. The amount of delay from initial physician evaluation until surgery varied with physician diagnostic performance: 7.0 hours (95% CI = 6.7 to 7.4) if the initial physician made the diagnosis, 72.4 hours (95% CI = 51.2 to 93.7) if the initial office physician missed the diagnosis, and 63.1 hours (95% CI = 47.9 to 78.4) if the initial emergency physician missed the diagnosis. Patients whose diagnosis was initially missed by the physician had fewer signs and symptoms of appendicitis than patients whose diagnosis was made initially [appendicitis score 2.0 (95% CI = 1.6 to 2.3) vs 6.5 (95% CI = 6.4 to 6.7)]. Older patients (>41 years old) had more false-negative decisions and a higher risk of perforation or

  11. [False positive serum des-gamma-carboxy prothrombin after resection of hepatocellular carcinoma].

    PubMed

    Hiramatsu, Kumiko; Tanaka, Yasuhito; Takagi, Kazumi; Iida, Takayasu; Takasaka, Yoshimitsu; Mizokami, Masashi

    2007-04-01

    Measurements of serum concentrations of des-gamma-carboxy-prothrombin (PIVKA-II) are widely used for diagnosing hepatocellular carcinoma (HCC). Recently, when we evaluated the correlation of PIVKA-II between two commercially available PIVKA-II immunoassay kits (Lumipulse f vs. Picolumi) to introduce it in our hospital, false high values of PIVKA-II were observed in Lumipulse assay. Four(4%) of 100 serum samples showed false high values, and all of them were obtained from patients less than 2 month after curative resection of HCC. Examining additional 7 patients with HCC resection, serum samples from the 5 patients had the same trend. To elucidate the non-specific reaction by Lumipulse assay which utilized alkaline phosphatase (ALP) enzymatic reaction, inhibition assays by various absorbents such as inactive ALP and IgM antibodies were performed. Excess of inactive ALP reduced the high values of PIVKA-II. Note that anti-bleeding sheets (fibrinogen combined drug), which included bovine thrombin, were directly attached on liver of all patients with HCC resection in this study. As the sheets also contaminate ALP and probably produce IgM antibodies to ALP, the IgM may cross-react with anti-PIVKA-II antibodies directly. Taken together, it was suggested that produced antibodies against ALP derived from anti-bleeding sheets led false high values of PIVKA-II in the patients with HCC resection.

  12. False positives complicate ancient pathogen identifications using high-throughput shotgun sequencing

    PubMed Central

    2014-01-01

    Background Identification of historic pathogens is challenging since false positives and negatives are a serious risk. Environmental non-pathogenic contaminants are ubiquitous. Furthermore, public genetic databases contain limited information regarding these species. High-throughput sequencing may help reliably detect and identify historic pathogens. Results We shotgun-sequenced 8 16th-century Mixtec individuals from the site of Teposcolula Yucundaa (Oaxaca, Mexico) who are reported to have died from the huey cocoliztli (‘Great Pestilence’ in Nahautl), an unknown disease that decimated native Mexican populations during the Spanish colonial period, in order to identify the pathogen. Comparison of these sequences with those deriving from the surrounding soil and from 4 precontact individuals from the site found a wide variety of contaminant organisms that confounded analyses. Without the comparative sequence data from the precontact individuals and soil, false positives for Yersinia pestis and rickettsiosis could have been reported. Conclusions False positives and negatives remain problematic in ancient DNA analyses despite the application of high-throughput sequencing. Our results suggest that several studies claiming the discovery of ancient pathogens may need further verification. Additionally, true single molecule sequencing’s short read lengths, inability to sequence through DNA lesions, and limited ancient-DNA-specific technical development hinder its application to palaeopathology. PMID:24568097

  13. False-positive buprenorphine EIA urine toxicology results due to high dose morphine: a case report.

    PubMed

    Tenore, Peter L

    2012-01-01

    In monitoring a patient with chronic pain who was taking high-dose morphine and oxycodone with weekly urine enzymatic immunoassay (EIA) toxicology testing, the authors noted consistent positives for buprenorphine. The patient was not taking buprenorphine, and gas chromatography/mass spectroscopy (GCMS) testing on multiple samples revealed no buprenorphine, indicating a case of false-positive buprenorphine EIAs in a high-dose opiate case. The authors discontinued oxycodone for a period of time and then discontinued morphine. Urine monitoring with EIAs and GCMS revealed false-positive buprenorphine EIAs, which remained only when the patient was taking morphine. When taking only oxycodone and no morphine, urine samples became buprenorphine negative. When morphine was reintroduced, false-positive buprenorphine results resumed. Medical practitioners should be aware that high-dose morphine (with morphine urine levels turning positive within the 15,000 to 28,000 mg/mL range) may produce false-positive buprenorphine EIAs with standard urine EIA toxicology testing.

  14. The OGCleaner: filtering false-positive homology clusters.

    PubMed

    Fujimoto, M Stanley; Suvorov, Anton; Jensen, Nicholas O; Clement, Mark J; Snell, Quinn; Bybee, Seth M

    2017-01-01

    Detecting homologous sequences in organisms is an essential step in protein structure and function prediction, gene annotation and phylogenetic tree construction. Heuristic methods are often employed for quality control of putative homology clusters. These heuristics, however, usually only apply to pairwise sequence comparison and do not examine clusters as a whole. We present the Orthology Group Cleaner (the OGCleaner), a tool designed for filtering putative orthology groups as homology or non-homology clusters by considering all sequences in a cluster. The OGCleaner relies on high-quality orthologous groups identified in OrthoDB to train machine learning algorithms that are able to distinguish between true-positive and false-positive homology groups. This package aims to improve the quality of phylogenetic tree construction especially in instances of lower-quality transcriptome assemblies. https://github.com/byucsl/ogcleaner CONTACT: sfujimoto@gmail.comSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. A Demonstration of Regression False Positive Selection in Data Mining

    ERIC Educational Resources Information Center

    Pinder, Jonathan P.

    2014-01-01

    Business analytics courses, such as marketing research, data mining, forecasting, and advanced financial modeling, have substantial predictive modeling components. The predictive modeling in these courses requires students to estimate and test many linear regressions. As a result, false positive variable selection ("type I errors") is…

  16. View from Spirit's Overwintering Position (False Color)

    NASA Technical Reports Server (NTRS)

    2008-01-01

    NASA's Mars Exploration Rover Spirit has this view northward from the position at the north edge of the 'Home Plate' plateau where the rover will spend its third Martian winter.

    Husband Hill is on the horizon. The dark area in the middle distance is 'El Dorado' sand dune field.

    Spirit used its panoramic camera (Pancam) to capture this image during the rover's 1,448th Martian day, of sol (Jan. 29, 2008).

    This view combines separate images taken through the Pancam filters centered on wavelengths of 753 nanometers, 535 nanometers and 432 nanometers. It is presented in a false-color stretch to bring out subtle color differences in the scene.

  17. Comparison of 4th-Generation HIV Antigen/Antibody Combination Assay With 3rd-Generation HIV Antibody Assays for the Occurrence of False-Positive and False-Negative Results.

    PubMed

    Muthukumar, Alagarraju; Alatoom, Adnan; Burns, Susan; Ashmore, Jerry; Kim, Anne; Emerson, Brian; Bannister, Edward; Ansari, M Qasim

    2015-01-01

    To assess the false-positive and false-negative rates of a 4th-generation human immunodeficiency virus (HIV) assay, the Abbott ARCHITECT, vs 2 HIV 3rd-generation assays, the Siemens Centaur and the Ortho-Clinical Diagnostics Vitros. We examined 123 patient specimens. In the first phase of the study, we compared 99 specimens that had a positive screening result via the 3rd-generation Vitros assay (10 positive, 82 negative, and 7 indeterminate via confirmatory immunofluorescent assay [IFA]/Western blot [WB] testing). In the second phase, we assessed 24 HIV-1 RNA-positive (positive result via the nuclear acid amplification test [NAAT] and negative/indeterminate results via the WB test) specimens harboring acute HIV infection. The 4th-generation ARCHITECT assay yielded fewer false-positive results (n = 2) than the 3rd-generation Centaur (n = 9; P = .02) and Vitros (n = 82; P <.001) assays. One confirmed positive case had a false-negative result via the Centaur assay. When specimens from the 24 patients with acute HIV-1 infection were tested, the ARCHITECT assay yielded fewer false-negative results (n = 5) than the Centaur (n = 10) (P = .13) and the other 3rd-generation tests (n = 16) (P = .002). This study indicates that the 4th-generation ARCHITECT HIV assay yields fewer false-positive and false-negative results than the 3rd-generation HIV assays we tested. Copyright© by the American Society for Clinical Pathology (ASCP).

  18. Variation in false-positive rates of mammography reading among 1067 radiologists: a population-based assessment.

    PubMed

    Tan, Alai; Freeman, Daniel H; Goodwin, James S; Freeman, Jean L

    2006-12-01

    The accuracy of mammography reading varies among radiologists. We conducted a population-based assessment on radiologist variation in false- positive rates of screening mammography and its associated radiologist characteristics. About 27,394 screening mammograms interpreted by 1067 radiologists were identified from a 5% non-cancer sample of Medicare claims during 1998-1999. The data were linked to the American Medical Association Masterfile to obtain radiologist characteristics. Multilevel logistic regression models were used to examine the radiologist variation in false-positive rates of screening mammography and the associated radiologist characteristics. Radiologists varied substantially in the false-positive rates of screening mammography (ranging from 1.5 to 24.1%, adjusting for patient characteristics). A longer time period since graduation is associated with lower false-positive rates (odds ratio [OR] for every 10 years increase: 0.87, 95% Confidence Interval [CI], 0.81-0.94) and female radiologists had higher false-positive rates than male radiologists (OR = 1.25, 95% CI, 1.05-1.49), adjusting for patient and other radiologist characteristics. The unmeasured factors contributed to about 90% of the between-radiologist variance. Radiologists varied greatly in accuracy of mammography reading. Female and more recently trained radiologists had higher false-positive rates. The variation among radiologists was largely due to unmeasured factors, especially unmeasured radiologist factors. If our results are confirmed in further studies, they suggest that system-level interventions would be required to reduce variation in mammography interpretation.

  19. Assessment of potential false positives via orbitrap-based untargeted lipidomics from rat tissues.

    PubMed

    Xu, Lina; Wang, Xueying; Jiao, Yupei; Liu, Xiaohui

    2018-02-01

    Untargeted lipidomics is increasingly popular due to the broad coverage of lipid species. Data dependent MS/MS acquisition is commonly used in order to acquire sufficient information for confident lipid assignment. However, although lipids are identified based on MS/MS confirmation, a number of false positives are still observed. Here, we discuss several causes of introducing lipid false identifications in untargeted analysis. Phosphotidylcholines and cholesteryl esters generate in-source fragmentation to produce dimethylated phosphotidylethanolamine and free cholesterol. Dimerization of fatty acid results in false identification of fatty acid ester of hydroxyl fatty acid. Realizing these false positives is able to improve confidence of results acquired from untargeted analysis. Besides, thresholds are established for lipids identified using LipidSearch v4.1.16 software to reduce unreliable results. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Shear wave elastography in the diagnosis of breast non-mass lesions: factors associated with false negative and false positive results.

    PubMed

    Park, So Yoon; Choi, Ji Soo; Han, Boo-Kyung; Ko, Eun Young; Ko, Eun Sook

    2017-09-01

    To investigate factors related to false shear wave elastography (SWE) results for breast non-mass lesions (NMLs) detected by B-mode US. This retrospective study enrolled 152 NMLs detected by B-mode US and later pathologically confirmed (79 malignant, 73 benign). All lesions underwent B-mode US and SWE. Quantitative (mean elasticity [E mean ]) and qualitative (maximum stiffness colour) SWE parameters were assessed, and 'E mean  > 85.1 kPa' or 'stiff colour (green to red)' determined malignancy. Final SWE results were matched to pathology results. Multivariate logistic regression analysis identified factors associated with false SWE results for diagnosis of breast NMLs. Associated calcifications (E mean : odds ratio [OR] = 7.60, P < 0.01; maximum stiffness colour: OR = 6.30, P = 0.02), in situ cancer compared to invasive cancer (maximum stiffness colour: OR = 5.29, P = 0.02), and lesion size (E mean : OR = 0.90, P < 0.01; maximum stiffness colour: OR = 0.91, P = 0.01) were significantly associated with false negative SWE results for malignant NMLs. Distance from the nipple (E mean : OR = 0.84, P = 0.03; maximum stiffness colour: OR = 0.93, P = 0.04) was significantly associated with false positive SWE results for benign NMLs. Presence of associated calcifications, absence of the invasive component, and smaller lesion size for malignant NMLs and shorter distance from the nipple for benign NMLs are factors significantly associated with false SWE results. • Calcification and size are associated with false negative SWE in malignant NMLs. • In situ cancer is associated with false negative SWE in malignant NMLs. • Distance from the nipple is associated with false positive SWE in benign NMLs. • These factors need consideration when performing SWE on breast NMLs.

  1. New Constraints on the False Positive Rate for Short-Period Kepler Planet Candidates

    NASA Astrophysics Data System (ADS)

    Colón, Knicole D.; Morehead, Robert C.; Ford, Eric B.

    2015-01-01

    The Kepler space mission has discovered thousands of potential planets orbiting other stars, thereby setting the stage for in-depth studies of different populations of planets. We present new multi-wavelength transit photometry of small (Rp < 6 Earth radii), short-period (P < 6 days) Kepler planet candidates acquired with the Gran Telescopio Canarias. Multi-wavelength transit photometry allows us to search for wavelength-dependent transit depths and subsequently identify eclipsing binary false positives (which are especially prevalent at the shortest orbital periods). We combine these new observations of three candidates with previous results for five other candidates (Colón & Ford 2011 and Colón, Ford, & Morehead 2012) to provide new constraints on the false positive rate for small, close-in candidates. In our full sample, we identify four candidates as viable planets and four as eclipsing binary false positives. We therefore find a higher false positive rate for small, close-in candidates compared to the lower false positive rate of ~10% determined by other studies for the full sample of Kepler planet candidates (e.g. Fressin et al. 2013). We also discuss the dearth of known planets with periods less than ~2.5 days and radii between ~3 and 11 Earth radii (the so-called 'sub-Jovian desert'), since the majority of the candidates in our study are located in or around this 'desert.' The lack of planets with these orbital and physical properties is not expected to be due to observational bias, as short-period planets are generally easier to detect (especially if they are larger or more massive than Earth). We consider the implications of our results for the other ~20 Kepler planet candidates located in this desert. Characterizing these candidates will allow us to better understand the formation processes of this apparently rare class of planets.

  2. Are false-positive rates leading to an overestimation of noise-induced hearing loss?

    PubMed

    Schlauch, Robert S; Carney, Edward

    2011-04-01

    To estimate false-positive rates for rules proposed to identify early noise-induced hearing loss (NIHL) using the presence of notches in audiograms. Audiograms collected from school-age children in a national survey of health and nutrition (the Third National Health and Nutrition Examination Survey [NHANES III]; National Center for Health Statistics, 1994) were examined using published rules for identifying noise notches at various pass-fail criteria. These results were compared with computer-simulated "flat" audiograms. The proportion of these identified as having a noise notch is an estimate of the false-positive rate for a particular rule. Audiograms from the NHANES III for children 6-11 years of age yielded notched audiograms at rates consistent with simulations, suggesting that this group does not have significant NIHL. Further, pass-fail criteria for rules suggested by expert clinicians, applied to NHANES III audiometric data, yielded unacceptably high false-positive rates. Computer simulations provide an effective method for estimating false-positive rates for protocols used to identify notched audiograms. Audiometric precision could possibly be improved by (a) eliminating systematic calibration errors, including a possible problem with reference levels for TDH-style earphones; (b) repeating and averaging threshold measurements; and (c) using earphones that yield lower variability for 6.0 and 8.0 kHz--2 frequencies critical for identifying noise notches.

  3. Consensus-based identification of factors related to false-positives in ultrasound scanning of synovitis and tenosynovitis.

    PubMed

    Ikeda, Kei; Narita, Akihiro; Ogasawara, Michihiro; Ohno, Shigeru; Kawahito, Yutaka; Kawakami, Atsushi; Ito, Hiromu; Matsushita, Isao; Suzuki, Takeshi; Misaki, Kenta; Ogura, Takehisa; Kamishima, Tamotsu; Seto, Yohei; Nakahara, Ryuichi; Kaneko, Atsushi; Nakamura, Takayuki; Henmi, Mihoko; Fukae, Jun; Nishida, Keiichiro; Sumida, Takayuki; Koike, Takao

    2016-01-01

    We aimed to identify causes of false-positives in ultrasound scanning of synovial/tenosynovial/bursal inflammation and provide corresponding imaging examples. We first performed systematic literature review to identify previously reported causes of false-positives. We next determined causes of false-positives and corresponding example images for educational material through Delphi exercises and discussion by 15 experts who were an instructor and/or a lecturer in the 2013 advanced course for musculoskeletal ultrasound organized by Japan College of Rheumatology Committee for the Standardization of Musculoskeletal Ultrasonography. Systematic literature review identified 11 articles relevant to sonographic false-positives of synovial/tenosynovial inflammation. Based on these studies, 21 candidate causes of false-positives were identified in the consensus meeting. Of these items, 11 achieved a predefined consensus (≥ 80%) in Delphi exercise and were classified as follows: (I) Gray-scale assessment [(A) non-specific synovial findings and (B) normal anatomical structures which can mimic synovial lesions due to either their low echogenicity or anisotropy]; (II) Doppler assessment [(A) Intra-articular normal vessels and (B) reverberation)]. Twenty-four corresponding examples with 49 still and 23 video images also achieved consensus. Our study provides a set of representative images that can help sonographers to understand false-positives in ultrasound scanning of synovitis and tenosynovitis.

  4. [Interpretation of false positive results of biochemical prenatal tests].

    PubMed

    Sieroszewski, Piotr; Słowakiewicz, Katarzyna; Perenc, Małgorzata

    2010-03-01

    Modern, non-invasive prenatal diagnostics based on biochemical and ultrasonographic markers of fetal defects allows us to calculate the risk of fetal chromosomal aneuploidies with high sensitivity and specificity An introduction of biochemical, non-invasive prenatal tests turned out to result in frequent false positive results of these tests in cases when invasive diagnostics does not confirm fetal defects. However prospective analysis of these cases showed numerous complications in the third trimester of the pregnancies.

  5. Evaluation of MTANNs for eliminating false-positive with different computer aided pulmonary nodules detection software.

    PubMed

    Shi, Zhenghao; Ma, Jiejue; Feng, Yaning; He, Lifeng; Suzuki, Kenji

    2015-11-01

    MTANN (Massive Training Artificial Neural Network) is a promising tool, which applied to eliminate false-positive for thoracic CT in recent years. In order to evaluate whether this method is feasible to eliminate false-positive of different CAD schemes, especially, when it is applied to commercial CAD software, this paper evaluate the performance of the method for eliminating false-positives produced by three different versions of commercial CAD software for lung nodules detection in chest radiographs. Experimental results demonstrate that the approach is useful in reducing FPs for different computer aided lung nodules detection software in chest radiographs.

  6. VarBin, a novel method for classifying true and false positive variants in NGS data

    PubMed Central

    2013-01-01

    Background Variant discovery for rare genetic diseases using Illumina genome or exome sequencing involves screening of up to millions of variants to find only the one or few causative variant(s). Sequencing or alignment errors create "false positive" variants, which are often retained in the variant screening process. Methods to remove false positive variants often retain many false positive variants. This report presents VarBin, a method to prioritize variants based on a false positive variant likelihood prediction. Methods VarBin uses the Genome Analysis Toolkit variant calling software to calculate the variant-to-wild type genotype likelihood ratio at each variant change and position divided by read depth. The resulting Phred-scaled, likelihood-ratio by depth (PLRD) was used to segregate variants into 4 Bins with Bin 1 variants most likely true and Bin 4 most likely false positive. PLRD values were calculated for a proband of interest and 41 additional Illumina HiSeq, exome and whole genome samples (proband's family or unrelated samples). At variant sites without apparent sequencing or alignment error, wild type/non-variant calls cluster near -3 PLRD and variant calls typically cluster above 10 PLRD. Sites with systematic variant calling problems (evident by variant quality scores and biases as well as displayed on the iGV viewer) tend to have higher and more variable wild type/non-variant PLRD values. Depending on the separation of a proband's variant PLRD value from the cluster of wild type/non-variant PLRD values for background samples at the same variant change and position, the VarBin method's classification is assigned to each proband variant (Bin 1 to Bin 4). Results To assess VarBin performance, Sanger sequencing was performed on 98 variants in the proband and background samples. True variants were confirmed in 97% of Bin 1 variants, 30% of Bin 2, and 0% of Bin 3/Bin 4. Conclusions These data indicate that VarBin correctly classifies the majority of true

  7. US women's attitudes to false positive mammography results and detection of ductal carcinoma in situ: cross sectional survey

    PubMed Central

    Schwartz, Lisa M; Woloshin, Steven; Sox, Harold C; Fischhoff, Baruch; Welch, H Gilbert

    2000-01-01

    Objective To determine women's attitudes to and knowledge of both false positive mammography results and the detection of ductal carcinoma in situ after screening mammography. Design Cross sectional survey. Setting United States. Participants 479 women aged 18-97 years who did not report a history of breast cancer. Main outcome measures Attitudes to and knowledge of false positive results and the detection of ductal carcinoma in situ after screening mammography. Results Women were aware that false positive results do occur. Their median estimate of the false positive rate for 10 years of annual screening was 20% (25th percentile estimate, 10%; 75th percentile estimate, 45%). The women were highly tolerant of false positives: 63% thought that 500 or more false positives per life saved was reasonable and 37% would tolerate 10 000 or more. Women who had had a false positive result (n=76) expressed the same high tolerance: 39% would tolerate 10 000 or more false positives. 62% of women did not want to take false positive results into account when deciding about screening. Only 8% of women thought that mammography could harm a woman without breast cancer, and 94% doubted the possibility of non-progressive breast cancers. Few had heard about ductal carcinoma in situ, a cancer that may not progress, but when informed, 60% of women wanted to take into account the possibility of it being detected when deciding about screening. Conclusions Women are aware of false positives and seem to view them as an acceptable consequence of screening mammography. In contrast, most women are unaware that screening can detect cancers that may never progress but feel that such information would be relevant. Education should perhaps focus less on false positives and more on the less familiar outcome of detection of ductal carcinoma in situ. PMID:10856064

  8. Risk of Breast Cancer in Women with False-Positive Results according to Mammographic Features.

    PubMed

    Castells, Xavier; Torá-Rocamora, Isabel; Posso, Margarita; Román, Marta; Vernet-Tomas, Maria; Rodríguez-Arana, Ana; Domingo, Laia; Vidal, Carmen; Baré, Marisa; Ferrer, Joana; Quintana, María Jesús; Sánchez, Mar; Natal, Carmen; Espinàs, Josep A; Saladié, Francina; Sala, María

    2016-08-01

    Purpose To assess the risk of breast cancer in women with false-positive screening results according to radiologic classification of mammographic features. Materials and Methods Review board approval was obtained, with waiver of informed consent. This retrospective cohort study included 521 200 women aged 50-69 years who underwent screening as part of the Spanish Breast Cancer Screening Program between 1994 and 2010 and who were observed until December 2012. Cox proportional hazards regression analysis was used to estimate the age-adjusted hazard ratio (HR) of breast cancer and the 95% confidence interval (CI) in women with false-positive mammograms as compared with women with negative mammograms. Separate models were adjusted for screen-detected and interval cancers and for screen-film and digital mammography. Time without a breast cancer diagnosis was plotted by using Kaplan-Meier curves. Results When compared with women with negative mammograms, the age-adjusted HR of cancer in women with false-positive results was 1.84 (95% CI: 1.73, 1.95; P < .001). The risk was higher in women who had calcifications, whether they were (HR, 2.73; 95% CI: 2.28, 3.28; P < .001) or were not (HR, 2.24; 95% CI: 2.02, 2.48; P < .001) associated with masses. Women in whom mammographic features showed changes in subsequent false-positive results were those who had the highest risk (HR, 9.13; 95% CI: 8.28, 10.07; P < .001). Conclusion Women with false-positive results had an increased risk of breast cancer, particularly women who had calcifications at mammography. Women who had more than one examination with false-positive findings and in whom the mammographic features changed over time had a highly increased risk of breast cancer. Previous mammographic features might yield useful information for further risk-prediction models and personalized follow-up screening protocols. (©) RSNA, 2016 Online supplemental material is available for this article.

  9. Detecting False Positives in Multielement Designs: Implications for Brief Assessments

    ERIC Educational Resources Information Center

    Bartlett, Sara M.; Rapp, John T.; Henrickson, Marissa L.

    2011-01-01

    The authors assessed the extent to which multielement designs produced false positives using continuous duration recording (CDR) and interval recording with 10-s and 1-min interval sizes. Specifically, they created 6,000 graphs with multielement designs that varied in the number of data paths, and the number of data points per data path, using a…

  10. When good news is bad news: psychological impact of false positive diagnosis of HIV.

    PubMed

    Bhattacharya, Rahul; Barton, Simon; Catalan, Jose

    2008-05-01

    HIV testing is known to be stressful, however the impact of false positive HIV results on individuals is not well documented. This is a series of four case who developed psychological difficulties and psychiatric morbidities after being informed they had been misdiagnosed with HIV-positive status. We look into documented cases of misdiagnosis and potential risks of misdiagnosis. The case series highlights the implications a false diagnosis HIV-positive status can have, even when the diagnosis is rectified. Impact of misdiagnosis of HIV can lead to psychosocial difficulties and psychiatric morbidity, have public health and epidemiological implications and can lead to medico-legal conflict. This further reiterates the importance of HIV testing carried out ethically and sensitively, and in line with guidelines, respecting confidentiality and consent, and offering counselling pre-test and post-test, being mindful of the reality of erroneous and false positive HIV test results. The implications of misdiagnosis are for the individual, their partners and social contacts, as well as for the community.

  11. Evaluation of fecal elastase and serum cholecystokinin in dogs with a false positive fecal elastase test.

    PubMed

    Steiner, J M; Rehfeld, J F; Pantchev, N

    2010-01-01

    An assay for the measurement of pancreatic elastase in dog feces has been introduced. The goal of this study was to evaluate the rate of false-positive fecal-elastase test results in dogs with suspected exocrine pancreatic insufficiency (EPI) and to assess serum cholecystokinin (CCK) concentrations in dogs with a false positive fecal elastase test result. Twenty-six fecal and serum samples from dogs suspected of EPI, for which samples had been submitted to a commercial laboratory (Vet Med Labor) for analysis. Prospective study. Serum trypsin-like immunoreactivity (TLI) was measured in 26 dogs with a decreased fecal elastase concentration of <10 microg/g feces. Serum CCK concentrations were measured in 21 of these dogs. Of 26 dogs with a decreased fecal elastase concentration, 6 (23%) had serum TLI concentrations within or above the reference range. Serum CCK concentrations were significantly higher in dogs with a true positive fecal elastase test result (median: 1.1 pmol/L; range: 0.1-3.3 pmol/L) than in those with a false positive fecal elastase test result (median: 0.1 pmol/L; range: 0.1-0.9 pmol/L; P value = .0163). The rate of false positive fecal elastase test results was high in this group of dogs, suggesting that diagnosis of EPI must be confirmed by other means. The decreased CCK concentration in dogs with a false positive fecal elastase test result could suggest that false positive results are because of decreased stimulation of exocrine pancreatic function caused by other conditions.

  12. Finkelstein's test: a descriptive error that can produce a false positive.

    PubMed

    Elliott, B G

    1992-08-01

    Over the last three decades an error in performing Finkelstein's test has crept into the English literature in both text books and journals. This error can produce a false-positive, and if relied upon, a wrong diagnosis can be made, leading to inappropriate surgery.

  13. Computerized mass detection in whole breast ultrasound images: reduction of false positives using bilateral subtraction technique

    NASA Astrophysics Data System (ADS)

    Ikedo, Yuji; Fukuoka, Daisuke; Hara, Takeshi; Fujita, Hiroshi; Takada, Etsuo; Endo, Tokiko; Morita, Takako

    2007-03-01

    The comparison of left and right mammograms is a common technique used by radiologists for the detection and diagnosis of masses. In mammography, computer-aided detection (CAD) schemes using bilateral subtraction technique have been reported. However, in breast ultrasonography, there are no reports on CAD schemes using comparison of left and right breasts. In this study, we propose a scheme of false positive reduction based on bilateral subtraction technique in whole breast ultrasound images. Mass candidate regions are detected by using the information of edge directions. Bilateral breast images are registered with reference to the nipple positions and skin lines. A false positive region is detected based on a comparison of the average gray values of a mass candidate region and a region with the same position and same size as the candidate region in the contralateral breast. In evaluating the effectiveness of the false positive reduction method, three normal and three abnormal bilateral pairs of whole breast images were employed. These abnormal breasts included six masses larger than 5 mm in diameter. The sensitivity was 83% (5/6) with 13.8 (165/12) false positives per breast before applying the proposed reduction method. By applying the method, false positives were reduced to 4.5 (54/12) per breast without removing a true positive region. This preliminary study indicates that the bilateral subtraction technique is effective for improving the performance of a CAD scheme in whole breast ultrasound images.

  14. [False positive of DUPAN-2 caused by IgM-human anti mouse antibody].

    PubMed

    Abe, Masaki; Hyoki, Miyuki; Abe, Ikurou; Kaito, Ken; Takagi, Ichirou

    2012-11-01

    We investigated a case in our experience presenting false-positive for DUPAN-2 by IgM-human anti mouse antibody (HAMA). A female aged 40s has been treated in our hospital from 2003. Her serum level of DUPAN-2 in 2005 and 2006 were 110 U/mL and 140 U/mL respectively. While this level was increased to 770 U/ml in 2007, and kept in the higher level so far. Around years of 2007, no meaning changes was detected by radiological and laboratory tests, and there was no significant change in her clinical signs and symptoms and medications. The elevation of DUPAN-2 was thought as a false-positive phenomenon and the mechanism was investigated. As results, no dilution lineality was found, and absorption test showed a 95% reduction of DUPAN-2 levels not by IgG and IgA, but IgM-specific antiserum. Dithiothreitoldeacylation test with neuraminidase, and absorption test with HBR-1, IIR, and mouse IgM serum, it was suggested that the IgM with HAMA activity of the patient reacted with mouse monoclonal antibodies in reagents. Moreover, the HPLC-eluted fraction of DUPAN-2 of this patients was detected in the fraction of IgM, which as different from that of a control pancreatic cancer patient. Above these data, elevation of DUPAN-2 in this patient was a false positive phenomenon by IgM-HAMA reacting with mouse monoclonal antibodies in reagents. Although there are few reported cases of false positive phenomenon in DUPAN-2 measurement, we have to pay attention to such phenomenon when detecting an unlikely higher levels that could not be explained by clinical information.

  15. False-positive tangible outcomes of functional analyses.

    PubMed

    Rooker, Griffin W; Iwata, Brian A; Harper, Jill M; Fahmie, Tara A; Camp, Erin M

    2011-01-01

    Functional analysis (FA) methodology is the most precise method for identifying variables that maintain problem behavior. Occasionally, however, results of an FA may be influenced by idiosyncratic sensitivity to aspects of the assessment conditions. For example, data from several studies suggest that inclusion of a tangible condition during an FA may be prone to a false-positive outcome, although the extent to which tangible reinforcement routinely produces such outcomes is unknown. We examined susceptibility to tangible reinforcement by determining whether a new response was acquired more readily when exposed to a tangible contingency relative to others commonly used in an FA (Study 1), and whether problem behavior known not to have a social function nevertheless emerged when exposed to tangible reinforcement (Study 2). Results indicated that inclusion of items in the tangible condition should be done with care and that selection should be based on those items typically found in the individual's environment.

  16. Generating false negatives and false positives for As and Mo concentrations in groundwater due to well installation.

    PubMed

    Wallis, Ilka; Pichler, Thomas

    2018-08-01

    Groundwater monitoring relies on the acquisition of 'representative' groundwater samples, which should reflect the ambient water quality at a given location. However, drilling of a monitoring well for sample acquisition has the potential to perturb groundwater conditions to a point that may prove to be detrimental to the monitoring objective. Following installation of 20 monitoring wells in close geographic proximity in central Florida, opposing concentration trends for As and Mo were observed. In the first year after well installation As and Mo concentrations increased in some wells by a factor of 2, while in others As and Mo concentrations decreased by a factor of up to 100. Given this relatively short period of time, a natural change in groundwater composition of such magnitude is not expected, leaving well installation itself as the likely cause for the observed concentration changes. Hence, initial concentrations were identified as 'false negatives' if concentrations increased with time or as 'false positives' if concentrations decreased. False negatives were observed if concentrations were already high, i.e., the As or Mo were present at the time of drilling. False positives were observed if concentrations were relatively lower, i.e., As or Mo were present at low concentrations of approximately 1 to 2μg/L before drilling, but then released from the aquifer matrix as a result of drilling. Generally, As and Mo were present in the aquifer matrix in either pyrite or organic matter, both of which are susceptible to dissolution if redox conditions change due to the addition of oxygen. Thus, introduction of an oxidant into an anoxic aquifer through use of an oxygen saturated drilling fluid served as the conceptual model for the trends where concentrations decreased with time. Mixing between drilling fluid and groundwater (i.e., dilution) was used as the conceptual model for scenarios where increasing trends were observed. Conceptual models were successfully tested

  17. Verification of false-positive blood culture results generated by the BACTEC 9000 series by eubacterial 16S rDNA and panfungal 18S rDNA directed polymerase chain reaction (PCR).

    PubMed

    Daxboeck, Florian; Dornbusch, Hans Jürgen; Krause, Robert; Assadian, Ojan; Wenisch, Christoph

    2004-01-01

    A small but significant proportion of blood cultures processed by the BACTEC 9000 series systems is signaled positive, while subsequent Gram's stain and culture on solid media yield no pathogens. In this study, 15 "false-positive" vials (7 aerobes, 8 anaerobes) from 15 patients were investigated for the presence of bacteria and fungi by eubacterial 16S rDNA and panfungal 18S rDNA amplification, respectively. All samples turned out negative by both methods. Most patients (7) had neutropenia, which does not support the theory that high leukocyte counts enhance the generation of false-positive results. In conclusion, the results of this study indicate that false-negative results generated by the BACTEC 9000 series are inherent to the automated detection and not due to the growth of fastidious organisms.

  18. Cumulative risk of false positive test in relation to breast symptoms in mammography screening: a historical prospective cohort study.

    PubMed

    Singh, Deependra; Pitkäniemi, Janne; Malila, Nea; Anttila, Ahti

    2016-09-01

    Mammography has been found effective as the primary screening test for breast cancer. We estimated the cumulative probability of false positive screening test results with respect to symptom history reported at screen. A historical prospective cohort study was done using individual screening data from 413,611 women aged 50-69 years with 2,627,256 invitations for mammography screening between 1992 and 2012 in Finland. Symptoms (lump, retraction, and secretion) were reported at 56,805 visits, and 48,873 visits resulted in a false positive mammography result. Generalized linear models were used to estimate the probability of at least one false positive test and true positive at screening visits. The estimates were compared among women with and without symptoms history. The estimated cumulative probabilities were 18 and 6 % for false positive and true positive results, respectively. In women with a history of a lump, the cumulative probabilities of false positive test and true positive were 45 and 16 %, respectively, compared to 17 and 5 % with no reported lump. In women with a history of any given symptom, the cumulative probabilities of false positive test and true positive were 38 and 13 %, respectively. Likewise, women with a history of a 'lump and retraction' had the cumulative false positive probability of 56 %. The study showed higher cumulative risk of false positive tests and more cancers detected in women who reported symptoms compared to women who did not report symptoms at screen. The risk varies substantially, depending on symptom types and characteristics. Information on breast symptoms influences the balance of absolute benefits and harms of screening.

  19. The psychological impact of a false-positive screening mammogram in Barcelona.

    PubMed

    Espasa, Rebecca; Murta-Nascimento, Cristiane; Bayés, Ramón; Sala, Maria; Casamitjana, Montserrat; Macià, Francesc; Castells, Xavier

    2012-12-01

    The purpose of this study was to ascertain the psychological impact of mammographic screening for women who receive negative results and for those who need additional non-invasive and invasive complementary investigations to exclude breast cancer (false positives). One hundred fifty women who attended a breast cancer screening programme in Barcelona, aged 50-69 years, were included in this study: 50 with negative results and 100 with false positive mammograms (50 underwent non-invasive and 50 underwent invasive complementary investigations). Participants worried little until they underwent mammography, but worries increased when a telephone call notified the women of the need for further testing. A substantial proportion of women requiring further assessment reported that they were at least somewhat worried about having breast cancer throughout the screening process (P < 0.0001). Nevertheless, levels of anxiety and depression, measured by the Hospital Anxiety and Depression Scale, showed no statistically significant differences among the three groups. In conclusion, although the women showed no psychological morbidity, there is a substantial psychological response in those with an abnormal screening mammogram.

  20. False-positive psychology: undisclosed flexibility in data collection and analysis allows presenting anything as significant.

    PubMed

    Simmons, Joseph P; Nelson, Leif D; Simonsohn, Uri

    2011-11-01

    In this article, we accomplish two things. First, we show that despite empirical psychologists' nominal endorsement of a low rate of false-positive findings (≤ .05), flexibility in data collection, analysis, and reporting dramatically increases actual false-positive rates. In many cases, a researcher is more likely to falsely find evidence that an effect exists than to correctly find evidence that it does not. We present computer simulations and a pair of actual experiments that demonstrate how unacceptably easy it is to accumulate (and report) statistically significant evidence for a false hypothesis. Second, we suggest a simple, low-cost, and straightforwardly effective disclosure-based solution to this problem. The solution involves six concrete requirements for authors and four guidelines for reviewers, all of which impose a minimal burden on the publication process.

  1. Proteins interacting with cloning scars: a source of false positive protein-protein interactions.

    PubMed

    Banks, Charles A S; Boanca, Gina; Lee, Zachary T; Florens, Laurence; Washburn, Michael P

    2015-02-23

    A common approach for exploring the interactome, the network of protein-protein interactions in cells, uses a commercially available ORF library to express affinity tagged bait proteins; these can be expressed in cells and endogenous cellular proteins that copurify with the bait can be identified as putative interacting proteins using mass spectrometry. Control experiments can be used to limit false-positive results, but in many cases, there are still a surprising number of prey proteins that appear to copurify specifically with the bait. Here, we have identified one source of false-positive interactions in such studies. We have found that a combination of: 1) the variable sequence of the C-terminus of the bait with 2) a C-terminal valine "cloning scar" present in a commercially available ORF library, can in some cases create a peptide motif that results in the aberrant co-purification of endogenous cellular proteins. Control experiments may not identify false positives resulting from such artificial motifs, as aberrant binding depends on sequences that vary from one bait to another. It is possible that such cryptic protein binding might occur in other systems using affinity tagged proteins; this study highlights the importance of conducting careful follow-up studies where novel protein-protein interactions are suspected.

  2. Proteins interacting with cloning scars: a source of false positive protein-protein interactions

    PubMed Central

    Banks, Charles A. S.; Boanca, Gina; Lee, Zachary T.; Florens, Laurence; Washburn, Michael P.

    2015-01-01

    A common approach for exploring the interactome, the network of protein-protein interactions in cells, uses a commercially available ORF library to express affinity tagged bait proteins; these can be expressed in cells and endogenous cellular proteins that copurify with the bait can be identified as putative interacting proteins using mass spectrometry. Control experiments can be used to limit false-positive results, but in many cases, there are still a surprising number of prey proteins that appear to copurify specifically with the bait. Here, we have identified one source of false-positive interactions in such studies. We have found that a combination of: 1) the variable sequence of the C-terminus of the bait with 2) a C-terminal valine “cloning scar” present in a commercially available ORF library, can in some cases create a peptide motif that results in the aberrant co-purification of endogenous cellular proteins. Control experiments may not identify false positives resulting from such artificial motifs, as aberrant binding depends on sequences that vary from one bait to another. It is possible that such cryptic protein binding might occur in other systems using affinity tagged proteins; this study highlights the importance of conducting careful follow-up studies where novel protein-protein interactions are suspected. PMID:25704442

  3. Is it time to sound an alarm about false-positive cell-free DNA testing for fetal aneuploidy?

    PubMed

    Mennuti, Michael T; Cherry, Athena M; Morrissette, Jennifer J D; Dugoff, Lorraine

    2013-11-01

    Testing cell-free DNA (cfDNA) in maternal blood samples has been shown to have very high sensitivity for the detection of fetal aneuploidy with very low false-positive results in high-risk patients who undergo invasive prenatal diagnosis. Recent observation in clinical practice of several cases of positive cfDNA tests for trisomy 18 and trisomy 13, which were not confirmed by cytogenetic testing of the pregnancy, may reflect a limitation of the positive predictive value of this quantitative testing, particularly when it is used to detect rare aneuploidies. Analysis of a larger number of false-positive cases is needed to evaluate whether these observations reflect the positive predictive value that should be expected. Infrequently, mechanisms (such as low percentage mosaicism or confined placental mosaicism) might also lead to positive cfDNA testing that is not concordant with standard prenatal cytogenetic diagnosis. The need to explore these and other possible causes of false-positive cfDNA testing is exemplified by 2 of these cases. Additional evaluation of cfDNA testing in clinical practice and a mechanism for the systematic reporting of false-positive and false-negative cases will be important before this test is offered widely to the general population of low-risk obstetric patients. In the meantime, incorporating information about the positive predictive value in pretest counseling and in clinical laboratory reports is recommended. These experiences reinforce the importance of offering invasive testing to confirm cfDNA results before parental decision-making. Copyright © 2013 Mosby, Inc. All rights reserved.

  4. Easy fix for clinical laboratories for the false-positive defect with the Abbott AxSym total beta-hCG test.

    PubMed

    Cole, Laurence A; Khanlian, Sarah A

    2004-05-01

    False-positive hCG results can lead to erroneous diagnoses and needless chemotherapy and surgery. In the last 2 years, eight publications described cases involving false-positive hCG tests; all eight involved the AxSym test. We investigated the source of this abundance of cases and a simple fix that may be used by clinical laboratories. False-positive hCG was primarily identified by absence of hCG in urine and varying or negative hCG results in alternative tests. Seventeen false-positive serum samples in the AxSym test were evaluated undiluted and at twofold dilution with diluent containing excess goat serum or immunoglobulin. We identified 58 patients with false-positive hCG, 47 of 58 due to the Abbott AxSym total hCGbeta test (81%). Sixteen of 17 of these "false-positive" results (mean 100 mIU/ml) became undetectable when tested again after twofold dilution. A simple twofold dilution with this diluent containing excess goat serum or immunoglobulin completely protected 16 of 17 samples from patients having false-positive results. It is recommended that laboratories using this test use twofold dilution as a minimum to prevent false-positive results.

  5. Potential for false positive HIV test results with the serial rapid HIV testing algorithm.

    PubMed

    Baveewo, Steven; Kamya, Moses R; Mayanja-Kizza, Harriet; Fatch, Robin; Bangsberg, David R; Coates, Thomas; Hahn, Judith A; Wanyenze, Rhoda K

    2012-03-19

    Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation. Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold). However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2%) were HIV negative. Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals.

  6. The Illusion of the Positive: The impact of natural and induced mood on older adults’ false recall

    PubMed Central

    Emery, Lisa; Hess, Thomas M.; Elliot, Tonya

    2012-01-01

    Recent research suggests that affective and motivational processes can influence age differences in memory. In the current study, we examine the impact of both natural and induced mood state on age differences in false recall. Older and younger adults performed a version of the Deese-Roediger-McDermott (DRM; Roediger & McDermott, 1995) false memory paradigm in either their natural mood state or after a positive or negative mood induction. Results indicated that, after accounting for age differences in basic cognitive function, age-related differences in positive mood during the testing session were related to increased false recall in older adults. Inducing older adults into a positive mood also exacerbated age differences in false memory. In contrast, veridical recall did not appear to be systematically influenced by mood. Together, these results suggest that positive mood states can impact older adults’ information processing and potentially increase underlying cognitive age differences. PMID:22292431

  7. Analyzing False Positives of Four Questions in the Force Concept Inventory

    ERIC Educational Resources Information Center

    Yasuda, Jun-ichro; Mae, Naohiro; Hull, Michael M.; Taniguchi, Masa-aki

    2018-01-01

    In this study, we analyze the systematic error from false positives of the Force Concept Inventory (FCI). We compare the systematic errors of question 6 (Q.6), Q.7, and Q.16, for which clearly erroneous reasoning has been found, with Q.5, for which clearly erroneous reasoning has not been found. We determine whether or not a correct response to a…

  8. Limited Agreement of Independent RNAi Screens for Virus-Required Host Genes Owes More to False-Negative than False-Positive Factors

    PubMed Central

    Wang, Zhishi; Craven, Mark; Newton, Michael A.; Ahlquist, Paul

    2013-01-01

    Systematic, genome-wide RNA interference (RNAi) analysis is a powerful approach to identify gene functions that support or modulate selected biological processes. An emerging challenge shared with some other genome-wide approaches is that independent RNAi studies often show limited agreement in their lists of implicated genes. To better understand this, we analyzed four genome-wide RNAi studies that identified host genes involved in influenza virus replication. These studies collectively identified and validated the roles of 614 cell genes, but pair-wise overlap among the four gene lists was only 3% to 15% (average 6.7%). However, a number of functional categories were overrepresented in multiple studies. The pair-wise overlap of these enriched-category lists was high, ∼19%, implying more agreement among studies than apparent at the gene level. Probing this further, we found that the gene lists implicated by independent studies were highly connected in interacting networks by independent functional measures such as protein-protein interactions, at rates significantly higher than predicted by chance. We also developed a general, model-based approach to gauge the effects of false-positive and false-negative factors and to estimate, from a limited number of studies, the total number of genes involved in a process. For influenza virus replication, this novel statistical approach estimates the total number of cell genes involved to be ∼2,800. This and multiple other aspects of our experimental and computational results imply that, when following good quality control practices, the low overlap between studies is primarily due to false negatives rather than false-positive gene identifications. These results and methods have implications for and applications to multiple forms of genome-wide analysis. PMID:24068911

  9. [Evaluation of performance and false positivity of Mediace RPR test that uses a chemistry autoanalyzer].

    PubMed

    Noh, Jaekwang; Ko, Hak Hyun; Yun, Yeomin; Choi, Young Sook; Lee, Sang Gon; Shin, Sue; Han, Kyou Sup; Song, Eun Young

    2008-08-01

    We evaluated the performance and false positive rate of Mediace RPR test (Sekisui, Japan), a newly introduced nontreponemal test using a chemistry autoanalyzer. The sensitivity of Mediace RPR test was analyzed using sera from 50 patients with syphilis in different stages (8 primary, 7 secondary, and 35 latent), 14 sera positive with fluorescent treponemal antibody absorption (FTA-ABS) IgM, and 74 sera positive with conventional rapid plasma regain (RPR) card test (Asan, Korea) and also positive with Treponema pallidum hemagglutination (TPHA) test or FTA-ABS IgG test. The specificity was analyzed on 108 healthy blood donors. We also performed RPR card test on 302 sera that had been tested positive with Mediace RPR test and also performed TPHA or FTA-ABS IgG test to analyze the false positive rate of Mediace RPR test. A cutoff value of 0.5 R.U. (RPR unit) was used for Mediace RPR test. Mediace RPR test on syphilitic sera of different stages (primary, secondary, and latent stages) and FTA-ABS IgM positive sera showed a sensitivity of 100%, 100%, 82.9% and 100%, respectively. Among the 74 sera positive with conventional RPR card test and TPHA or FTA-ABS IgG test, 55 were positive with Mediace test. The specificity of Mediace RPR test on blood donors was 97.2%. Among the 302 sera positive with Mediace RPR test, 137 sera (45.4%) were negative by RPR card and TPHA/FTA-ABS IgG tests. Although the sensitivities of Mediace RPR were good for primary and secondary syphilis, due to its high negative rate of Mediace RPR over the conventional RPR positive samples, further studies are necessary whether it can replace conventional nontreponemal test for screening purpose. Moreover, in view of the high false positive rate, positive results by Mediace RPR test should be confirmed with treponemal tests.

  10. Modeling false positive detections in species occurrence data under different study designs.

    PubMed

    Chambert, Thierry; Miller, David A W; Nichols, James D

    2015-02-01

    The occurrence of false positive detections in presence-absence data, even when they occur infrequently, can lead to severe bias when estimating species occupancy patterns. Building upon previous efforts to account for this source of observational error, we established a general framework to model false positives in occupancy studies and extend existing modeling approaches to encompass a broader range of sampling designs. Specifically, we identified three common sampling designs that are likely to cover most scenarios encountered by researchers. The different designs all included ambiguous detections, as well as some known-truth data, but their modeling differed in the level of the model hierarchy at which the known-truth information was incorporated (site level or observation level). For each model, we provide the likelihood, as well as R and BUGS code needed for implementation. We also establish a clear terminology and provide guidance to help choosing the most appropriate design and modeling approach.

  11. The illusion of the positive: the impact of natural and induced mood on older adults' false recall.

    PubMed

    Emery, Lisa; Hess, Thomas M; Elliot, Tonya

    2012-11-01

    Recent research suggests that affective and motivational processes can influence age differences in memory. In the current study, we examine the impact of both natural and induced mood state on age differences in false recall. Older and younger adults performed a version of the Deese-Roediger-McDermott (DRM; Roediger & McDermott, 1995 , Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 803) false memory paradigm in either their natural mood state or after a positive or negative mood induction. Results indicated that, after accounting for age differences in basic cognitive function, age-related differences in positive mood during the testing session were related to increased false recall in older adults. Inducing older adults into a positive mood also exacerbated age differences in false memory. In contrast, veridical recall did not appear to be systematically influenced by mood. Together, these results suggest that positive mood states can impact older adults' information processing and potentially increase underlying cognitive age differences.

  12. False positive fecal coliform in biosolid samples assayed using A-1 medium.

    PubMed

    Baker, Katherine H; Redmond, Brady; Herson, Diane S

    2005-01-01

    Two most probable number (MPN) methods-lauryl tryptose broth with Escherichia coli broth confirmation and direct A-1 broth incubation (A-1)--were compared for the enumeration of fecal coliform in lime-treated biosolid. Fecal coliform numbers were significantly higher using the A-1 method. Analysis of positive A-1 tubes, however, indicated that a high percentage of these were false positives. Therefore, the use of A-1 broth for 40 CFR Part 503 Pathogen Reduction (CFR, 1993) compliance testing is not recommended.

  13. Potential for false positive HIV test results with the serial rapid HIV testing algorithm

    PubMed Central

    2012-01-01

    Background Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation. Results Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold). However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2%) were HIV negative. Conclusion Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals. PMID:22429706

  14. Buffer substitution in malaria rapid diagnostic tests causes false-positive results

    PubMed Central

    2010-01-01

    Background Malaria rapid diagnostic tests (RDTs) are kits that generally include 20 to 25 test strips or cassettes, but only a single buffer vial. In field settings, laboratory staff occasionally uses saline, distilled water (liquids for parenteral drugs dilution) or tap water as substitutes for the RDT kit's buffer to compensate for the loss of a diluent bottle. The present study assessed the effect of buffer substitution on the RDT results. Methods Twenty-seven RDT brands were run with EDTA-blood samples of five malaria-free subjects, who were negative for rheumatoid factor and antinuclear antibodies. Saline, distilled water and tap water were used as substitute liquids. RDTs were also run with distilled water, without adding blood. Results were compared to those obtained with the RDT kit's buffer and Plasmodium positive samples. Results Only eight cassettes (in four RDT brands) showed no control line and were considered invalid. Visible test lines occurred for at least one malaria-free sample and one of the substitutes in 20/27 (74%) RDT brands (saline: n = 16; distilled water: n = 17; and tap water: n = 20), and in 15 RDTs which were run with distilled water only. They occurred for all Plasmodium antigens and RDT formats (two-, three- and four-band RDTs). Clearance of the background of the strip was excellent except for saline. The aspects (colour, intensity and crispness) of the control and the false-positive test lines were similar to those obtained with the RDT kits' buffer and Plasmodium positive samples. Conclusion Replacement of the RDT kit's dedicated buffer by saline, distilled water and tap water can cause false-positive test results. PMID:20650003

  15. Detection of Yersinia enterocolitica serotype O:9 in the faeces of cattle with false positive reactions in serological tests for brucellosis in Ireland.

    PubMed

    O'Grady, Don; Kenny, Kevin; Power, Seamus; Egan, John; Ryan, Fergus

    2016-10-01

    Intestinal infection by Yersinia enterocolitica serotype O:9 (YeO9) in cattle has been linked to false positive serological reactivity (FPSR) in diagnostic tests for brucellosis. Although eradicated in Ireland, brucellosis monitoring still identifies seropositive animals, usually one or two (termed singletons) per herd, which are classed as FPSR. To investigate a link between FPSR and YeO9, faeces and blood were collected from singleton FPSR cattle, and from companion animals, in eight selected herds with more than one FPSR animal, for YeO9 culture and Brucella serology. YeO9 was isolated from 76/474 (16%) FPSR singletons in 309 herds, but not from any of 621 animals in 122 control non-FPSR herds. In the FPSR herds 52/187 (27.8%) animals were culture positive, and 17% of the isolates were from seronegative animals. Seropositive animals were more likely to have a rising antibody titre when culture positive. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. The Direct Imaging Search for Earth 2.0: Quantifying Biases and Planetary False Positives

    NASA Astrophysics Data System (ADS)

    Guimond, Claire Marie; Cowan, Nicolas B.

    2018-06-01

    Direct imaging is likely the best way to characterize the atmospheres of Earth-sized exoplanets in the habitable zone of Sun-like stars. Previously, Stark et al. estimated the Earth twin yield of future direct imaging missions, such as LUVOIR and HabEx. We extend this analysis to other types of planets, which will act as false positives for Earth twins. We define an Earth twin as any exoplanet within half an e-folding of 1 au in semimajor axis and 1 {R}\\oplus in planetary radius, orbiting a G-dwarf. Using Monte Carlo analyses, we quantify the biases and planetary false-positive rates of Earth searches. That is, given a pale dot at the correct projected separation and brightness to be a candidate Earth, what are the odds that it is, in fact, an Earth twin? Our notional telescope has a diameter of 10 m, an inner working angle of 3λ/D, and an outer working angle of 10λ/D (62 mas and 206 mas at 1.0 μm). With no precursor knowledge and one visit per star, 77% of detected candidate Earths are actually un-Earths; their mean radius is 2.3 {R}\\oplus , a sub-Neptune. The odds improve if we image every planet at its optimal orbital phase, either by relying on precursor knowledge, or by performing multi-epoch direct imaging. In such a targeted search, 47% of detected Earth twin candidates are false positives, and they have a mean radius of 1.7 {R}\\oplus . The false-positive rate is insensitive to stellar spectral type and the assumption of circular orbits.

  17. False-positive findings in Cochrane meta-analyses with and without application of trial sequential analysis: an empirical review.

    PubMed

    Imberger, Georgina; Thorlund, Kristian; Gluud, Christian; Wetterslev, Jørn

    2016-08-12

    Many published meta-analyses are underpowered. We explored the role of trial sequential analysis (TSA) in assessing the reliability of conclusions in underpowered meta-analyses. We screened The Cochrane Database of Systematic Reviews and selected 100 meta-analyses with a binary outcome, a negative result and sufficient power. We defined a negative result as one where the 95% CI for the effect included 1.00, a positive result as one where the 95% CI did not include 1.00, and sufficient power as the required information size for 80% power, 5% type 1 error, relative risk reduction of 10% or number needed to treat of 100, and control event proportion and heterogeneity taken from the included studies. We re-conducted the meta-analyses, using conventional cumulative techniques, to measure how many false positives would have occurred if these meta-analyses had been updated after each new trial. For each false positive, we performed TSA, using three different approaches. We screened 4736 systematic reviews to find 100 meta-analyses that fulfilled our inclusion criteria. Using conventional cumulative meta-analysis, false positives were present in seven of the meta-analyses (7%, 95% CI 3% to 14%), occurring more than once in three. The total number of false positives was 14 and TSA prevented 13 of these (93%, 95% CI 68% to 98%). In a post hoc analysis, we found that Cochrane meta-analyses that are negative are 1.67 times more likely to be updated (95% CI 0.92 to 2.68) than those that are positive. We found false positives in 7% (95% CI 3% to 14%) of the included meta-analyses. Owing to limitations of external validity and to the decreased likelihood of updating positive meta-analyses, the true proportion of false positives in meta-analysis is probably higher. TSA prevented 93% of the false positives (95% CI 68% to 98%). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  18. Commercial radioimmunoassay for beta subunit of human chorionic gonadotropin: falsely positive determinations due to elevated serum luteinizing hormone

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fowler, J.E. Jr.; Platoff, G.E.; Kubrock, C.A.

    1982-01-01

    Among 17 men who had received seemingly curative treatment for unilateral non-seminomatous germ cell tumors for the testis and who had consistently normal serum human chorionic gonadotropin (HCG) levels at a reference laboratory, 7 (41%) had at least one falsely positive commercial serum HCG determination. To investigate the cause of these falsely positive determinations the authors measured the cross reactivity of luteinizing hormone (LH) and follicle stimulating hormone (FSH) standards in the commercial HCG assay, and studied the relationships between commercial HCG levels and serum LH levels, serum FSH levels and gonadal status in men with and without normal gonadalmore » function. The falsely positive HCG determinations appeared to be due to elevated serum LH levels and cross reactivity of LH in the commercial HCG assay because: 1) there was substantial cross reactivity of the LH standards in the commercial assay, 2) the serum LH was elevated in four of six men with solitary testes, 3) there was a striking correlation between elevated serum LH levels and falsely elevated commercial HCG levels in ten men with solitary or absent testes, and 4) there were no falsely positive HCG determinations in 13 normal men but there were falsely positive HCG determinations in seven of ten anorchid men.« less

  19. Abort Trigger False Positive and False Negative Analysis Methodology for Threshold-Based Abort Detection

    NASA Technical Reports Server (NTRS)

    Melcher, Kevin J.; Cruz, Jose A.; Johnson Stephen B.; Lo, Yunnhon

    2015-01-01

    This paper describes a quantitative methodology for bounding the false positive (FP) and false negative (FN) probabilities associated with a human-rated launch vehicle abort trigger (AT) that includes sensor data qualification (SDQ). In this context, an AT is a hardware and software mechanism designed to detect the existence of a specific abort condition. Also, SDQ is an algorithmic approach used to identify sensor data suspected of being corrupt so that suspect data does not adversely affect an AT's detection capability. The FP and FN methodologies presented here were developed to support estimation of the probabilities of loss of crew and loss of mission for the Space Launch System (SLS) which is being developed by the National Aeronautics and Space Administration (NASA). The paper provides a brief overview of system health management as being an extension of control theory; and describes how ATs and the calculation of FP and FN probabilities relate to this theory. The discussion leads to a detailed presentation of the FP and FN methodology and an example showing how the FP and FN calculations are performed. This detailed presentation includes a methodology for calculating the change in FP and FN probabilities that result from including SDQ in the AT architecture. To avoid proprietary and sensitive data issues, the example incorporates a mixture of open literature and fictitious reliability data. Results presented in the paper demonstrate the effectiveness of the approach in providing quantitative estimates that bound the probability of a FP or FN abort determination.

  20. Hemorrhoids detected at colonoscopy: an infrequent cause of false-positive fecal immunochemical test results.

    PubMed

    van Turenhout, Sietze T; Oort, Frank A; Terhaar sive Droste, Jochim S; Coupé, Veerle M H; van der Hulst, Rene W; Loffeld, Ruud J; Scholten, Pieter; Depla, Annekatrien C T M; Bouman, Anneke A; Meijer, Gerrit A; Mulder, Chris J J; van Rossum, Leo G M

    2012-07-01

    Colorectal cancer screening by fecal immunochemical tests (FITs) is hampered by frequent false-positive (FP) results and thereby the risk of complications and strain on colonoscopy capacity. Hemorrhoids might be a plausible cause of FP results. To determine the contribution of hemorrhoids to the frequency of FP FIT results. Retrospective analysis from prospective cohort study. Five large teaching hospitals, including 1 academic hospital. All subjects scheduled for elective colonoscopy. FIT before bowel preparation. Frequency of FP FIT results in subjects with hemorrhoids as the only relevant abnormality compared with FP FIT results in subjects with no relevant abnormalities. Logistic regression analysis to determine colonic abnormalities influencing FP results. In 2855 patients, 434 had positive FIT results: 213 had advanced neoplasia and 221 had FP results. In 9 individuals (4.1%; 95% CI, 1.4-6.8) with an FP FIT result, hemorrhoids were the only abnormality. In univariate unadjusted analysis, subjects with hemorrhoids as the only abnormality did not have more positive results (9/134; 6.7%) compared with subjects without any abnormalities (43/886; 4.9%; P = .396). Logistic regression identified hemorrhoids, nonadvanced polyps, and a group of miscellaneous abnormalities, all significantly influencing false positivity. Of 1000 subjects with hemorrhoids, 67 would have FP results, of whom 18 would have FP results because of hemorrhoids only. Potential underreporting of hemorrhoids; high-risk individuals. Hemorrhoids in individuals participating in colorectal cancer screening will probably not lead to a substantial number of false-positive test results. Copyright © 2012 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

  1. Retrospective imaging study on the diagnosis of pathological false positive iodine-131 scans in patients with thyroid cancer.

    PubMed

    Jia, Qiang; Meng, Zhaowei; Tan, Jian; Zhang, Guizhi; He, Yajing; Sun, Haoran; Yu, Chunshui; Li, Dong; Zheng, Wei; Wang, Renfei; Wang, Shen; Li, Xue; Zhang, Jianping; Hu, Tianpeng; Liu, N A; Upadhyaya, Arun

    2015-11-01

    Iodine-131 (I-131) therapy and post-therapy I-131 scanning are essential in the management of differentiated thyroid cancer (DTC). However, pathological false positive I-131 scans can lead to misdiagnosis and inappropriate I-131 treatment. This retrospective study aimed to investigate the best imaging modality for the diagnosis of pathological false positive I-131 scans in a DTC patient cohort, and to determine its incidence. DTC patient data archived from January 2008 to January 2010 was retrieved. Post-therapeutic I-131 scans were conducted and interpreted. The imaging modalities of magnetic resonance imaging (MRI), computed tomography and ultrasonography were applied and compared to check all suspected lesions. Biopsy or needle aspiration was conducted for patients who consented to the acquisition of histopathological confirmation. Data for 156 DTC patients were retrieved. Only 6 cases of pathological false-positives were found among these (incidence, 3.85%), which included 3 cases of thymic hyperplasia in the mediastinum, 1 case of pleomorphic adenoma in the parapharyngeal space and 1 case of thyroglossal duct cyst in the neck. MRI was demonstrated as the best imaging modality for diagnosis due to its superior soft tissue resolution. However, no imaging modality was able to identify the abdominal false positive-lesions observed in 2 cases, one of whom also had thymic hyperplasia. In conclusion, pathological false positive I-131 scans occurred with an incidence of 3.85%. MRI was the best imaging modality for diagnosing these pathological false-positives.

  2. The probability of false positives in zero-dimensional analyses of one-dimensional kinematic, force and EMG trajectories.

    PubMed

    Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

    2016-06-14

    A false positive is the mistake of inferring an effect when none exists, and although α controls the false positive (Type I error) rate in classical hypothesis testing, a given α value is accurate only if the underlying model of randomness appropriately reflects experimentally observed variance. Hypotheses pertaining to one-dimensional (1D) (e.g. time-varying) biomechanical trajectories are most often tested using a traditional zero-dimensional (0D) Gaussian model of randomness, but variance in these datasets is clearly 1D. The purpose of this study was to determine the likelihood that analyzing smooth 1D data with a 0D model of variance will produce false positives. We first used random field theory (RFT) to predict the probability of false positives in 0D analyses. We then validated RFT predictions via numerical simulations of smooth Gaussian 1D trajectories. Results showed that, across a range of public kinematic, force/moment and EMG datasets, the median false positive rate was 0.382 and not the assumed α=0.05, even for a simple two-sample t test involving N=10 trajectories per group. The median false positive rate for experiments involving three-component vector trajectories was p=0.764. This rate increased to p=0.945 for two three-component vector trajectories, and to p=0.999 for six three-component vectors. This implies that experiments involving vector trajectories have a high probability of yielding 0D statistical significance when there is, in fact, no 1D effect. Either (a) explicit a priori identification of 0D variables or (b) adoption of 1D methods can more tightly control α. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. False-positive result when a diphenylcarbazide spot test is used on trivalent chromium-passivated zinc surfaces.

    PubMed

    Reveko, Valeriia; Lampert, Felix; Din, Rameez U; Thyssen, Jacob P; Møller, Per

    2018-05-01

    A colorimetric 1,5-diphenylcarbazide (DPC)-based spot test can be used to identify hexavalent chromium on various metallic and leather surfaces. DPC testing on trivalent chromium-passivated zinc surfaces has unexpectedly given positive results in some cases, apparently indicating the presence of hexavalent chromium; however, the presence of hexavalent chromium has never been confirmed with more sensitive and accurate test methods. To examine the presence of hexavalent chromium on trivalent chromium-passivated zinc surfaces with a DPC-based spot test. A colorimetric DPC spot test was used for the initial detection of hexavalent chromium on new and 1-year-aged trivalent chromium-passivated zinc surfaces. Then, X-ray photoelectron spectroscopy (XPS) was performed for all samples. The DPC spot test indicated the presence of hexavalent chromium in aged, but not new, trivalent chromium passivation on zinc; however, subsequent analysis by XPS could not confirm the presence of chromium in a hexavalent state. Unintended oxidation of DPC induced by atmospheric corrosion is suggested as a possible reason for the false-positive reaction of the DPC test on a trivalent chromium-passivated zinc surface. Further validation of the use of the DPC test for chromium-containing metallic surfaces is required. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Reducing false-positive detections by combining two stage-1 computer-aided mass detection algorithms

    NASA Astrophysics Data System (ADS)

    Bedard, Noah D.; Sampat, Mehul P.; Stokes, Patrick A.; Markey, Mia K.

    2006-03-01

    In this paper we present a strategy for reducing the number of false-positives in computer-aided mass detection. Our approach is to only mark "consensus" detections from among the suspicious sites identified by different "stage-1" detection algorithms. By "stage-1" we mean that each of the Computer-aided Detection (CADe) algorithms is designed to operate with high sensitivity, allowing for a large number of false positives. In this study, two mass detection methods were used: (1) Heath and Bowyer's algorithm based on the average fraction under the minimum filter (AFUM) and (2) a low-threshold bi-lateral subtraction algorithm. The two methods were applied separately to a set of images from the Digital Database for Screening Mammography (DDSM) to obtain paired sets of mass candidates. The consensus mass candidates for each image were identified by a logical "and" operation of the two CADe algorithms so as to eliminate regions of suspicion that were not independently identified by both techniques. It was shown that by combining the evidence from the AFUM filter method with that obtained from bi-lateral subtraction, the same sensitivity could be reached with fewer false-positives per image relative to using the AFUM filter alone.

  5. A deep 3D residual CNN for false-positive reduction in pulmonary nodule detection.

    PubMed

    Jin, Hongsheng; Li, Zongyao; Tong, Ruofeng; Lin, Lanfen

    2018-05-01

    The automatic detection of pulmonary nodules using CT scans improves the efficiency of lung cancer diagnosis, and false-positive reduction plays a significant role in the detection. In this paper, we focus on the false-positive reduction task and propose an effective method for this task. We construct a deep 3D residual CNN (convolution neural network) to reduce false-positive nodules from candidate nodules. The proposed network is much deeper than the traditional 3D CNNs used in medical image processing. Specifically, in the network, we design a spatial pooling and cropping (SPC) layer to extract multilevel contextual information of CT data. Moreover, we employ an online hard sample selection strategy in the training process to make the network better fit hard samples (e.g., nodules with irregular shapes). Our method is evaluated on 888 CT scans from the dataset of the LUNA16 Challenge. The free-response receiver operating characteristic (FROC) curve shows that the proposed method achieves a high detection performance. Our experiments confirm that our method is robust and that the SPC layer helps increase the prediction accuracy. Additionally, the proposed method can easily be extended to other 3D object detection tasks in medical image processing. © 2018 American Association of Physicists in Medicine.

  6. False-Positive Xpert MTB/RIF Results in Retested Patients with Previous Tuberculosis: Frequency, Profile, and Prospective Clinical Outcomes.

    PubMed

    Theron, Grant; Venter, Rouxjeane; Smith, Liezel; Esmail, Aliasgar; Randall, Philippa; Sood, Vishesh; Oelfese, Suzette; Calligaro, Greg; Warren, Robin; Dheda, Keertan

    2018-03-01

    Globally, Xpert MTB/RIF (Xpert) is the most widely used PCR test for the diagnosis of tuberculosis (TB). Positive results in previously treated patients, which are due to old DNA or active disease, are a diagnostic dilemma. We prospectively retested sputum from 238 patients, irrespective of current symptoms, who were previously diagnosed to be Xpert positive and treated successfully. Patients who retested as Xpert positive and culture negative were exhaustively investigated (repeat culture, chest radiography, bronchoscopy with bronchoalveolar lavage, long-term clinical follow-up). We evaluated whether the duration since previous treatment completion, mycobacterial burden (the Xpert cycle threshold [ C T ] value), and reclassification of Xpert-positive results with a very low semiquantitation level to Xpert-negative results reduced the rate of false positivity. A total of 229/238 (96%) of patients were culture negative. Sixteen of 229 (7%) were Xpert positive a median of 11 months (interquartile range, 5 to 19 months) after treatment completion. The specificity was 93% (95% confidence interval [CI], 89 to 96%). Nine of 15 (40%) Xpert-positive, culture-negative patients reverted to Xpert negative after 2 to 3 months (1 patient declined further participation). Patients with false-positive Xpert results had a lower mycobacterial burden than patients with true-positive Xpert results ( C T , 28.7 [95% CI, 27.2 to 30.4] versus 17.6 [95% CI, 16.9 to 18.2]; P < 0.001), an increased likelihood of a chest radiograph not compatible with active TB (5/15 patients versus 0/5 patients; P = 0.026), and less-viscous sputum (15/16 patients versus 2/5 patients whose sputum was graded as mucoid or less; P = 0.038). All patients who initially retested as Xpert positive and culture negative ("Xpert false positive") were clinically well without treatment after follow-up. The duration since the previous treatment poorly predicted false-positive results (a duration of ≤2 years identified

  7. Reduction of false-positive recalls using a computerized mammographic image feature analysis scheme

    NASA Astrophysics Data System (ADS)

    Tan, Maxine; Pu, Jiantao; Zheng, Bin

    2014-08-01

    The high false-positive recall rate is one of the major dilemmas that significantly reduce the efficacy of screening mammography, which harms a large fraction of women and increases healthcare cost. This study aims to investigate the feasibility of helping reduce false-positive recalls by developing a new computer-aided diagnosis (CAD) scheme based on the analysis of global mammographic texture and density features computed from four-view images. Our database includes full-field digital mammography (FFDM) images acquired from 1052 recalled women (669 positive for cancer and 383 benign). Each case has four images: two craniocaudal (CC) and two mediolateral oblique (MLO) views. Our CAD scheme first computed global texture features related to the mammographic density distribution on the segmented breast regions of four images. Second, the computed features were given to two artificial neural network (ANN) classifiers that were separately trained and tested in a ten-fold cross-validation scheme on CC and MLO view images, respectively. Finally, two ANN classification scores were combined using a new adaptive scoring fusion method that automatically determined the optimal weights to assign to both views. CAD performance was tested using the area under a receiver operating characteristic curve (AUC). The AUC = 0.793  ±  0.026 was obtained for this four-view CAD scheme, which was significantly higher at the 5% significance level than the AUCs achieved when using only CC (p = 0.025) or MLO (p = 0.0004) view images, respectively. This study demonstrates that a quantitative assessment of global mammographic image texture and density features could provide useful and/or supplementary information to classify between malignant and benign cases among the recalled cases, which may eventually help reduce the false-positive recall rate in screening mammography.

  8. Thyroid Fine-Needle Aspiration Cytology:Causes of false-positive results.

    PubMed

    Malheiros, Daniela C; Canberk, Sule; Poller, David N; Schmitt, Fernando

    2018-05-16

    In this paper, we aim to focus on false positive results in the evaluation of thyroid aspirations, covering cystic, inflammatory, follicular and oncocytic lesions, papillary carcinoma, and medullary carcinoma of thyroid. The recently described entity, "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP), is also discussed detailing the impact of its introduction on the sensitivity and specificity of thyroid FNA, as well as the use of molecular tests for diagnostics. Medicolegal issues in relation to current practice in English law are also described. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  9. Multilevel Contextual 3-D CNNs for False Positive Reduction in Pulmonary Nodule Detection.

    PubMed

    Dou, Qi; Chen, Hao; Yu, Lequan; Qin, Jing; Heng, Pheng-Ann

    2017-07-01

    False positive reduction is one of the most crucial components in an automated pulmonary nodule detection system, which plays an important role in lung cancer diagnosis and early treatment. The objective of this paper is to effectively address the challenges in this task and therefore to accurately discriminate the true nodules from a large number of candidates. We propose a novel method employing three-dimensional (3-D) convolutional neural networks (CNNs) for false positive reduction in automated pulmonary nodule detection from volumetric computed tomography (CT) scans. Compared with its 2-D counterparts, the 3-D CNNs can encode richer spatial information and extract more representative features via their hierarchical architecture trained with 3-D samples. More importantly, we further propose a simple yet effective strategy to encode multilevel contextual information to meet the challenges coming with the large variations and hard mimics of pulmonary nodules. The proposed framework has been extensively validated in the LUNA16 challenge held in conjunction with ISBI 2016, where we achieved the highest competition performance metric (CPM) score in the false positive reduction track. Experimental results demonstrated the importance and effectiveness of integrating multilevel contextual information into 3-D CNN framework for automated pulmonary nodule detection in volumetric CT data. While our method is tailored for pulmonary nodule detection, the proposed framework is general and can be easily extended to many other 3-D object detection tasks from volumetric medical images, where the targeting objects have large variations and are accompanied by a number of hard mimics.

  10. Effect of protocol-related variables and women's characteristics on the cumulative false-positive risk in breast cancer screening

    PubMed Central

    Román, R.; Sala, M.; Salas, D.; Ascunce, N.; Zubizarreta, R.; Castells, X.

    2012-01-01

    Background: Reducing the false-positive risk in breast cancer screening is important. We examined how the screening-protocol and women's characteristics affect the cumulative false-positive risk. Methods: This is a retrospective cohort study of 1 565 364 women aged 45–69 years who underwent 4 739 498 screening mammograms from 1990 to 2006. Multilevel discrete hazard models were used to estimate the cumulative false-positive risk over 10 sequential mammograms under different risk scenarios. Results: The factors affecting the false-positive risk for any procedure and for invasive procedures were double mammogram reading [odds ratio (OR) = 2.06 and 4.44, respectively], two mammographic views (OR = 0.77 and 1.56, respectively), digital mammography (OR = 0.83 for invasive procedures), premenopausal status (OR = 1.31 and 1.22, respectively), use of hormone replacement therapy (OR = 1.03 and 0.84, respectively), previous invasive procedures (OR = 1.52 and 2.00, respectively), and a familial history of breast cancer (OR = 1.18 and 1.21, respectively). The cumulative false-positive risk for women who started screening at age 50–51 was 20.39% [95% confidence interval (CI) 20.02–20.76], ranging from 51.43% to 7.47% in the highest and lowest risk profiles, respectively. The cumulative risk for invasive procedures was 1.76% (95% CI 1.66–1.87), ranging from 12.02% to 1.58%. Conclusions: The cumulative false-positive risk varied widely depending on the factors studied. These findings are relevant to provide women with accurate information and to improve the effectiveness of screening programs. PMID:21430183

  11. CHROMOSPHERIC EMISSION OF PLANET CANDIDATE HOST STARS: A WAY TO IDENTIFY FALSE POSITIVES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Karoff, Christoffer; Knudsen, Mads Faurschou; Albrecht, Simon

    2016-10-10

    It has been hypothesized that the presence of closely orbiting giant planets is associated with enhanced chromospheric emission of their host stars. The main cause for such a relation would likely be enhanced dynamo action induced by the planet. We present measurements of chromospheric emission in 234 planet candidate systems from the Kepler mission. This ensemble includes 37 systems with giant-planet candidates, which show a clear emission enhancement. The enhancement, however, disappears when systems that are also identified as eclipsing binary candidates are removed from the ensemble. This suggests that a large fraction of the giant-planet candidate systems with chromosphericmore » emission stronger than the Sun are not giant-planet systems, but false positives. Such false-positive systems could be tidally interacting binaries with strong chromospheric emission. This hypothesis is supported by an analysis of 188 eclipsing binary candidates that show increasing chromospheric emission as function of decreasing orbital period.« less

  12. Whole-body scintigraphy with radioiodine-131. A comprehensive list of false-positives with some examples.

    PubMed

    McDougall, I R

    1995-10-01

    Whole-body scintigraphy with radioiodine-131 is an important diagnostic test in the management of patients with differentiated thyroid cancer who have undergone surgical treatment. The scan can demonstrate the presence of residual thyroid or functioning metastases in lymph nodes or distant sites. However, there are a number of potential pitfalls in the interpretation of this scan that could lead to a false-positive diagnosis of cancer. The scintiscans are presented for five patients in whom uptake outside of the thyroid was not due to functioning metastases. Some of these abnormalities are physiologic, such as uptake of iodine in the gastrointestinal tract. A comprehensive list of false-positive results are tabulated.

  13. Cumulative False-Positive QuantiFERON-TB Interferon-γ Release Assay Results.

    PubMed

    Gamsky, Thomas E; Lum, Thomas; Hung-Fan, Melody; Green, Jon A

    2016-05-01

    Despite reports of unreliability, the QuantiFERON-TB interferon-γ release assay is increasingly used for the annual screening of individuals at risk for latent tuberculosis. Continued use of the QuantiFERON-TB assay suggests the need for more definitive evidence of its reproducibility and accuracy. To examine reproducibility and the accumulation of false-positive test results when the QuantiFERON-TB is repeated annually and to examine the validity of confirming positive test results with the performance of a second QuantiFERON-TB. We performed a retrospective, longitudinal evaluation of results from serial screening of a cohort of emergency responders from 2001 to 2013. Results of tuberculin tests and QuantiFERON-TB tests performed annually as part of a mandated first responder examination were retroactively reviewed. In this population, positive results occurred in new individuals each year. QuantiFERON-TB results were positive in 80 of 557 tuberculin test-negative individuals examined annually for a maximum of 7 years. Only 10 individuals with initially positive results remained positive when the test was repeated the next year, and 9 of these 10 were QuantiFERON-TB-negative within 3 years. The number of individuals with a positive result increased annually, and, after 7 years, 32 (27.4%) of 117 people had a positive result. When viewed in the context of the extensive literature documenting unreliable QuantiFERON-TB test performance, our findings of frequent, cumulative, sporadic, and irreproducible positive results support discontinuing the use of the QuantiFERON-TB assay for the diagnosis of latent tuberculosis in low-risk populations.

  14. Reduction of false-positives in a CAD scheme for automated detection of architectural distortion in digital mammography

    NASA Astrophysics Data System (ADS)

    de Oliveira, Helder C. R.; Mencattini, Arianna; Casti, Paola; Martinelli, Eugenio; di Natale, Corrado; Catani, Juliana H.; de Barros, Nestor; Melo, Carlos F. E.; Gonzaga, Adilson; Vieira, Marcelo A. C.

    2018-02-01

    This paper proposes a method to reduce the number of false-positives (FP) in a computer-aided detection (CAD) scheme for automated detection of architectural distortion (AD) in digital mammography. AD is a subtle contraction of breast parenchyma that may represent an early sign of breast cancer. Due to its subtlety and variability, AD is more difficult to detect compared to microcalcifications and masses, and is commonly found in retrospective evaluations of false-negative mammograms. Several computer-based systems have been proposed for automated detection of AD in breast images. The usual approach is automatically detect possible sites of AD in a mammographic image (segmentation step) and then use a classifier to eliminate the false-positives and identify the suspicious regions (classification step). This paper focus on the optimization of the segmentation step to reduce the number of FPs that is used as input to the classifier. The proposal is to use statistical measurements to score the segmented regions and then apply a threshold to select a small quantity of regions that should be submitted to the classification step, improving the detection performance of a CAD scheme. We evaluated 12 image features to score and select suspicious regions of 74 clinical Full-Field Digital Mammography (FFDM). All images in this dataset contained at least one region with AD previously marked by an expert radiologist. The results showed that the proposed method can reduce the false positives of the segmentation step of the CAD scheme from 43.4 false positives (FP) per image to 34.5 FP per image, without increasing the number of false negatives.

  15. Center not liable for defamation from false-positive hepatitis test.

    PubMed

    1997-04-18

    The Nebraska Court of Appeals ruled that [name removed] does not have a cause of action against the Lincoln Plasma Center in Lincoln, NE. The center blacklisted him as a carrier of hepatitis B virus; subsequent tests proved [name removed] was uninfected. [Name removed], a paid plasma donator, was placed on an ineligible list after he tested positive for the hepatitis B surface antigen. [Name removed] sued, alleging that Lincoln defamed him by publishing false information to blood banks about his eligibility to donate. The Court of Appeals upheld a trial court's directed verdict because there was no evidence that the plasma center acted in malice.

  16. Are False-Positive Rates Leading to an Overestimation of Noise-Induced Hearing Loss?

    ERIC Educational Resources Information Center

    Schlauch, Robert S.; Carney, Edward

    2011-01-01

    Purpose: To estimate false-positive rates for rules proposed to identify early noise-induced hearing loss (NIHL) using the presence of notches in audiograms. Method: Audiograms collected from school-age children in a national survey of health and nutrition (the Third National Health and Nutrition Examination Survey [NHANES III]; National Center…

  17. Diagnostic classification of macular ganglion cell and retinal nerve fiber layer analysis: differentiation of false-positives from glaucoma.

    PubMed

    Kim, Ko Eun; Jeoung, Jin Wook; Park, Ki Ho; Kim, Dong Myung; Kim, Seok Hwan

    2015-03-01

    To investigate the rate and associated factors of false-positive diagnostic classification of ganglion cell analysis (GCA) and retinal nerve fiber layer (RNFL) maps, and characteristic false-positive patterns on optical coherence tomography (OCT) deviation maps. Prospective, cross-sectional study. A total of 104 healthy eyes of 104 normal participants. All participants underwent peripapillary and macular spectral-domain (Cirrus-HD, Carl Zeiss Meditec Inc, Dublin, CA) OCT scans. False-positive diagnostic classification was defined as yellow or red color-coded areas for GCA and RNFL maps. Univariate and multivariate logistic regression analyses were used to determine associated factors. Eyes with abnormal OCT deviation maps were categorized on the basis of the shape and location of abnormal color-coded area. Differences in clinical characteristics among the subgroups were compared. (1) The rate and associated factors of false-positive OCT maps; (2) patterns of false-positive, color-coded areas on the GCA deviation map and associated clinical characteristics. Of the 104 healthy eyes, 42 (40.4%) and 32 (30.8%) showed abnormal diagnostic classifications on any of the GCA and RNFL maps, respectively. Multivariate analysis revealed that false-positive GCA diagnostic classification was associated with longer axial length and larger fovea-disc angle, whereas longer axial length and smaller disc area were associated with abnormal RNFL maps. Eyes with abnormal GCA deviation map were categorized as group A (donut-shaped round area around the inner annulus), group B (island-like isolated area), and group C (diffuse, circular area with an irregular inner margin in either). The axial length showed a significant increasing trend from group A to C (P=0.001), and likewise, the refractive error was more myopic in group C than in groups A (P=0.015) and B (P=0.014). Group C had thinner average ganglion cell-inner plexiform layer thickness compared with other groups (group A=B>C, P=0

  18. False-positive rate determination of protein target discovery using a covalent modification- and mass spectrometry-based proteomics platform.

    PubMed

    Strickland, Erin C; Geer, M Ariel; Hong, Jiyong; Fitzgerald, Michael C

    2014-01-01

    Detection and quantitation of protein-ligand binding interactions is important in many areas of biological research. Stability of proteins from rates of oxidation (SPROX) is an energetics-based technique for identifying the proteins targets of ligands in complex biological mixtures. Knowing the false-positive rate of protein target discovery in proteome-wide SPROX experiments is important for the correct interpretation of results. Reported here are the results of a control SPROX experiment in which chemical denaturation data is obtained on the proteins in two samples that originated from the same yeast lysate, as would be done in a typical SPROX experiment except that one sample would be spiked with the test ligand. False-positive rates of 1.2-2.2% and <0.8% are calculated for SPROX experiments using Q-TOF and Orbitrap mass spectrometer systems, respectively. Our results indicate that the false-positive rate is largely determined by random errors associated with the mass spectral analysis of the isobaric mass tag (e.g., iTRAQ®) reporter ions used for peptide quantitation. Our results also suggest that technical replicates can be used to effectively eliminate such false positives that result from this random error, as is demonstrated in a SPROX experiment to identify yeast protein targets of the drug, manassantin A. The impact of ion purity in the tandem mass spectral analyses and of background oxidation on the false-positive rate of protein target discovery using SPROX is also discussed.

  19. Minimizing false positive error with multiple performance validity tests: response to Bilder, Sugar, and Hellemann (2014 this issue).

    PubMed

    Larrabee, Glenn J

    2014-01-01

    Bilder, Sugar, and Hellemann (2014 this issue) contend that empirical support is lacking for use of multiple performance validity tests (PVTs) in evaluation of the individual case, differing from the conclusions of Davis and Millis (2014), and Larrabee (2014), who found no substantial increase in false positive rates using a criterion of failure of ≥ 2 PVTs and/or Symptom Validity Tests (SVTs) out of multiple tests administered. Reconsideration of data presented in Larrabee (2014) supports a criterion of ≥ 2 out of up to 7 PVTs/SVTs, as keeping false positive rates close to and in most cases below 10% in cases with bona fide neurologic, psychiatric, and developmental disorders. Strategies to minimize risk of false positive error are discussed, including (1) adjusting individual PVT cutoffs or criterion for number of PVTs failed, for examinees who have clinical histories placing them at risk for false positive identification (e.g., severe TBI, schizophrenia), (2) using the history of the individual case to rule out conditions known to result in false positive errors, (3) using normal performance in domains mimicked by PVTs to show that sufficient native ability exists for valid performance on the PVT(s) that have been failed, and (4) recognizing that as the number of PVTs/SVTs failed increases, the likelihood of valid clinical presentation decreases, with a corresponding increase in the likelihood of invalid test performance and symptom report.

  20. Biological false-positive venereal disease research laboratory test in cerebrospinal fluid in the diagnosis of neurosyphilis - a case-control study.

    PubMed

    Zheng, S; Lin, R J; Chan, Y H; Ngan, C C L

    2018-03-01

    There is no clear consensus on the diagnosis of neurosyphilis. The Venereal Disease Research Laboratory (VDRL) test from cerebrospinal fluid (CSF) has traditionally been considered the gold standard for diagnosing neurosyphilis but is widely known to be insensitive. In this study, we compared the clinical and laboratory characteristics of true-positive VDRL-CSF cases with biological false-positive VDRL-CSF cases. We retrospectively identified cases of true and false-positive VDRL-CSF across a 3-year period received by the Immunology and Serology Laboratory, Singapore General Hospital. A biological false-positive VDRL-CSF is defined as a reactive VDRL-CSF with a non-reactive Treponema pallidum particle agglutination (TPPA)-CSF and/or negative Line Immuno Assay (LIA)-CSF IgG. A true-positive VDRL-CSF is a reactive VDRL-CSF with a concordant reactive TPPA-CSF and/or positive LIA-CSF IgG. During the study period, a total of 1254 specimens underwent VDRL-CSF examination. Amongst these, 60 specimens from 53 patients tested positive for VDRL-CSF. Of the 53 patients, 42 (79.2%) were true-positive cases and 11 (20.8%) were false-positive cases. In our setting, a positive non-treponemal serology has 97.6% sensitivity, 100% specificity, 100% positive predictive value and 91.7% negative predictive value for a true-positive VDRL-CSF based on our laboratory definition. HIV seropositivity was an independent predictor of a true-positive VDRL-CSF. Biological false-positive VDRL-CSF is common in a setting where patients are tested without first establishing a serological diagnosis of syphilis. Serological testing should be performed prior to CSF evaluation for neurosyphilis. © 2017 European Academy of Dermatology and Venereology.

  1. To Control False Positives in Gene-Gene Interaction Analysis: Two Novel Conditional Entropy-Based Approaches

    PubMed Central

    Lin, Meihua; Li, Haoli; Zhao, Xiaolei; Qin, Jiheng

    2013-01-01

    Genome-wide analysis of gene-gene interactions has been recognized as a powerful avenue to identify the missing genetic components that can not be detected by using current single-point association analysis. Recently, several model-free methods (e.g. the commonly used information based metrics and several logistic regression-based metrics) were developed for detecting non-linear dependence between genetic loci, but they are potentially at the risk of inflated false positive error, in particular when the main effects at one or both loci are salient. In this study, we proposed two conditional entropy-based metrics to challenge this limitation. Extensive simulations demonstrated that the two proposed metrics, provided the disease is rare, could maintain consistently correct false positive rate. In the scenarios for a common disease, our proposed metrics achieved better or comparable control of false positive error, compared to four previously proposed model-free metrics. In terms of power, our methods outperformed several competing metrics in a range of common disease models. Furthermore, in real data analyses, both metrics succeeded in detecting interactions and were competitive with the originally reported results or the logistic regression approaches. In conclusion, the proposed conditional entropy-based metrics are promising as alternatives to current model-based approaches for detecting genuine epistatic effects. PMID:24339984

  2. One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry.

    PubMed

    Marin, Stephanie J; Doyle, Kelly; Chang, Annie; Concheiro-Guisan, Marta; Huestis, Marilyn A; Johnson-Davis, Kamisha L

    2016-01-01

    Some amphetamine (AMP) and ecstacy (MDMA) urine immunoassay (IA) kits are prone to false-positive results due to poor specificity of the antibody. We employed two techniques, high-resolution mass spectrometry (HRMS) and an in silico structure search, to identify compounds likely to cause false-positive results. Hundred false-positive IA specimens for AMP and/or MDMA were analyzed by an Agilent 6230 time-of-flight (TOF) mass spectrometer. Separately, SciFinder (Chemical Abstracts) was used as an in silico structure search to generate a library of compounds that are known to cross-react with AMP/MDMA IAs. Chemical formulas and exact masses of 145 structures were then compared against masses identified by TOF. Compounds known to have cross-reactivity with the IAs were identified in the structure-based search. The chemical formulas and exact masses of 145 structures (of 20 chemical formulas) were compared against masses identified by TOF. Urine analysis by HRMS correlates accurate mass with chemical formulae, but provides little information regarding compound structure. Structural data of targeted antigens can be utilized to correlate HRMS-derived chemical formulas with structural analogs. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. False-positive alarms for bacterial screening of platelet concentrates with BacT/ALERT new-generation plastic bottles: a multicenter pilot study.

    PubMed

    Hundhausen, T; Müller, T H

    2005-08-01

    The microbial detection system BacT/ALERT (bioMérieux) is widely used to monitor bacterial contamination of platelet concentrates (PCs). Recently, the manufacturer introduced polycarbonate culture bottles and a modified pH-sensitive liquid emulsion sensor as microbial growth indicator. This reconfigured assay was investigated in a routine setting. In each of eight transfusion centers, samples from 500 consecutive PCs were monitored for 1 week. For all PCs with a positive BacT/ALERT signal, retained samples and, if available, original PC containers and concomitant red blood cell concentrates were analyzed independently. Initially BacT/ALERT-positive PCs without bacterial identification in any sample were defined as false-positive. BacT/ALERT-positive PCs with bacteria in the first sample only were called potentially positive. PCs with bacteria in the first sample and the same strain in at least one additional sample were accepted as positive. Five PCs (0.13%) were positive, 9 PCs (0.23%) were potentially positive, and 35 PCs (0.9%) were false-positive. The rate of false-positive BacT/ALERT results varied substantially between centers (<0.2%-3.2%). Tracings from false-positive cultures lacked an exponential increase of the signal during incubation. Most of these false-positives were due to malfunctioning cells in various BacT/ALERT incubation units. Careful assessment of individual tracings of samples with positive signals helps to identify malfunctioning incubation units. Their early shutdown or replacement minimizes the high rate of unrectifiable product rejects attributed to false-positive alarms and avoids unnecessary concern of doctors and patients after conversion to a reconfigured BacT/ALERT assay.

  4. Determining Occurrence Dynamics when False Positives Occur: Estimating the Range Dynamics of Wolves from Public Survey Data.

    PubMed

    Miller, David A W; Nichols, James D; Gude, Justin A; Rich, Lindsey N; Podruzny, Kevin M; Hines, James E; Mitchell, Michael S

    2013-01-01

    Large-scale presence-absence monitoring programs have great promise for many conservation applications. Their value can be limited by potential incorrect inferences owing to observational errors, especially when data are collected by the public. To combat this, previous analytical methods have focused on addressing non-detection from public survey data. Misclassification errors have received less attention but are also likely to be a common component of public surveys, as well as many other data types. We derive estimators for dynamic occupancy parameters (extinction and colonization), focusing on the case where certainty can be assumed for a subset of detections. We demonstrate how to simultaneously account for non-detection (false negatives) and misclassification (false positives) when estimating occurrence parameters for gray wolves in northern Montana from 2007-2010. Our primary data source for the analysis was observations by deer and elk hunters, reported as part of the state's annual hunter survey. This data was supplemented with data from known locations of radio-collared wolves. We found that occupancy was relatively stable during the years of the study and wolves were largely restricted to the highest quality habitats in the study area. Transitions in the occupancy status of sites were rare, as occupied sites almost always remained occupied and unoccupied sites remained unoccupied. Failing to account for false positives led to over estimation of both the area inhabited by wolves and the frequency of turnover. The ability to properly account for both false negatives and false positives is an important step to improve inferences for conservation from large-scale public surveys. The approach we propose will improve our understanding of the status of wolf populations and is relevant to many other data types where false positives are a component of observations.

  5. False positive circumsporozoite protein ELISA: a challenge for the estimation of the entomological inoculation rate of malaria and for vector incrimination

    PubMed Central

    2011-01-01

    Background The entomological inoculation rate (EIR) is an important indicator in estimating malaria transmission and the impact of vector control. To assess the EIR, the enzyme-linked immunosorbent assay (ELISA) to detect the circumsporozoite protein (CSP) is increasingly used. However, several studies have reported false positive results in this ELISA. The false positive results could lead to an overestimation of the EIR. The aim of present study was to estimate the level of false positivity among different anopheline species in Cambodia and Vietnam and to check for the presence of other parasites that might interact with the anti-CSP monoclonal antibodies. Methods Mosquitoes collected in Cambodia and Vietnam were identified and tested for the presence of sporozoites in head and thorax by using CSP-ELISA. ELISA positive samples were confirmed by a Plasmodium specific PCR. False positive mosquitoes were checked by PCR for the presence of parasites belonging to the Haemosporidia, Trypanosomatidae, Piroplasmida, and Haemogregarines. The heat-stability and the presence of the cross-reacting antigen in the abdomen of the mosquitoes were also checked. Results Specimens (N = 16,160) of seven anopheline species were tested by CSP-ELISA for Plasmodium falciparum and Plasmodium vivax (Pv210 and Pv247). Two new vector species were identified for the region: Anopheles pampanai (P. vivax) and Anopheles barbirostris (Plasmodium malariae). In 88% (155/176) of the mosquitoes found positive with the P. falciparum CSP-ELISA, the presence of Plasmodium sporozoites could not be confirmed by PCR. This percentage was much lower (28% or 5/18) for P. vivax CSP-ELISAs. False positive CSP-ELISA results were associated with zoophilic mosquito species. None of the targeted parasites could be detected in these CSP-ELISA false positive mosquitoes. The ELISA reacting antigen of P. falciparum was heat-stable in CSP-ELISA true positive specimens, but not in the false positives. The heat

  6. Interval Breast Cancer Rates and Histopathologic Tumor Characteristics after False-Positive Findings at Mammography in a Population-based Screening Program.

    PubMed

    Hofvind, Solveig; Sagstad, Silje; Sebuødegård, Sofie; Chen, Ying; Roman, Marta; Lee, Christoph I

    2018-04-01

    Purpose To compare rates and tumor characteristics of interval breast cancers (IBCs) detected after a negative versus false-positive screening among women participating in the Norwegian Breast Cancer Screening Program. Materials and Methods The Cancer Registry Regulation approved this retrospective study. Information about 423 445 women aged 49-71 years who underwent 789 481 full-field digital mammographic screening examinations during 2004-2012 was extracted from the Cancer Registry of Norway. Rates and odds ratios of IBC among women with a negative (the reference group) versus a false-positive screening were estimated by using logistic regression models adjusted for age at diagnosis and county of residence. Results A total of 1302 IBCs were diagnosed after 789 481 screening examinations, of which 7.0% (91 of 1302) were detected among women with a false-positive screening as the most recent breast imaging examination before detection. By using negative screening as the reference, adjusted odds ratios of IBCs were 3.3 (95% confidence interval [CI]: 2.6, 4.2) and 2.8 (95% CI: 1.8, 4.4) for women with a false-positive screening without and with needle biopsy, respectively. Women with a previous negative screening had a significantly lower proportion of tumors that were 10 mm or less (14.3% [150 of 1049] vs 50.0% [seven of 14], respectively; P < .01) and grade I tumors (13.2% [147 of 1114] vs 42.9% [six of 14]; P < .01), but a higher proportion of cases with lymph nodes positive for cancer (40.9% [442 of 1080] vs 13.3% [two of 15], respectively; P = .03) compared with women with a previous false-positive screening with benign biopsy. A retrospective review of the screening mammographic examinations identified 42.9% (39 of 91) of the false-positive cases to be the same lesion as the IBC. Conclusion By using a negative screening as the reference, a false-positive screening examination increased the risk of an IBC three-fold. The tumor characteristics of IBC after a

  7. The health system impact of false positive newborn screening results for medium-chain acyl-CoA dehydrogenase deficiency: a cohort study.

    PubMed

    Karaceper, Maria D; Chakraborty, Pranesh; Coyle, Doug; Wilson, Kumanan; Kronick, Jonathan B; Hawken, Steven; Davies, Christine; Brownell, Marni; Dodds, Linda; Feigenbaum, Annette; Fell, Deshayne B; Grosse, Scott D; Guttmann, Astrid; Laberge, Anne-Marie; Mhanni, Aizeddin; Miller, Fiona A; Mitchell, John J; Nakhla, Meranda; Prasad, Chitra; Rockman-Greenberg, Cheryl; Sparkes, Rebecca; Wilson, Brenda J; Potter, Beth K

    2016-02-03

    There is no consensus in the literature regarding the impact of false positive newborn screening results on early health care utilization patterns. We evaluated the impact of false positive newborn screening results for medium-chain acyl-CoA dehydrogenase deficiency (MCADD) in a cohort of Ontario infants. The cohort included all children who received newborn screening in Ontario between April 1, 2006 and March 31, 2010. Newborn screening and diagnostic confirmation results were linked to province-wide health care administrative datasets covering physician visits, emergency department visits, and inpatient hospitalizations, to determine health service utilization from April 1, 2006 through March 31, 2012. Incidence rate ratios (IRRs) were used to compare those with false positive results for MCADD to those with negative newborn screening results, stratified by age at service use. We identified 43 infants with a false positive newborn screening result for MCADD during the study period. These infants experienced significantly higher rates of physician visits (IRR: 1.42) and hospitalizations (IRR: 2.32) in the first year of life relative to a screen negative cohort in adjusted analyses. Differences in health services use were not observed after the first year of life. The higher use of some health services among false positive infants during the first year of life may be explained by a psychosocial impact of false positive results on parental perceptions of infant health, and/or by differences in underlying health status. Understanding the impact of false positive newborn screening results can help to inform newborn screening programs in designing support and education for families. This is particularly important as additional disorders are added to expanded screening panels, yielding important clinical benefits for affected children but also a higher frequency of false positive findings.

  8. Chemical applicability domain of the Local Lymph Node Assay (LLNA) for skin sensitisation potency. Part 3. Apparent discrepancies between LLNA and GPMT sensitisation potential: False positives or differences in sensitivity?

    PubMed

    Roberts, David W; Schultz, Terry W; Api, Anne Marie

    2016-10-01

    The Local Lymph Node Assay (LLNA) is the gold standard regulatory toxicology test for skin sensitisation along with the guinea pig maximisation test (GPMT). Compared with the GPMT, LLNA uses fewer animals, it is quantitative, and it gives a numerical prediction of potency. However several concerns have been raised with this assay, mainly related to false positives and false negatives. Over the years, many authors, including the developers of the assay, have presented cases where there have been discrepancies between the GMPT and LLNA results. Several theories have been put forward for these discrepancies, the main one being the "over-sensitivity" of the GPMT. This paper analyses the data from a systematic study, published in three papers from 2008 to 2011, covering several classes of chemicals, in particular unsaturated fatty acids, sugar surfactants and ethoxylated alcohols, with many cases of chemicals testing positive in the LLNA being negative in the GPMT. Based on consideration of reaction chemistry and structural alerts, it is concluded that these discrepancies are not LLNA false positives, but can be rationalised in terms of the different protocols of the assays. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. False positive rate of carbon monoxide saturation by pulse oximetry of emergency department patients.

    PubMed

    Weaver, Lindell K; Churchill, Susan K; Deru, Kayla; Cooney, Darryl

    2013-02-01

    Symptoms of carbon monoxide (CO) poisoning are non-specific. Diagnosis requires suspicion of exposure, confirmed by measuring ambient CO levels or carboxyhemoglobin (COHb). An FDA-approved pulse oximeter (Rad-57) can measure CO saturation (S(pCO)). The device accuracy has implications for clinical decision-making. From April 1 to August 15, 2008, study personnel measured S(pCO) and documented demographic factors at time of clinical blood draw, in a convenience sample of 1,363 subjects presenting to the emergency department at Intermountain Medical Center, Murray, Utah. The technician then assayed COHb. COHb and S(pCO) values were compared by subject; false positive or negative values were defined as S(pCO) at least 3 percentage points greater or less than COHb level, reported by the manufacturer to be ± 1 SD in performance. In 1,363 subjects, 613 (45%) were male, 1,141 (84%) were light-skinned, 14 in shock, 4 with CO poisoning, and 122 (9%) met the criteria for a false positive value (range 3-19 percentage points), while 247 (18%) met the criteria for a false negative value (-13 to -3 percentage points). Risks for a false positive S(pCO) reading included being female and having a lower perfusion index. Methemoglobin, body temperature, and blood pressure also appear to influence the S(pCO) accuracy. There was variability among monitors, possibly related to technician technique, as rotation of monitors among technicians was not enforced. While the Rad-57 pulse oximeter functioned within the manufacturer's specifications, clinicians using the Rad-57 should expect some S(pCO) readings to be significantly higher or lower than COHb measurements, and should not use S(pCO) to direct triage or patient management. An elevated S(pCO) could broaden the diagnosis of CO poisoning in patients with non-specific symptoms. However, a negative S(pCO) level in patients suspected of having CO poisoning should never rule out CO poisoning, and should always be confirmed by COHb. © 2013

  10. How pH, Temperature, and Time of Incubation Affect False-Positive Responses and Uncertainty of the LAL Gel-Clot Test.

    PubMed

    Lourenço, Felipe Rebello; Botelho, Túlia De Souza; Pinto, Terezinha De Jesus Andreoli

    2012-01-01

    The limulus amebocyte lysate (LAL) test is the simplest and most widely used procedure for detection of endotoxin in parenteral drugs. The LAL test demands optimal pH, ionic strength, temperature, and time of incubation. Slight changes in these parameters may increase the frequency of false-positive responses and the estimated uncertainty of the LAL test. The aim of this paper is to evaluate how changes in the pH, temperature, and time of incubation affect the occurrence of false-positive responses in the LAL test. LAL tests were performed in nominal conditions (37 °C, 60 min, and pH 7) and in different conditions of temperature (36 °C and 38 °C), time of incubation (58 and 62 min), and pH (6 and 8). Slight differences in pH increase the frequency of false-positive responses 5-fold (relative risk 5.0), resulting in an estimated of uncertainty 7.6%. Temperature and time of incubation affect the LAL test less, showing relative risks of 1.5 and 1.0, respectively. Estimated uncertainties in 36 °C or 38 °C temperatures and 58 or 62 min of incubation were found to be 2.0% and 1.0%, respectively. Simultaneous differences in these parameters significantly increase the frequency of false-positive responses. The limulus amebocyte lysate (LAL) gel-clot test is a simple test for detection of endotoxin from Gram-negative bacteria. The test is based on a gel formation when a certain amount of endotoxin is present; it is a pass/fail test. The LAL test requires optimal pH, ionic strength, temperature, and time of incubation. Slight difference in these parameters may increase the frequency of false-positive responses. The aim of this paper is to evaluate how changes in the pH, temperature, and time of incubation affect the occurrence of false-positive responses in the LAL test. We find that slight differences in pH increase the frequency of false-positive responses 5-fold. Temperature and time of incubation affect the LAL test less. Simultaneous differences in these parameters

  11. Screening for subclinical Cushing's syndrome in type 2 diabetes mellitus: low false-positive rates with nocturnal salivary cortisol.

    PubMed

    Gagliardi, L; Chapman, I M; O'Loughlin, P; Torpy, D J

    2010-04-01

    The diagnosis of subclinical Cushing's syndrome (SCS) is important, but its relative rarity amongst patients with common metabolic disorders requires a simple test with a low false-positive rate. Using nocturnal salivary cortisol (NSC), which we first validated in patients with suspected and proven Cushing's syndrome, we screened 106 overweight patients with type 2 diabetes mellitus, a group at high risk of SCS and nontumoral hypothalamic-pituitary-adrenal axis perturbations. Our hypothesis was that a lower false-positive rate with NSC was likely, compared with that reported with the dexamethasone suppression test (DST) (10-20%), currently the foundation of diagnosis of SCS. No participant had clinically apparent Cushing's syndrome. Three participants had an elevated NSC but further testing excluded SCS. In this study, NSC had a lower false-positive rate (3%) than previously reported for the DST. Given the reported excellent performance of NSC in detection of hypercortisolism, the low false-positive rate in SCS suggests NSC may be superior to the DST for SCS screening. The NSC and DST should be compared directly in metabolic disorder patients; although our data suggest the patient group will need to be substantially larger to definitively determine the optimal screening test. Georg Thieme Verlag KG Stuttgart New York.

  12. Early Disseminated Lyme Disease Causing False-Positive Serology for Primary Epstein-Barr Virus Infection: Report of 2 Cases.

    PubMed

    Pavletic, Adriana J; Marques, Adriana R

    2017-07-15

    False-positive serology for Lyme disease was reported in patients with acute infectious mononucleosis. Here we describe 2 patients with early disseminated Lyme disease who were misdiagnosed with infectious mononucleosis based on false-positive tests for primary Epstein-Barr virus infection. Published by Oxford University Press for the Infectious Diseases Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  13. False memories, but not false beliefs, affect implicit attitudes for food preferences.

    PubMed

    Howe, David; Anderson, Rachel J; Dewhurst, Stephen A

    2017-09-01

    Previous studies have found that false memories and false beliefs of childhood experiences can have attitudinal consequences. Previous studies have, however, focused exclusively on explicit attitude measures without exploring whether implicit attitudes are similarly affected. Using a false feedback/imagination inflation paradigm, false memories and beliefs of enjoying a certain food as a child were elicited in participants, and their effects were assessed using both explicit attitude measures (self-report questionnaires) and implicit measures (a Single-Target Implicit Association Test). Positive changes in explicit attitudes were observed both in participants with false memories and participants with false beliefs. In contrast, only participants with false memories exhibited more positive implicit attitudes. The findings are discussed in terms of theories of explicit and implicit attitudes. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. False-Positive Cases of Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomographic Scans in Metastasis of Esophageal Cancer

    PubMed Central

    Yamatsuji, Tomoki; Ishida, Naomasa; Takaoka, Munenori; Hayashi, Jiro; Yoshida, Kazuhiro; Shigemitsu, Kaori; Urakami, Atsushi; Haisa, Minoru; Naomoto, Yoshio

    2017-01-01

    Of 129 esophagectomies at our institute from June 2010 to March 2015, we experienced three preoperative positron emission tomography-computed tomographic (PET/CT) false positives. Bone metastasis was originally suspected in 2 cases, but they were later found to be bone metastasis negative after a preoperative bone biopsy and clinical course observation. The other cases suspected of mediastinal lymph node metastasis were diagnosed as inflammatory lymphadenopathy by a pathological examination of the removed lymph nodes. Conducting a PET/CT is useful when diagnosing esophageal cancer metastasis, but we need to be aware of the possibility of false positives. Therapeutic decisions should be made based on appropriate and accurate diagnoses, with pathological diagnosis actively introduced if necessary. PMID:28469502

  15. Restricted Boltzmann machines based oversampling and semi-supervised learning for false positive reduction in breast CAD.

    PubMed

    Cao, Peng; Liu, Xiaoli; Bao, Hang; Yang, Jinzhu; Zhao, Dazhe

    2015-01-01

    The false-positive reduction (FPR) is a crucial step in the computer aided detection system for the breast. The issues of imbalanced data distribution and the limitation of labeled samples complicate the classification procedure. To overcome these challenges, we propose oversampling and semi-supervised learning methods based on the restricted Boltzmann machines (RBMs) to solve the classification of imbalanced data with a few labeled samples. To evaluate the proposed method, we conducted a comprehensive performance study and compared its results with the commonly used techniques. Experiments on benchmark dataset of DDSM demonstrate the effectiveness of the RBMs based oversampling and semi-supervised learning method in terms of geometric mean (G-mean) for false positive reduction in Breast CAD.

  16. Distinguishing Binders from False Positives by Free Energy Calculations: Fragment Screening Against the Flap Site of HIV Protease

    PubMed Central

    2015-01-01

    Molecular docking is a powerful tool used in drug discovery and structural biology for predicting the structures of ligand–receptor complexes. However, the accuracy of docking calculations can be limited by factors such as the neglect of protein reorganization in the scoring function; as a result, ligand screening can produce a high rate of false positive hits. Although absolute binding free energy methods still have difficulty in accurately rank-ordering binders, we believe that they can be fruitfully employed to distinguish binders from nonbinders and reduce the false positive rate. Here we study a set of ligands that dock favorably to a newly discovered, potentially allosteric site on the flap of HIV-1 protease. Fragment binding to this site stabilizes a closed form of protease, which could be exploited for the design of allosteric inhibitors. Twenty-three top-ranked protein–ligand complexes from AutoDock were subject to the free energy screening using two methods, the recently developed binding energy analysis method (BEDAM) and the standard double decoupling method (DDM). Free energy calculations correctly identified most of the false positives (≥83%) and recovered all the confirmed binders. The results show a gap averaging ≥3.7 kcal/mol, separating the binders and the false positives. We present a formula that decomposes the binding free energy into contributions from the receptor conformational macrostates, which provides insights into the roles of different binding modes. Our binding free energy component analysis further suggests that improving the treatment for the desolvation penalty associated with the unfulfilled polar groups could reduce the rate of false positive hits in docking. The current study demonstrates that the combination of docking with free energy methods can be very useful for more accurate ligand screening against valuable drug targets. PMID:25189630

  17. Ignoring Intermarker Linkage Disequilibrium Induces False-Positive Evidence of Linkage for Consanguineous Pedigrees when Genotype Data Is Missing for Any Pedigree Member

    PubMed Central

    Li, Bingshan; Leal, Suzanne M.

    2008-01-01

    Missing genotype data can increase false-positive evidence for linkage when either parametric or nonparametric analysis is carried out ignoring intermarker linkage disequilibrium (LD). Previously it was demonstrated by Huang et al. [1] that no bias occurs in this situation for affected sib-pairs with unrelated parents when either both parents are genotyped or genotype data is available for two additional unaffected siblings when parental genotypes are missing. However, this is not the case for autosomal recessive consanguineous pedigrees, where missing genotype data for any pedigree member within a consanguinity loop can increase false-positive evidence of linkage. False-positive evidence for linkage is further increased when cryptic consanguinity is present. The amount of false-positive evidence for linkage, and which family members aid in its reduction, is highly dependent on which family members are genotyped. When parental genotype data is available, the false-positive evidence for linkage is usually not as strong as when parental genotype data is unavailable. For a pedigree with an affected proband whose first-cousin parents have been genotyped, further reduction in the false-positive evidence of linkage can be obtained by including genotype data from additional affected siblings of the proband or genotype data from the proband's sibling-grandparents. For the situation, when parental genotypes are unavailable, false-positive evidence for linkage can be reduced by including genotype data from either unaffected siblings of the proband or the proband's married-in-grandparents in the analysis. PMID:18073490

  18. Dietary flavonols contribute to false-positive elevation of homovanillic acid, a marker of catecholamine-secreting tumors.

    PubMed

    Combet, Emilie; Lean, Michael E J; Boyle, James G; Crozier, Alan; Davidson, D Fraser

    2011-01-14

    Urinary homovanillic acid (HVA) measurement is used routinely as a marker of the first test for the screening of catecholamine-secreting tumors and dopamine metabolism, but generates a large number of false-positive results. With no guidelines for dietary restrictions prior to the test, we hypothesize that consumption of flavonol-rich foods (such as onions, tomatoes, tea) prior to urinary catecholamine screening could be responsible for false-positive urinary HVA in healthy subjects. A randomized, crossover dietary intervention was carried out in healthy subjects (n=17). Volunteers followed either a low or high-flavonol diet, for a duration of 3 days, prior to providing a 24-h urine sample for HVA measurement using a routine, validated liquid chromatography method as well as a gas chromatography-mass spectrometry method. Dietary flavonol intake significantly increased urinary HVA excretion (p < 0.001), with 3 out of 17 volunteers (20%) exceeding the 40 μmol/24 h upper limit of normal for HVA excretion (false-positive result). Dietary flavonols commonly found in foodstuff such as tomatoes, onions, and tea, interfered with the routine urinary HVA screening test and should be avoided in the three-day run-up to the test. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. False Positives in Multiple Regression: Unanticipated Consequences of Measurement Error in the Predictor Variables

    ERIC Educational Resources Information Center

    Shear, Benjamin R.; Zumbo, Bruno D.

    2013-01-01

    Type I error rates in multiple regression, and hence the chance for false positive research findings, can be drastically inflated when multiple regression models are used to analyze data that contain random measurement error. This article shows the potential for inflated Type I error rates in commonly encountered scenarios and provides new…

  20. A Nested PCR Assay to Avoid False Positive Detection of the Microsporidian Enterocytozoon hepatopenaei (EHP) in Environmental Samples in Shrimp Farms

    PubMed Central

    Jaroenlak, Pattana; Sanguanrut, Piyachat; Williams, Bryony A. P.; Stentiford, Grant D.; Flegel, Timothy W.; Sritunyalucksana, Kallaya

    2016-01-01

    Hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) is an important disease of cultivated shrimp. Heavy infections may lead to retarded growth and unprofitable harvests. Existing PCR detection methods target the EHP small subunit ribosomal RNA (SSU rRNA) gene (SSU-PCR). However, we discovered that they can give false positive test results due to cross reactivity of the SSU-PCR primers with DNA from closely related microsporidia that infect other aquatic organisms. This is problematic for investigating and monitoring EHP infection pathways. To overcome this problem, a sensitive and specific nested PCR method was developed for detection of the spore wall protein (SWP) gene of EHP (SWP-PCR). The new SWP-PCR method did not produce false positive results from closely related microsporidia. The first PCR step of the SWP-PCR method was 100 times (104 plasmid copies per reaction vial) more sensitive than that of the existing SSU-PCR method (106 copies) but sensitivity was equal for both in the nested step (10 copies). Since the hepatopancreas of cultivated shrimp is not currently known to be infected with microsporidia other than EHP, the SSU-PCR methods are still valid for analyzing hepatopancreatic samples despite the lower sensitivity than the SWP-PCR method. However, due to its greater specificity and sensitivity, we recommend that the SWP-PCR method be used to screen for EHP in feces, feed and environmental samples for potential EHP carriers. PMID:27832178

  1. A Nested PCR Assay to Avoid False Positive Detection of the Microsporidian Enterocytozoon hepatopenaei (EHP) in Environmental Samples in Shrimp Farms.

    PubMed

    Jaroenlak, Pattana; Sanguanrut, Piyachat; Williams, Bryony A P; Stentiford, Grant D; Flegel, Timothy W; Sritunyalucksana, Kallaya; Itsathitphaisarn, Ornchuma

    2016-01-01

    Hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) is an important disease of cultivated shrimp. Heavy infections may lead to retarded growth and unprofitable harvests. Existing PCR detection methods target the EHP small subunit ribosomal RNA (SSU rRNA) gene (SSU-PCR). However, we discovered that they can give false positive test results due to cross reactivity of the SSU-PCR primers with DNA from closely related microsporidia that infect other aquatic organisms. This is problematic for investigating and monitoring EHP infection pathways. To overcome this problem, a sensitive and specific nested PCR method was developed for detection of the spore wall protein (SWP) gene of EHP (SWP-PCR). The new SWP-PCR method did not produce false positive results from closely related microsporidia. The first PCR step of the SWP-PCR method was 100 times (104 plasmid copies per reaction vial) more sensitive than that of the existing SSU-PCR method (106 copies) but sensitivity was equal for both in the nested step (10 copies). Since the hepatopancreas of cultivated shrimp is not currently known to be infected with microsporidia other than EHP, the SSU-PCR methods are still valid for analyzing hepatopancreatic samples despite the lower sensitivity than the SWP-PCR method. However, due to its greater specificity and sensitivity, we recommend that the SWP-PCR method be used to screen for EHP in feces, feed and environmental samples for potential EHP carriers.

  2. A False Positive Dengue Fever Rapid Diagnostic Test Result in a Case of Acute Parvovirus B19 Infection.

    PubMed

    Izumida, Toshihide; Sakata, Hidenao; Nakamura, Masahiko; Hayashibara, Yumiko; Inasaki, Noriko; Inahata, Ryo; Hasegawa, Sumiyo; Takizawa, Takenori; Kaya, Hiroyasu

    2016-01-01

    An outbreak of dengue fever occurred in Japan in August 2014. We herein report the case of a 63-year-old man who presented with a persistent fever in September 2014. Acute parvovirus B19 infection led to a false positive finding of dengue fever on a rapid diagnostic test (Panbio Dengue Duo Cassette(TM)). To the best of our knowledge, there are no previous reports of a false positive result for dengue IgM with the dengue rapid diagnostic test. We believe that epidemiological information on the prevalence of parvovirus B19 is useful for guiding the interpretation of a positive result with the dengue rapid diagnostic test.

  3. Skin irritability to sodium lauryl sulfate is associated with increased positive patch test reactions.

    PubMed

    Schwitulla, J; Brasch, J; Löffler, H; Schnuch, A; Geier, J; Uter, W

    2014-07-01

    As previous observations have indicated an inter-relationship between irritant and allergic skin reactions we analysed data of synchronous allergen and sodium lauryl sulfate (SLS) patch tests in terms of a relationship between SLS responsiveness and allergic patch test reactions. To analyse differences in terms of allergen-specific and overall reaction profiles between patients with vs. those without an irritant reaction to SLS. Clinical data of 26 879 patients patch tested from 2008 to 2011 by members of the Information Network of Departments of Dermatology were analysed. After descriptive analyses, including the MOAHLFA index, the positivity ratio and the reaction index, a negative binomial hurdle model was adopted to investigate the correlation between SLS reactivity and positive patch test reactions. Men, patients aged ≥ 40 years and patients with an occupational dermatitis background were over-represented in the SLS-reactive group. Patients with an irritant reaction to SLS showed a higher proportion of weak positive reactions, as well as more questionable and irritant reactions to contact allergens than patients not reactive to SLS. The risk of an additional positive patch test reaction increased by 22% for SLS-reactive patients compared with those who were SLS negative. The marked association between SLS reactivity and the number of positive reactions in patch test patients may be due to nonspecific increased skin reactivity at the moment of patch testing only. However, increased SLS reactivity could also be due to longer-lasting enhanced skin irritability, which may have promoted (poly-)sensitization. Further studies, for example with longitudinal data on patients repeatedly patch tested with SLS and contact allergens, are necessary. © 2014 British Association of Dermatologists.

  4. Clinical relevance of positive patch test reactions to the 26 EU-labelled fragrances.

    PubMed

    van Oosten, Eleonoor J; Schuttelaar, Marie-Louise A; Coenraads, Pieter Jan

    2009-10-01

    Fragrance mix I (FM I) and fragrance mix II (FM II) in the European baseline series are used as screening tools for fragrance contact allergy. In 2005 the European Union (EU) required labelling of 26 fragrances when present in cosmetic products. INCI nomenclature is obligatory for such labelling. To describe frequencies of contact allergy to these 26 fragrance substances, and to evaluate clinical relevance of these positive reactions. Three hundred and twenty patients with eczema suspected of being contact allergy to fragrances or cosmetics were patch tested with the EU-declared fragrance chemicals, FM I and FM II. There were 76 positive reactions in 33 patients. Most reactions were seen to [corrected] hydroxyisohexyl 3-cyclohexene carboxaldehyde in 3.1%, followed by Evernia furfuracea (2.5%) and cinnamyl alcohol (2.5%). Twelve reactions to FM I and II were not confirmed by separate ingredients. Clinical relevance of positive reactions to fragrances was certain in 20/33 (61%). 10.3% of the patients had positive patch tests in the EU-list. Hydroxyisohexyl 3-cyclohexene carboxaldehyde, a component of FM II, was the most frequent allergen, followed by Evernia furfuracea. Since Evernia furfuracea is not part of FM I or FM II, relevant reactions can be missed when only the European baseline series is used.

  5. Inflammatory disorders mimicking periprosthetic joint infections may result in false positive α-defensin.

    PubMed

    Plate, Andreas; Stadler, Laura; Sutter, Reto; Anagnostopoulos, Alexia; Frustaci, Dario; Zbinden, Reinhard; Fucentese, Sandro F; Zinkernagel, Annelies S; Zingg, Patrick O; Achermann, Yvonne

    2018-02-26

    The antimicrobial peptide α-defensin has recently been introduced as potential "single" biomarker with a high sensitivity and specificity for the preoperative diagnosis of periprosthetic joint infections (PJIs). However, most studies assessed the benefits of the test with exclusion of patients with rheumatic diseases. We aimed to evaluate the α-defensin test in a cohort study without exclusion of cases with inflammatory diseases. Between June 2016 and June 2017, we prospectively included cases with a suspected PJI and an available lateral flow test α-defensin (Synovasure®) in synovial fluid. We compared the test result to the diagnostic criteria for PJIs published by an International Consensus Group in 2013. We included 109 cases (49 hips, 60 knees) in which preoperative α-defensin tests had been performed. Thereof, 20 PJIs (16 hips, 4 knees) were diagnosed. Preoperative α-defensin tests were positive in 25 cases (22.9%) with a test sensitivity and specificity of 90% and 92.1% (95% confidence interval [CI], 68.3 - 98.8% and 84.5 - 96.8%, respectively), and a high negative predictive value of 97.6% (95% CI, 91.7 - 99.4%). We interpreted seven α-defensin tests as false positive, mainly in cases with inflammatory rheumatic diseases, including crystal deposition diseases. A negative synovial α-defensin test can reliably rule out a PJI. However, the test can be false positive in conjunction with an underlying non-infectious inflammatory disease. We therefore propose to use the α-defensin test only in addition to MSIS criteria and assessment for crystals in synovial aspirates. Copyright © 2018. Published by Elsevier Ltd.

  6. [False positive result in mammography and its association with the presence of obesity: a case-control study].

    PubMed

    Castro-Ibarra, Marisela; Menchaca-Díaz, Rufino; Cabrales-Ruvalcaba, J Jesús; Luna-V Gómez, Rosa Alicia

    2016-01-01

    To analyze the association between a false positive result in mammography and obesity, inside the breast cancer early detection program in women affiliated to the Institute of Security and Social Services for Government and Municipality workers of the State of Baja California (ISSSTECALI). A case-control, retrospective study was done in women affiliated to ISSSTECALI to whom a mammography was performed between 2009 and 2012. Women with a false positive result in mammography were included as cases. Controls were women with a true negative result in mammography. Three controls were randomly selected for each case. Obesity was established with the body mass index (BMI) consigned in the woman's clinical file. Age and estrogen replacement therapy were included as co-variables. Seventy nine cases were identified and 237 controls were included. Obesity was observed in 54.4% of cases and in 41.3% of controls (odds ratio: 1.69; 95% confidence interval for odds ratio: 1.01-2.82; p value: 0.043). A logistic regression model including covariables maintained the observed association (p = 0.044). No association was found with analyzed co-variables. A false positive result in mammography was associated with the presence of obesity.

  7. Classification of radiological errors in chest radiographs, using support vector machine on the spatial frequency features of false- negative and false-positive regions

    NASA Astrophysics Data System (ADS)

    Pietrzyk, Mariusz W.; Donovan, Tim; Brennan, Patrick C.; Dix, Alan; Manning, David J.

    2011-03-01

    Aim: To optimize automated classification of radiological errors during lung nodule detection from chest radiographs (CxR) using a support vector machine (SVM) run on the spatial frequency features extracted from the local background of selected regions. Background: The majority of the unreported pulmonary nodules are visually detected but not recognized; shown by the prolonged dwell time values at false-negative regions. Similarly, overestimated nodule locations are capturing substantial amounts of foveal attention. Spatial frequency properties of selected local backgrounds are correlated with human observer responses either in terms of accuracy in indicating abnormality position or in the precision of visual sampling the medical images. Methods: Seven radiologists participated in the eye tracking experiments conducted under conditions of pulmonary nodule detection from a set of 20 postero-anterior CxR. The most dwelled locations have been identified and subjected to spatial frequency (SF) analysis. The image-based features of selected ROI were extracted with un-decimated Wavelet Packet Transform. An analysis of variance was run to select SF features and a SVM schema was implemented to classify False-Negative and False-Positive from all ROI. Results: A relative high overall accuracy was obtained for each individually developed Wavelet-SVM algorithm, with over 90% average correct ratio for errors recognition from all prolonged dwell locations. Conclusion: The preliminary results show that combined eye-tracking and image-based features can be used for automated detection of radiological error with SVM. The work is still in progress and not all analytical procedures have been completed, which might have an effect on the specificity of the algorithm.

  8. Do one-time intracompartmental pressure measurements have a high false-positive rate in diagnosing compartment syndrome?

    PubMed

    Whitney, Augusta; O'Toole, Robert V; Hui, Emily; Sciadini, Marcus F; Pollak, Andrew N; Manson, Theodore T; Eglseder, W Andrew; Andersen, Romney C; Lebrun, Christopher; Doro, Christopher; Nascone, Jason W

    2014-02-01

    Intracompartmental pressure measurements are frequently used in the diagnosis of compartment syndrome, particularly in patients with equivocal or limited physical examination findings. Little clinical work has been done to validate the clinical use of intracompartmental pressures or identify associated false-positive rates. We hypothesized that diagnosis of compartment syndrome based on one-time pressure measurements alone is associated with a high false-positive rate. Forty-eight consecutive patients with tibial shaft fractures who were not suspected of having compartment syndrome based on physical examinations were prospectively enrolled. Pressure measurements were obtained in all four compartments at a single point in time immediately after induction of anesthesia using a pressure-monitoring device. Preoperative and intraoperative blood pressure measurements were recorded. The same standardized examination was performed by the attending surgeon preoperatively, postoperatively, and during clinical follow-up for 6 months to assess clinical evidence of acute or late compartment syndrome. No clinical evidence of compartment syndrome was observed postoperatively or during follow-up until 6 months after injury. Using the accepted criteria of delta P of 30 mm Hg from preoperative diastolic blood pressure, 35% of cases (n = 16; 95% confidence interval, 21.5-48.5%) met criteria for compartment syndrome. Raising the threshold to delta P of 20 mm Hg reduced the false-positive rate to 24% (n = 11; 95% confidence interval, 11.1-34.9%). Twenty-two percent (n = 10; 95% confidence interval, 9.5-32.5%) exceeded absolute pressure of 45 mm Hg. A 35% false-positive rate was found for the diagnosis of compartment syndrome in patients with tibial shaft fractures who were not thought to have compartment syndrome by using currently accepted criteria for diagnosis based solely on one-time compartment pressure measurements. Our data suggest that reliance on one-time intracompartmental

  9. All That Glisters Is Not Gold: Sampling-Process Uncertainty in Disease-Vector Surveys with False-Negative and False-Positive Detections

    PubMed Central

    Abad-Franch, Fernando; Valença-Barbosa, Carolina; Sarquis, Otília; Lima, Marli M.

    2014-01-01

    Background Vector-borne diseases are major public health concerns worldwide. For many of them, vector control is still key to primary prevention, with control actions planned and evaluated using vector occurrence records. Yet vectors can be difficult to detect, and vector occurrence indices will be biased whenever spurious detection/non-detection records arise during surveys. Here, we investigate the process of Chagas disease vector detection, assessing the performance of the surveillance method used in most control programs – active triatomine-bug searches by trained health agents. Methodology/Principal Findings Control agents conducted triplicate vector searches in 414 man-made ecotopes of two rural localities. Ecotope-specific ‘detection histories’ (vectors or their traces detected or not in each individual search) were analyzed using ordinary methods that disregard detection failures and multiple detection-state site-occupancy models that accommodate false-negative and false-positive detections. Mean (±SE) vector-search sensitivity was ∼0.283±0.057. Vector-detection odds increased as bug colonies grew denser, and were lower in houses than in most peridomestic structures, particularly woodpiles. False-positive detections (non-vector fecal streaks misidentified as signs of vector presence) occurred with probability ∼0.011±0.008. The model-averaged estimate of infestation (44.5±6.4%) was ∼2.4–3.9 times higher than naïve indices computed assuming perfect detection after single vector searches (11.4–18.8%); about 106–137 infestation foci went undetected during such standard searches. Conclusions/Significance We illustrate a relatively straightforward approach to addressing vector detection uncertainty under realistic field survey conditions. Standard vector searches had low sensitivity except in certain singular circumstances. Our findings suggest that many infestation foci may go undetected during routine surveys, especially when vector

  10. A FALSE POSITIVE FOR OCEAN GLINT ON EXOPLANETS: THE LATITUDE-ALBEDO EFFECT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cowan, Nicolas B.; Abbot, Dorian S.; Voigt, Aiko

    2012-06-10

    Identifying liquid water on the surface of planets is a high priority, as this traditionally defines habitability. One proposed signature of oceans is specular reflection ('glint'), which increases the apparent albedo of a planet at crescent phases. We post-process a global climate model of an Earth-like planet to simulate reflected light curves. Significantly, we obtain glint-like phase variations even though we do not include specular reflection in our model. This false positive is the product of two generic properties: (1) for modest obliquities, a planet's poles receive less orbit-averaged stellar flux than its equator, so the poles are more likelymore » to be covered in highly reflective snow and ice; and (2) we show that reflected light from a modest-obliquity planet at crescent phases probes higher latitudes than at gibbous phases, therefore a planet's apparent albedo will naturally increase at crescent phase. We suggest that this 'latitude-albedo effect' will operate even for large obliquities: in that case the equator receives less orbit-averaged flux than the poles, and the equator is preferentially sampled at crescent phase. Using rotational and orbital color variations to map the surfaces of directly imaged planets and estimate their obliquity will therefore be a necessary pre-condition for properly interpreting their reflected phase variations. The latitude-albedo effect is a particularly convincing glint false positive for zero-obliquity planets, and such worlds are not amenable to latitudinal mapping. This effect severely limits the utility of specular reflection for detecting oceans on exoplanets.« less

  11. Are Hemorrhoids Associated with False-Positive Fecal Immunochemical Test Results?

    PubMed

    Kim, Nam Hee; Park, Jung Ho; Park, Dong Il; Sohn, Chong Il; Choi, Kyuyong; Jung, Yoon Suk

    2017-01-01

    False-positive (FP) results of fecal immunochemical tests (FITs) conducted in colorectal cancer (CRC) screening could lead to performing unnecessary colonoscopies. Hemorrhoids are a possible cause of FP FIT results; however, studies on this topic are extremely rare. We investigated whether hemorrhoids are associated with FP FIT results. A retrospective study was conducted at a university hospital in Korea from June 2013 to May 2015. Of the 34547 individuals who underwent FITs, 3946 aged ≥50 years who underwent colonoscopies were analyzed. Logistic regression analysis was performed to determine factors associated with FP FIT results. Among 3946 participants, 704 (17.8%) showed positive FIT results and 1303 (33.0%) had hemorrhoids. Of the 704 participants with positive FIT results, 165 had advanced colorectal neoplasia (ACRN) and 539 had no ACRN (FP results). Of the 1303 participants with hemorrhoids, 291 showed FP results, of whom 81 showed FP results because of hemorrhoids only. Participants with hemorrhoids had a higher rate of FP results than those without hemorrhoids (291/1176, 24.7% vs. 248/2361, 10.5%; p<0.001). Additionally, the participants with hemorrhoids as the only abnormality had a higher rate of FP results than those experiencing no such abnormalities (81/531, 15.3% vs. 38/1173, 3.2%; p<0.001). In multivariate analysis, the presence of hemorrhoids was identified as an independent predictor of FP results (adjusted odds ratio, 2.76; 95% confidence interval, 2.24-3.40; p<0.001). Hemorrhoids are significantly associated with FP FIT results. Their presence seemed to be a non-negligible contributor of FP results in FIT-based CRC screening programs.

  12. Are Hemorrhoids Associated with False-Positive Fecal Immunochemical Test Results?

    PubMed Central

    Kim, Nam Hee; Park, Jung Ho; Park, Dong Il; Sohn, Chong Il; Choi, Kyuyong

    2017-01-01

    Purpose False-positive (FP) results of fecal immunochemical tests (FITs) conducted in colorectal cancer (CRC) screening could lead to performing unnecessary colonoscopies. Hemorrhoids are a possible cause of FP FIT results; however, studies on this topic are extremely rare. We investigated whether hemorrhoids are associated with FP FIT results. Materials and Methods A retrospective study was conducted at a university hospital in Korea from June 2013 to May 2015. Of the 34547 individuals who underwent FITs, 3946 aged ≥50 years who underwent colonoscopies were analyzed. Logistic regression analysis was performed to determine factors associated with FP FIT results. Results Among 3946 participants, 704 (17.8%) showed positive FIT results and 1303 (33.0%) had hemorrhoids. Of the 704 participants with positive FIT results, 165 had advanced colorectal neoplasia (ACRN) and 539 had no ACRN (FP results). Of the 1303 participants with hemorrhoids, 291 showed FP results, of whom 81 showed FP results because of hemorrhoids only. Participants with hemorrhoids had a higher rate of FP results than those without hemorrhoids (291/1176, 24.7% vs. 248/2361, 10.5%; p<0.001). Additionally, the participants with hemorrhoids as the only abnormality had a higher rate of FP results than those experiencing no such abnormalities (81/531, 15.3% vs. 38/1173, 3.2%; p<0.001). In multivariate analysis, the presence of hemorrhoids was identified as an independent predictor of FP results (adjusted odds ratio, 2.76; 95% confidence interval, 2.24–3.40; p<0.001). Conclusion Hemorrhoids are significantly associated with FP FIT results. Their presence seemed to be a non-negligible contributor of FP results in FIT-based CRC screening programs. PMID:27873508

  13. Prenatal Ultrasound Screening: False Positive Soft Markers May Alter Maternal Representations and Mother-Infant Interaction

    PubMed Central

    Viaux-Savelon, Sylvie; Dommergues, Marc; Rosenblum, Ouriel; Bodeau, Nicolas; Aidane, Elizabeth; Philippon, Odile; Mazet, Philippe; Vibert-Guigue, Claude; Vauthier-Brouzes, Danièle; Feldman, Ruth; Cohen, David

    2012-01-01

    Background In up to 5% of pregnancies, ultrasound screening detects a “soft marker” (SM) that places the foetus at risk for a severe abnormality. In most cases, prenatal diagnostic work-up rules out a severe defect. We aimed to study the effects of false positive SM on maternal emotional status, maternal representations of the infant, and mother-infant interaction. Methodology and Principal Findings Utilizing an extreme-case prospective case control design, we selected from a group of 244 women undergoing ultrasound, 19 pregnant women whose foetus had a positive SM screening and a reassuring diagnostic work up, and 19 controls without SM matched for age and education. In the third trimester of pregnancy, within one week after delivery, and 2 months postpartum, we assessed anxiety, depression, and maternal representations. Mother-infant interactions were videotaped during feeding within one week after delivery and again at 2 months postpartum and coded blindly using the Coding Interactive Behavior (CIB) scales. Anxiety and depression scores were significantly higher at all assessment points in the SM group. Maternal representations were also different between SM and control groups at all study time. Perturbations to early mother-infant interactions were observed in the SM group. These dyads showed greater dysregulation, lower maternal sensitivity, higher maternal intrusive behaviour and higher infant avoidance. Multivariate analysis showed that maternal representation and depression at third trimester predicted mother-infant interaction. Conclusion False positive ultrasound screenings for SM are not benign and negatively affect the developing maternal-infant attachment. Medical efforts should be directed to minimize as much as possible such false diagnoses, and to limit their psychological adverse consequences. PMID:22292077

  14. Reduction of lymph tissue false positives in pulmonary embolism detection

    NASA Astrophysics Data System (ADS)

    Ghanem, Bernard; Liang, Jianming; Bi, Jinbo; Salganicoff, Marcos; Krishnan, Arun

    2008-03-01

    Pulmonary embolism (PE) is a serious medical condition, characterized by the partial/complete blockage of an artery within the lungs. We have previously developed a fast yet effective approach for computer aided detection of PE in computed topographic pulmonary angiography (CTPA),1 which is capable of detecting both acute and chronic PEs, achieving a benchmark performance of 78% sensitivity at 4 false positives (FPs) per volume. By reviewing the FPs generated by this system, we found the most dominant type of FP, roughly one third of all FPs, to be lymph/connective tissue. In this paper, we propose a novel approach that specifically aims at reducing this FP type. Our idea is to explicitly exploit the anatomical context configuration of PE and lymph tissue in the lungs: a lymph FP connects to the airway and is located outside the artery, while a true PE should not connect to the airway and must be inside the artery. To realize this idea, given a detected candidate (i.e. a cluster of suspicious voxels), we compute a set of contextual features, including its distance to the airway based on local distance transform and its relative position to the artery based on fast tensor voting and Hessian "vesselness" scores. Our tests on unseen cases show that these features can reduce the lymph FPs by 59%, while improving the overall sensitivity by 3.4%.

  15. The clinical impact of a false-positive urine cocaine screening result on a patient's pain management.

    PubMed

    Kim, James A; Ptolemy, Adam S; Melanson, Stacy E F; Janfaza, David R; Ross, Edgar L

    2015-06-01

    The urine of a patient admitted for chest and epigastric pain tested positive for cocaine using an immunoassay-based drug screening method (positive/negative cutoff concentration 150 ng/mL). Despite the patient's denial of recent cocaine use, this positive cocaine screening result in conjunction with a remote history of drug misuse impacted the patient's recommended pain therapy. Specifically, these factors prompted the clinical team to question the appropriateness of opioids and other potentially addictive therapeutics during the treatment of cancer pain from previously undetected advanced pancreatic carcinoma. After pain management and clinical pathology consultation, it was decided that the positive cocaine screening result should be confirmed by gas chromatography-mass spectrometry (GC-MS) testing. This more sensitive and specific analytical technique revealed that both cocaine and its primary metabolite benzoylecgonine were undetectable (i.e., less than the assay detection limit of 50 ng/mL), thus indicating that the positive urine screening result was falsely positive. With this confirmation, the pain management service team was reassured in offering intrathecal pump (ITP) therapy for pain control. ITP implantation was well tolerated, and the patient eventually achieved excellent pain relief. However, ITP therapy most likely would not have been utilized without the GC-MS confirmation testing unless alternative options failed and extensive vigilant monitoring was initiated. As exemplified in this case, confirmatory drug testing should be performed on specimens with unexpected immunoassay-based drug screening results. To our knowledge, this is the first report of a false-positive urine cocaine screening result and its impact on patient management. Wiley Periodicals, Inc.

  16. Silastic injection for vocal fold medialization resulting in a false-positive finding on F18 FDG-PET/CT.

    PubMed

    Mahfouz, Ayman; Naji, Meeran; Mok, Wing Yan; Taghi, Ali S; Win, Zarni

    2015-09-01

    A false-positive uptake of F18-fluorodeoxyglucose (FDG) on positron-emission tomography/computed tomography (PET/CT) can result in confusion and misinterpretation of scans. Such uptakes have been previously described after injection of polytetrafluoroethylene (Teflon) into the vocal folds. Similarly, vocal fold injection of silicone elastomer (Silastic) can result not only in a false-positive FDG uptake on PET/CT, but also in chronic inflammation. We report a case of increased FDG uptake in a vocal fold after Silastic injection that was misinterpreted as a malignancy in a 70-year-old woman who had metastatic carcinoma of the stomach.

  17. Efficient detection of human circulating tumor cells without significant production of false-positive cells by a novel conditionally replicating adenovirus

    PubMed Central

    Sakurai, Fuminori; Narii, Nobuhiro; Tomita, Kyoko; Togo, Shinsaku; Takahashi, Kazuhisa; Machitani, Mitsuhiro; Tachibana, Masashi; Ouchi, Masaaki; Katagiri, Nobuyoshi; Urata, Yasuo; Fujiwara, Toshiyoshi; Mizuguchi, Hiroyuki

    2016-01-01

    Circulating tumor cells (CTCs) are promising biomarkers in several cancers, and thus methods and apparatuses for their detection and quantification in the blood have been actively pursued. A novel CTC detection system using a green fluorescence protein (GFP)–expressing conditionally replicating adenovirus (Ad) (rAd-GFP) was recently developed; however, there is concern about the production of false-positive cells (GFP-positive normal blood cells) when using rAd-GFP, particularly at high titers. In addition, CTCs lacking or expressing low levels of coxsackievirus–adenovirus receptor (CAR) cannot be detected by rAd-GFP, because rAd-GFP is constructed based on Ad serotype 5, which recognizes CAR. In order to suppress the production of false-positive cells, sequences perfectly complementary to blood cell–specific microRNA, miR-142-3p, were incorporated into the 3′-untranslated region of the E1B and GFP genes. In addition, the fiber protein was replaced with that of Ad serotype 35, which recognizes human CD46, creating rAdF35-142T-GFP. rAdF35-142T-GFP efficiently labeled not only CAR-positive tumor cells but also CAR-negative tumor cells with GFP. The numbers of false-positive cells were dramatically lower for rAdF35-142T-GFP than for rAd-GFP. CTCs in the blood of cancer patients were detected by rAdF35-142T-GFP with a large reduction in false-positive cells. PMID:26966699

  18. Infectious mononucleosis complicated by acute haemolytic anaemia with a positive Donath-Landsteiner reaction

    PubMed Central

    Wishart, M. M.; Davey, M. G.

    1973-01-01

    A patient with infectious mononucleosis complicated by acute haemolytic anaemia is described. The patient had, in addition to non-specific cold agglutinins in the serum, a positive Donath-Landsteiner reaction in the absence of syphilis. The association of a positive Donath-Landsteiner reaction with haemolytic anaemia in infectious mononucleosis has been described only once before. PMID:4714957

  19. Relevance of cutoff on a 4th generation ELISA performance in the false positive rate during HIV diagnostic in a low HIV prevalence setting.

    PubMed

    Chacón, Lucía; Mateos, María Luisa; Holguín, África

    2017-07-01

    Despite the high specificity of fourth-generation enzyme immunoassays (4th-gen-EIA) for screening during HIV diagnosis, their positive predictive value is low in populations with low HIV prevalence. Thus, screening should be optimized to reduce false positive results. The influence of sample cutoff (S/CO) values by a 4th-gen-EIA with the false positive rate during the routine HIV diagnosis in a low HIV prevalence population was evaluated. A total of 30,201 sera were tested for HIV diagnosis using Abbott Architect ® HIV-Ag/Ab-Combo 4th-gen-EIA at a hospital in Spain during 17 months. Architect S/CO values were recorded, comparing the HIV-1 positive results following Architect interpretation (S/CO≥1) with the final HIV-1 diagnosis by confirmatory tests (line immunoassay, LIA and/or nucleic acid test, NAT). ROC curve was also performed. Among the 30,201 HIV performed tests, 256 (0.85%) were positive according to Architect interpretation (S/CO≥1) but only 229 (0.76%) were definitively HIV-1 positive after LIA and/or NAT. Thus, 27 (10.5%) of 256 samples with S/CO≥1 by Architect were false positive diagnose. The false positive rate decreased when the S/CO ratio increased. All 19 samples with S/CO ≤10 were false positives and all 220 with S/CO>50 true HIV-positives. The optimal S/CO cutoff value provided by ROC curves was 32.7. No false negative results were found. We show that very low S/CO values during HIV-1 screening using Architect can result HIV negative after confirmation by LIA and NAT. The false positive rate is reduced when S/CO increases. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. False-Positive Head-Impulse Test in Cerebellar Ataxia

    PubMed Central

    Kremmyda, Olympia; Kirchner, Hanni; Glasauer, Stefan; Brandt, Thomas; Jahn, Klaus; Strupp, Michael

    2012-01-01

    The objective of this study was to compare the findings of the bedside head-impulse test (HIT), passive head rotation gain, and caloric irrigation in patients with cerebellar ataxia (CA). In 16 patients with CA and bilaterally pathological bedside HIT, vestibuloocular reflex (VOR) gains were measured during HIT and passive head rotation by scleral search coil technique. Eight of the patients had pathologically reduced caloric responsiveness, while the other eight had normal caloric responses. Those with normal calorics showed a slightly reduced HIT gain (mean ± SD: 0.73 ± 0.15). In those with pathological calorics, gains 80 and 100 ms after the HIT as well as the passive rotation VOR gains were significantly lower. The corrective saccade after head turn occurred earlier in patients with pathological calorics (111 ± 62 ms after onset of the HIT) than in those with normal calorics (191 ± 17 ms, p = 0.0064). We identified two groups of patients with CA: those with an isolated moderate HIT deficit only, probably due to floccular dysfunction, and those with combined HIT, passive rotation, and caloric deficit, probably due to a peripheral vestibular deficit. From a clinical point of view, these results show that the bedside HIT alone can be false-positive for establishing a diagnosis of a bilateral peripheral vestibular deficit in patients with CA. PMID:23162531

  1. Robust Correlation Analyses: False Positive and Power Validation Using a New Open Source Matlab Toolbox

    PubMed Central

    Pernet, Cyril R.; Wilcox, Rand; Rousselet, Guillaume A.

    2012-01-01

    Pearson’s correlation measures the strength of the association between two variables. The technique is, however, restricted to linear associations and is overly sensitive to outliers. Indeed, a single outlier can result in a highly inaccurate summary of the data. Yet, it remains the most commonly used measure of association in psychology research. Here we describe a free Matlab(R) based toolbox (http://sourceforge.net/projects/robustcorrtool/) that computes robust measures of association between two or more random variables: the percentage-bend correlation and skipped-correlations. After illustrating how to use the toolbox, we show that robust methods, where outliers are down weighted or removed and accounted for in significance testing, provide better estimates of the true association with accurate false positive control and without loss of power. The different correlation methods were tested with normal data and normal data contaminated with marginal or bivariate outliers. We report estimates of effect size, false positive rate and power, and advise on which technique to use depending on the data at hand. PMID:23335907

  2. Robust correlation analyses: false positive and power validation using a new open source matlab toolbox.

    PubMed

    Pernet, Cyril R; Wilcox, Rand; Rousselet, Guillaume A

    2012-01-01

    Pearson's correlation measures the strength of the association between two variables. The technique is, however, restricted to linear associations and is overly sensitive to outliers. Indeed, a single outlier can result in a highly inaccurate summary of the data. Yet, it remains the most commonly used measure of association in psychology research. Here we describe a free Matlab((R)) based toolbox (http://sourceforge.net/projects/robustcorrtool/) that computes robust measures of association between two or more random variables: the percentage-bend correlation and skipped-correlations. After illustrating how to use the toolbox, we show that robust methods, where outliers are down weighted or removed and accounted for in significance testing, provide better estimates of the true association with accurate false positive control and without loss of power. The different correlation methods were tested with normal data and normal data contaminated with marginal or bivariate outliers. We report estimates of effect size, false positive rate and power, and advise on which technique to use depending on the data at hand.

  3. Cross-reactivity between Lyme and syphilis screening assays: Lyme disease does not cause false-positive syphilis screens.

    PubMed

    Patriquin, Glenn; LeBlanc, Jason; Heinstein, Charles; Roberts, Catherine; Lindsay, Robbin; Hatchette, Todd F

    2016-03-01

    Increased rates of Lyme disease and syphilis in the same geographic area prompted an assessment of screening test cross-reactivity. This study supports the previously described cross-reactivity of Lyme screening among syphilis-positive sera and reports evidence against the possibility of false-positive syphilis screening tests resulting from previous Borrelia burgdorferi infection. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. False-positive cryptococcal antigen test associated with use of BBL Port-a-Cul transport vials.

    PubMed

    Wilson, Deborah A; Sholtis, Mary; Parshall, Sharon; Hall, Gerri S; Procop, Gary W

    2011-02-01

    A total of 52 residual CSF and serum specimens, which were originally negative with the Cryptococcal Antigen Latex Agglutination System (CALAS), were shown to become falsely positive after placement in BBL Port-A-Cul anaerobic transport vials. This transport device, although excellent for specimen transportation for subsequent culture, should not be used if cryptococcal antigen testing is needed.

  5. Similarity based false-positive reduction for breast cancer using radiographic and pathologic imaging features

    NASA Astrophysics Data System (ADS)

    Pai, Akshay; Samala, Ravi K.; Zhang, Jianying; Qian, Wei

    2010-03-01

    Mammography reading by radiologists and breast tissue image interpretation by pathologists often leads to high False Positive (FP) Rates. Similarly, current Computer Aided Diagnosis (CADx) methods tend to concentrate more on sensitivity, thus increasing the FP rates. A novel method is introduced here which employs similarity based method to decrease the FP rate in the diagnosis of microcalcifications. This method employs the Principal Component Analysis (PCA) and the similarity metrics in order to achieve the proposed goal. The training and testing set is divided into generalized (Normal and Abnormal) and more specific (Abnormal, Normal, Benign) classes. The performance of this method as a standalone classification system is evaluated in both the cases (general and specific). In another approach the probability of each case belonging to a particular class is calculated. If the probabilities are too close to classify, the augmented CADx system can be instructed to have a detailed analysis of such cases. In case of normal cases with high probability, no further processing is necessary, thus reducing the computation time. Hence, this novel method can be employed in cascade with CADx to reduce the FP rate and also avoid unnecessary computational time. Using this methodology, a false positive rate of 8% and 11% is achieved for mammography and cellular images respectively.

  6. False-Positive Tuberculin Skin Test Results Among Low-Risk Healthcare Workers Following Implementation of Fifty-Dose Vials of Purified Protein Derivative.

    PubMed

    Collins, Jeffrey M; Hunter, Mary; Gordon, Wanda; Kempker, Russell R; Blumberg, Henry M; Ray, Susan M

    2018-06-01

    Following large declines in tuberculosis transmission the United States, large-scale screening programs targeting low-risk healthcare workers are increasingly a source of false-positive results. We report a large cluster of presumed false-positive tuberculin skin test results in healthcare workers following a change to 50-dose vials of Tubersol tuberculin.Infect Control Hosp Epidemiol 2018;39:750-752.

  7. Marine Bacteria Cause False-Positive Results in the Colilert-18 Rapid Identification Test for Escherichia coli in Florida Waters

    PubMed Central

    Pisciotta, John M.; Rath, Damon F.; Stanek, Paul A.; Flanery, D. Michael; Harwood, Valerie J.

    2002-01-01

    The Colilert-18 system for enumeration of total coliforms and Escherichia coli is approved by the U.S. Environmental Protection Agency for use in drinking water analysis and is also used by various agencies and research studies for enumeration of indicator organisms in fresh and saline waters. During monitoring of Pinellas County, Fla., marine waters, estimates of E. coli numbers (by Colilert-18) frequently exceeded fecal coliform counts (by membrane filtration) by 1 to 3 orders of magnitude. Samples from freshwater sites did not display similar discrepancies. Fecal coliforms, including E. coli, could be cultured from 100% of yellow fluorescent wells (denoting E. coli-positive results) inoculated with freshwater samples but could be cultured from only 17.1% of the “positive” wells inoculated with marine samples. Ortho-nitrophenyl-β-d-galactopyranoside (ONPG)-positive or 4-methylumbelliferyl-β-d-glucuronide (MUG)-positive noncoliform bacteria were readily cultured from Colilert-18 test wells inoculated with marine samples. Filtered cell-free seawater did not cause false positives. Coculture preparations of as few as 5 CFU of Vibrio cholerae (ONPG positive) and Providencia sp. (MUG positive) ml−1 inoculated into Colilert-18 caused false-positive E. coli results. Salinity conditions influenced coculture results, as the concentration of coculture inoculum required to cause false positives in most wells increased from about 5 CFU ml−1 in seawater diluted 1:10 with freshwater to ≈5,000 CFU ml−1 in seawater diluted 1:20 with freshwater. Estimated E. coli numbers in various marine water samples processed at the 1:10 dilution ranged from 10 to 7,270 CFU·100 ml−1, while E. coli numbers in the same samples processed at the 1:20 dilution did not exceed 40 CFU·100 ml−1. The lower estimates of E. coli numbers corresponded well with fecal coliform counts by membrane filtration. This study indicates that assessment of E. coli in subtropical marine waters by

  8. [Roaming through methodology. XXXII. False test results].

    PubMed

    van der Weijden, T; van den Akker, M

    2001-05-12

    The number of requests for diagnostic tests is rising. This leads to a higher chance of false test results. The false-negative proportion of a test is the proportion of negative test results among the diseased subjects. The false-positive proportion is the proportion of positive test results among the healthy subjects. The calculation of the false-positive proportion is often incorrect. For example, instead of 1 minus the specificity it is calculated as 1 minus the positive predictive value. This can lead to incorrect decision-making with respect to the application of the test. Physicians must apply diagnostic tests in such a way that the risk of false test results is minimal. The patient should be aware that a perfectly conclusive diagnostic test is rare in medical practice, and should more often be informed of the implications of false-positive and false-negative test results.

  9. Between-litter variation in developmental studies of hormones and behavior: Inflated false positives and diminished power.

    PubMed

    Williams, Donald R; Carlsson, Rickard; Bürkner, Paul-Christian

    2017-10-01

    Developmental studies of hormones and behavior often include littermates-rodent siblings that share early-life experiences and genes. Due to between-litter variation (i.e., litter effects), the statistical assumption of independent observations is untenable. In two literatures-natural variation in maternal care and prenatal stress-entire litters are categorized based on maternal behavior or experimental condition. Here, we (1) review both literatures; (2) simulate false positive rates for commonly used statistical methods in each literature; and (3) characterize small sample performance of multilevel models (MLM) and generalized estimating equations (GEE). We found that the assumption of independence was routinely violated (>85%), false positives (α=0.05) exceeded nominal levels (up to 0.70), and power (1-β) rarely surpassed 0.80 (even for optimistic sample and effect sizes). Additionally, we show that MLMs and GEEs have adequate performance for common research designs. We discuss implications for the extant literature, the field of behavioral neuroendocrinology, and provide recommendations. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Hormone replacement therapy and false positive recall in the Million Women Study: patterns of use, hormonal constituents and consistency of effect

    PubMed Central

    Banks, Emily; Reeves, Gillian; Beral, Valerie; Bull, Diana; Crossley, Barbara; Simmonds, Moya; Hilton, Elizabeth; Bailey, Stephen; Barrett, Nigel; Briers, Peter; English, Ruth; Jackson, Alan; Kutt, Elizabeth; Lavelle, Janet; Rockall, Linda; Wallis, Matthew G; Wilson, Mary; Patnick, Julietta

    2006-01-01

    Introduction Current and recent users of hormone replacement therapy (HRT) have an increased risk of being recalled to assessment at mammography without breast cancer being diagnosed ('false positive recall'), but there is limited information on the effects of different patterns of HRT use on this. The aim of this study is to investigate in detail the relationship between patterns of use of HRT and false positive recall. Methods A total of 87,967 postmenopausal women aged 50 to 64 years attending routine breast cancer screening at 10 UK National Health Service Breast Screening Units from 1996 to 1998 joined the Million Women Study by completing a questionnaire before screening and were followed for their screening outcome. Results Overall, 399 (0.5%) participants were diagnosed with breast cancer and 2,629 (3.0%) had false positive recall. Compared to never users of HRT, the adjusted relative risk (95% CI) of false positive recall was: 1.62 (1.43–1.83), 1.80 (1.62–2.01) and 0.76 (0.52–1.10) in current users of oestrogen-only HRT, oestrogen-progestagen HRT and tibolone, respectively (p (heterogeneity) < 0.0001); 1.65 (1.43–1.91), 1.49 (1.22–1.81) and 2.11 (1.45–3.07) for current HRT used orally, transdermally or via an implant, respectively (p (heterogeneity) = 0.2); and 1.84 (1.67–2.04) and 1.75 (1.49–2.06) for sequential and continuous oestrogen-progestagen HRT, respectively (p (heterogeneity) = 0.6). The relative risk of false positive recall among current users appeared to increase with increasing time since menopause, but did not vary significantly according to any other factors examined, including duration of use, hormonal constituents, dose, whether single- or two-view screening was used, or the woman's personal characteristics. Conclusion Current use of oestrogen-only and oestrogen-progestagen HRT, but not tibolone, increases the risk of false positive recall at screening. PMID:16417651

  11. Verification of clinical samples, positive in AMPLICOR Neisseria gonorrhoeae polymerase chain reaction, by 16S rRNA and gyrA compared with culture.

    PubMed

    Airell, Asa; Lindbäck, Emma; Ataker, Ferda; Pörnull, Kirsti Jalakas; Wretlind, Bengt

    2005-06-01

    We compared 956 samples for AMPLICOR Neisseria gonorrhoeae polymerase chain reaction (PCR) (Roche) with species verification using the 16S rRNA gene to verification using gyrA gene. Control was the culture method. The gyrA verification uses pyrosequencing of the quinolone resistance-determining region of gyrA. Of 52 samples with optical density >/=0.2 in PCR, 27 were negative in culture, two samples from pharynx were false negative in culture and four samples from pharynx were false positives in verification with 16S rRNA. Twenty-five samples showed growth of gonococci, 18 of the corresponding PCR samples were verified by both methods; three urine samples were positive only in gyrA ; and one pharynx specimen was positive only in 16S rRNA. Three samples were lost. We conclude that AMPLICOR N. gonorrhoeae PCR with verification in gyrA gene can be considered as a diagnostic tool in populations with low prevalence of gonorrhoea and that pharynx specimens should not be analysed by PCR.

  12. False-Positive Cryptococcal Antigen Test Associated with Use of BBL Port-A-Cul Transport Vials▿

    PubMed Central

    Wilson, Deborah A.; Sholtis, Mary; Parshall, Sharon; Hall, Gerri S.; Procop, Gary W.

    2011-01-01

    A total of 52 residual CSF and serum specimens, which were originally negative with the Cryptococcal Antigen Latex Agglutination System (CALAS), were shown to become falsely positive after placement in BBL Port-A-Cul anaerobic transport vials. This transport device, although excellent for specimen transportation for subsequent culture, should not be used if cryptococcal antigen testing is needed. PMID:21159939

  13. IS HCI THAT IS USED AS A PRESERVATIVE CREATING FALSE POSITIVES FOR TBA IN GROUND WATER

    EPA Science Inventory

    Will hydrochloric acid produce false positives for TBA? Yes, if you heat the sample to get a lower detection limit for TBA. Conventional purge and trap methods at ambient temperature have a reporting limit for TBA between 50 and 100 g/liter. This is higher than the provisiona...

  14. Finding False Positives Planet Candidates Due To Background Eclipsing Binaries in K2

    NASA Astrophysics Data System (ADS)

    Mullally, Fergal; Thompson, Susan E.; Coughlin, Jeffrey; DAVE Team

    2016-06-01

    We adapt the difference image centroid approach, used for finding background eclipsing binaries, to vet K2 planet candidates. Difference image centroids were used with great success to vet planet candidates in the original Kepler mission, where the source of a transit could be identified by subtracting images of out-of-transit cadences from in-transit cadences. To account for K2's roll pattern, we reconstruct out-of-transit images from cadences that are nearby in both time and spacecraft roll angle. We describe the method and discuss some K2 planet candidates which this method suggests are false positives.

  15. Comparing Positively and Negatively Charged Distonic Radical Ions in Phenylperoxyl Forming Reactions.

    PubMed

    Williams, Peggy E; Marshall, David L; Poad, Berwyck L J; Narreddula, Venkateswara R; Kirk, Benjamin B; Trevitt, Adam J; Blanksby, Stephen J

    2018-06-04

    In the gas phase, arylperoxyl forming reactions play a significant role in low-temperature combustion and atmospheric processing of volatile organic compounds. We have previously demonstrated the application of charge-tagged phenyl radicals to explore the outcomes of these reactions using ion trap mass spectrometry. Here, we present a side-by-side comparison of rates and product distributions from the reaction of positively and negatively charge tagged phenyl radicals with dioxygen. The negatively charged distonic radical ions are found to react with significantly greater efficiency than their positively charged analogues. The product distributions of the anion reactions favor products of phenylperoxyl radical decomposition (e.g., phenoxyl radicals and cyclopentadienone), while the comparable fixed-charge cations yield the stabilized phenylperoxyl radical. Electronic structure calculations rationalize these differences as arising from the influence of the charged moiety on the energetics of rate-determining transition states and reaction intermediates within the phenylperoxyl reaction manifold and predict that this influence could extend to intra-molecular charge-radical separations of up to 14.5 Å. Experimental observations of reactions of the novel 4-(1-carboxylatoadamantyl)phenyl radical anion confirm that the influence of the charge on both rate and product distribution can be modulated by increasing the rigidly imposed separation between charge and radical sites. These findings provide a generalizable framework for predicting the influence of charged groups on polarizable radicals in gas phase distonic radical ions. Graphical Abstract.

  16. Comparing Positively and Negatively Charged Distonic Radical Ions in Phenylperoxyl Forming Reactions

    NASA Astrophysics Data System (ADS)

    Williams, Peggy E.; Marshall, David L.; Poad, Berwyck L. J.; Narreddula, Venkateswara R.; Kirk, Benjamin B.; Trevitt, Adam J.; Blanksby, Stephen J.

    2018-06-01

    In the gas phase, arylperoxyl forming reactions play a significant role in low-temperature combustion and atmospheric processing of volatile organic compounds. We have previously demonstrated the application of charge-tagged phenyl radicals to explore the outcomes of these reactions using ion trap mass spectrometry. Here, we present a side-by-side comparison of rates and product distributions from the reaction of positively and negatively charge tagged phenyl radicals with dioxygen. The negatively charged distonic radical ions are found to react with significantly greater efficiency than their positively charged analogues. The product distributions of the anion reactions favor products of phenylperoxyl radical decomposition (e.g., phenoxyl radicals and cyclopentadienone), while the comparable fixed-charge cations yield the stabilized phenylperoxyl radical. Electronic structure calculations rationalize these differences as arising from the influence of the charged moiety on the energetics of rate-determining transition states and reaction intermediates within the phenylperoxyl reaction manifold and predict that this influence could extend to intra-molecular charge-radical separations of up to 14.5 Å. Experimental observations of reactions of the novel 4-(1-carboxylatoadamantyl)phenyl radical anion confirm that the influence of the charge on both rate and product distribution can be modulated by increasing the rigidly imposed separation between charge and radical sites. These findings provide a generalizable framework for predicting the influence of charged groups on polarizable radicals in gas phase distonic radical ions.

  17. Impacting the effect of fMRI noise through hardware and acquisition choices - Implications for controlling false positive rates.

    PubMed

    Wald, Lawrence L; Polimeni, Jonathan R

    2017-07-01

    We review the components of time-series noise in fMRI experiments and the effect of image acquisition parameters on the noise. In addition to helping determine the total amount of signal and noise (and thus temporal SNR), the acquisition parameters have been shown to be critical in determining the ratio of thermal to physiological induced noise components in the time series. Although limited attention has been given to this latter metric, we show that it determines the degree of spatial correlations seen in the time-series noise. The spatially correlations of the physiological noise component are well known, but recent studies have shown that they can lead to a higher than expected false-positive rate in cluster-wise inference based on parametric statistical methods used by many researchers. Based on understanding the effect of acquisition parameters on the noise mixture, we propose several acquisition strategies that might be helpful reducing this elevated false-positive rate, such as moving to high spatial resolution or using highly-accelerated acquisitions where thermal sources dominate. We suggest that the spatial noise correlations at the root of the inflated false-positive rate problem can be limited with these strategies, and the well-behaved spatial auto-correlation functions (ACFs) assumed by the conventional statistical methods are retained if the high resolution data is smoothed to conventional resolutions. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Patients with breakthrough reactions to iodinated contrast media have low incidence of positive skin tests.

    PubMed

    Berti, A; Della-Torre, E; Yacoub, Mr; Tombetti, E; Canti, V; Sabbadini, M G; Colombo, G

    2016-07-01

    The term "breakthrough reactions" designates repeated hypersensitivity reactions to iodinated contrast media (ICM) despite premedication with glucocorticoids and antihistamines. We aimed to retrospectively evaluate the rate of positive skin test (STs) in our cohort of patients with previous breakthrough reactions to different ICMs. A series of 35 patients, who experienced at least one breakthrough reaction to ICM and who underwent STs within 6 months from the reaction were studied, and results were compared to a control group of patients with a first hypersensitivity reaction occurred without premedication. Skin prick tests (SPT), intradermal tests (IDT) and patch tests (PT) at different dilutions, with a set of three to four ICM were performed. Of the 35 patients with prior breakthrough reactions, 57% had an immediate reaction (IR) and 43% had a non-immediate reaction (NIR). Patients who experienced the first hypersensitivity IR or NIR, later had one or more breakthrough IR or NIR, respectively. Overall, 29% (10/35) of patients with prior breakthrough reactions resulted positive to STs compared to 57% (16/28) of the control group (p < 0.05). No significant difference in allergy history, age, sex, other clinical / demographic features nor chronic use of ACE-inhibitor, beta-blockers or NSAIDs was observed. This preliminary finding suggests that patients with prior breakthrough reactions have significantly lower immunologically proven ICM reactions (positive STs) if compared to non-breakthrough patients. According to that, a considerable number of breakthrough reactions seems to be non-allergic hypersensitivity reactions or reactions which could be mostly prevented by a proper, well-timed skin testing. Larger prospective studies are needed to confirm these results, with a more careful analysis of patients' risk factors, a laboratory assessment that includes an in vitro allergy diagnostics, and hopefully a drug provocation test for selected cases.

  19. Frequency of false positive rapid HIV serologic tests in African men and women receiving PrEP for HIV prevention: implications for programmatic roll-out of biomedical interventions.

    PubMed

    Ndase, Patrick; Celum, Connie; Kidoguchi, Lara; Ronald, Allan; Fife, Kenneth H; Bukusi, Elizabeth; Donnell, Deborah; Baeten, Jared M

    2015-01-01

    Rapid HIV assays are the mainstay of HIV testing globally. Delivery of effective biomedical HIV prevention strategies such as antiretroviral pre-exposure prophylaxis (PrEP) requires periodic HIV testing. Because rapid tests have high (>95%) but imperfect specificity, they are expected to generate some false positive results. We assessed the frequency of true and false positive rapid results in the Partners PrEP Study, a randomized, placebo-controlled trial of PrEP. HIV testing was performed monthly using 2 rapid tests done in parallel with HIV enzyme immunoassay (EIA) confirmation following all positive rapid tests. A total of 99,009 monthly HIV tests were performed; 98,743 (99.7%) were dual-rapid HIV negative. Of the 266 visits with ≥1 positive rapid result, 99 (37.2%) had confirmatory positive EIA results (true positives), 155 (58.3%) had negative EIA results (false positives), and 12 (4.5%) had discordant EIA results. In the active PrEP arms, over two-thirds of visits with positive rapid test results were false positive results (69.2%, 110 of 159), although false positive results occurred at <1% (110/65,945) of total visits. When HIV prevalence or incidence is low due to effective HIV prevention interventions, rapid HIV tests result in a high number of false relative to true positive results, although the absolute number of false results will be low. Program roll-out for effective interventions should plan for quality assurance of HIV testing, mechanisms for confirmatory HIV testing, and counseling strategies for persons with positive rapid test results.

  20. Detecting and avoiding likely false-positive findings - a practical guide.

    PubMed

    Forstmeier, Wolfgang; Wagenmakers, Eric-Jan; Parker, Timothy H

    2017-11-01

    Recently there has been a growing concern that many published research findings do not hold up in attempts to replicate them. We argue that this problem may originate from a culture of 'you can publish if you found a significant effect'. This culture creates a systematic bias against the null hypothesis which renders meta-analyses questionable and may even lead to a situation where hypotheses become difficult to falsify. In order to pinpoint the sources of error and possible solutions, we review current scientific practices with regard to their effect on the probability of drawing a false-positive conclusion. We explain why the proportion of published false-positive findings is expected to increase with (i) decreasing sample size, (ii) increasing pursuit of novelty, (iii) various forms of multiple testing and researcher flexibility, and (iv) incorrect P-values, especially due to unaccounted pseudoreplication, i.e. the non-independence of data points (clustered data). We provide examples showing how statistical pitfalls and psychological traps lead to conclusions that are biased and unreliable, and we show how these mistakes can be avoided. Ultimately, we hope to contribute to a culture of 'you can publish if your study is rigorous'. To this end, we highlight promising strategies towards making science more objective. Specifically, we enthusiastically encourage scientists to preregister their studies (including a priori hypotheses and complete analysis plans), to blind observers to treatment groups during data collection and analysis, and unconditionally to report all results. Also, we advocate reallocating some efforts away from seeking novelty and discovery and towards replicating important research findings of one's own and of others for the benefit of the scientific community as a whole. We believe these efforts will be aided by a shift in evaluation criteria away from the current system which values metrics of 'impact' almost exclusively and towards a system

  1. Breaking through the false coincidence barrier in electron–ion coincidence experiments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Osborn, David L.; Hayden, Carl C.; Hemberger, Patrick

    Photoelectron Photoion Coincidence (PEPICO) spectroscopy holds the promise of a universal, isomer-selective, and sensitive analytical technique for time-resolved quantitative analysis of bimolecular chemical reactions. Unfortunately, its low dynamic range of ~10 3 has largely precluded its use for this purpose, where a dynamic range of at least 10 5 is generally required. This limitation is due to the false coincidence background common to all coincidence experiments, especially at high count rates. Electron/ion pairs emanating from separate ionization events but arriving within the ion time of flight (TOF) range of interest constitute the false coincidence background. Although this background has uniformmore » intensity at every m/z value, the Poisson scatter in the false coincidence background obscures small signals. In this paper, temporal ion deflection coupled with a position-sensitive ion detector enables suppression of the false coincidence background, increasing the dynamic range in the PEPICO TOF mass spectrum by 2–3 orders of magnitude. The ions experience a time-dependent electric deflection field at a well-defined fraction of their time of flight. This deflection defines an m/z- and ionization-time dependent ion impact position for true coincidences, whereas false coincidences appear randomly outside this region and can be efficiently suppressed. When cold argon clusters are ionized, false coincidence suppression allows us to observe species up to Ar 9 +, whereas Ar 4 + is the largest observable cluster under traditional operation. As a result, this advance provides mass-selected photoelectron spectra for fast, high sensitivity quantitative analysis of reacting systems.« less

  2. Breaking through the false coincidence barrier in electron–ion coincidence experiments

    DOE PAGES

    Osborn, David L.; Hayden, Carl C.; Hemberger, Patrick; ...

    2016-10-31

    Photoelectron Photoion Coincidence (PEPICO) spectroscopy holds the promise of a universal, isomer-selective, and sensitive analytical technique for time-resolved quantitative analysis of bimolecular chemical reactions. Unfortunately, its low dynamic range of ~10 3 has largely precluded its use for this purpose, where a dynamic range of at least 10 5 is generally required. This limitation is due to the false coincidence background common to all coincidence experiments, especially at high count rates. Electron/ion pairs emanating from separate ionization events but arriving within the ion time of flight (TOF) range of interest constitute the false coincidence background. Although this background has uniformmore » intensity at every m/z value, the Poisson scatter in the false coincidence background obscures small signals. In this paper, temporal ion deflection coupled with a position-sensitive ion detector enables suppression of the false coincidence background, increasing the dynamic range in the PEPICO TOF mass spectrum by 2–3 orders of magnitude. The ions experience a time-dependent electric deflection field at a well-defined fraction of their time of flight. This deflection defines an m/z- and ionization-time dependent ion impact position for true coincidences, whereas false coincidences appear randomly outside this region and can be efficiently suppressed. When cold argon clusters are ionized, false coincidence suppression allows us to observe species up to Ar 9 +, whereas Ar 4 + is the largest observable cluster under traditional operation. As a result, this advance provides mass-selected photoelectron spectra for fast, high sensitivity quantitative analysis of reacting systems.« less

  3. Sequencing from dried blood spots in infants with "false positive" newborn screen for MCAD deficiency.

    PubMed

    McCandless, Shawn E; Chandrasekar, Ram; Linard, Sharon; Kikano, Sandra; Rice, Lorrie

    2013-01-01

    Newborn screening (NBS) for medium chain acyl-CoA dehydrogenase deficiency (MCADD), one of the most common disorders identified, uses measurement of octanoylcarnitine (C8) from dried blood spots. In the state of Ohio, as in many places, primary care providers, with or without consultation from a metabolic specialist, may perform "confirmatory testing", with the final diagnostic decision returned to the state. Confirmatory testing may involve measurement of metabolites, enzyme analysis, mutation screening, or sequencing. We now report sequencing results for infants said to have "false positive" NBS results for MCAD deficiency, or who died before confirmatory testing could be performed. Dried blood spots (DBS) were obtained from all 18 available NBS cards identified as "false positive" by NBS for the 3 year period after screening began in Ohio in 2003 (N=20, thus 2 had no DBS available), and from all 6 infants with abnormal screens who died before confirmatory testing could be obtained. DNA extracted from DBS was screened for the common c.985A>G mutation in exon 11 of the ACADM gene, using a specific restriction digest method, followed by sequencing of the 12 exons, intron-exon junctions, and several hundred base pairs of the 5' untranslated region. The NBS cut-off value for C8 used was 0.7 μmol/L. Sequencing of ACADM in six neonates with elevated C8 on NBS who died before confirmatory testing was obtained did not identify any significant variants in the coding region of the gene, suggesting that MCADD was not a contributing factor in these deaths. The mean C8 for the 18 surviving infants labeled as "False Positives" was 0.90 (95%CI 0.77-1.15), much lower than the mean value for confirmed cases. Ten of the 18 were premature births weighing <1200 g, the rest were normal sized and full term. Eight infants, mostly full term with appropriate birth weight, were heterozygous for the common c.985A>G mutation; one of those also has a novel sequence change identified in exon

  4. Placing symptoms in context: the role of contextual criteria in reducing false positives in Diagnostic and Statistical Manual of Mental Disorders diagnoses.

    PubMed

    Wakefield, Jerome C; First, Michael B

    2012-02-01

    The Diagnostic and Statistical Manual of Mental Disorders (DSM) definition of mental disorder requires that symptoms be caused by a dysfunction in the individual; when dysfunction is absent, symptoms represent normal-range distress or eccentricity and, if diagnosed as a mental disorder, are false positives. We hypothesized that because of psychiatry's lack of direct laboratory tests to distinguish dysfunction from normal-range distress, the context in which symptoms occur (eg, lack of imminent danger in a panic attack) is often essential to determining whether symptoms are caused by a dysfunction. If this is right, then the DSM diagnostic criteria should include many contextual criteria added to symptom syndromes to prevent dysfunction false positives. Despite their potential importance, such contextual criteria have not been previously reviewed. We, thus, systematically reviewed DSM categories to establish the extent of such uses of contextual criteria and created a typology of such uses. Of 111 sampled categories, 68 (61%) used context to prevent dysfunction false positives. Contextual criteria fell into 7 types: (1) exclusion of specific false-positive scenarios; (2) requiring that patients experience preconditions for normal responses (eg, requiring that individuals experience adequate sexual stimulation before being diagnosed with sexual dysfunctions); (3) requiring that symptoms be disproportionate relative to circumstances; (4) for childhood disorders, requiring that symptoms be developmentally inappropriate; (5) requiring that symptoms occur in multiple contexts; (6) requiring a substantial discrepancy between beliefs and reality; and (7) a residual category. Most DSM categories include contextual criteria to eliminate false-positive diagnoses and increase validity of descriptive criteria. Future revisions should systematically evaluate each category's need for contextual criteria. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Likelihood of early detection of breast cancer in relation to false-positive risk in life-time mammographic screening: population-based cohort study.

    PubMed

    Otten, J D M; Fracheboud, J; den Heeten, G J; Otto, S J; Holland, R; de Koning, H J; Broeders, M J M; Verbeek, A L M

    2013-10-01

    Women require balanced, high-quality information when making an informed decision on screening benefits and harms before attending biennial mammographic screening. The cumulative risk of a false-positive recall and/or (small) screen-detected or interval cancer over 13 consecutive screening examinations for women aged 50 from the start of screening were estimated using data from the Nijmegen programme, the Netherlands. Women who underwent 13 successive screens in the period 1975-1976 had a 5.3% cumulative chance of a screen-detected cancer, with a 4.2% risk of at least one false-positive recall. The risk of being diagnosed with interval cancer was 3.7%. Two decades later, these estimates were 6.9%, 7.3% and 2.9%, respectively. The chance of detection of a small, favourable invasive breast cancer, anticipating a normal life-expectancy, rose from 2.3% to 3.7%. Extrapolation to digital screening mammography indicates that the proportion of false-positive results will rise to 16%. Dutch women about to participate in the screening programme can be reassured that the chance of false-positive recall in the Netherlands is relatively low. A new screening policy and improved mammography have increased the detection of an early screening carcinoma and lowering the risk of interval carcinoma.

  6. Kepler False Positive Rate & Occurrence of Earth-size and Larger Planets

    NASA Astrophysics Data System (ADS)

    Fressin, Francois; Torres, G.; Charbonneau, D.; Kepler Team

    2013-01-01

    We model the Kepler exoplanet survey targets and their background stars to estimate the occurrence of astrophysical configurations which could mimic an exoplanetary transit. Using real noise level estimates, we compute the number and the characteristics of detectable eclipsing pairs involving stars or planets. We select the fraction of those that would pass the Kepler candidate vetting procedure, including the modeling of the centroid shift of their position on the Kepler camera. By comparing their distribution with that of the Kepler Object Interests from the first 6 quarters of Kepler data, we quantify the false positive rate of Kepler, as a function of candidate planet size and period. Most importantly, this approach allows quantifying and characterizing the distribution of planets, with no assumption of any prior, as the remaining population of the Kepler candidate list minus the simulated population of alternate astrophysical causes. We study the actual detection recovery rate for Kepler that allows reproducing both the KOI size and period distribution as well as their SNR distribution. We estimate the occurrence of planets down to Earth-size, and study if their frequency is correlated with their host star spectral type. This work is supported by the Spitzer General Observer Proposal #80117 - Validating the First Habitable-Zone Planet Candidates Identified by the NASA Kepler Mission, and by the Kepler Participating Scientist Contract led by David Charbonneau, to confirm the planetary nature of candidates identified by the Kepler mission

  7. Transient ST segment depression during Holter monitoring: how to avoid false positive findings.

    PubMed

    Völler, H; Andresen, D; Brüggemann, T; Jereczek, M; Becker, B; Schröder, R

    1992-09-01

    To increase the specificity of 24-hour Holter monitoring in detecting transient myocardial ischemia, we separated genuine ST deviations from those dependent on artifacts by adding a detailed shape analysis of real-time printouts to the usual criteria of significant ST segment depression. We screened 116 apparently healthy subjects; 31 had to be excluded, because of pathologic findings in preliminary examinations. The remaining 85 (49 women and 36 men; mean age, 43.1 years) underwent Holter monitoring for assessment of the extent, frequency, and duration of episodes of horizontal and descending ST segment depression of at least 0.1 mV that persisted for at least 60 msec after the J point and that were at least 1 minute apart. On the basis of these criteria, six subjects (7.1%) showed 24 episodes of horizontal or descending ST segment depression with a mean of 0.2 mV (range, 0.15 to 0.25 mV), a frequency of four episodes per 24 hours (one to nine), and a duration of 12.2 minutes (range 3-range 41 minutes). Supplementary criteria--e.g., sudden onset of ST segment depression, identical orientation of PQ and ST segments, or simultaneous increase in R and P wave amplitude--made it possible to identify ST changes caused by artifacts in four volunteers. In only two subjects (2.4%) could true silent ischemia not be differentiated from false positive results. Thus consideration of only the extent, frequency, and duration of episodes does not permit a differentiation between true silent ischemia and false positive results. A supplementary shape analysis increases the specificity of ST segment analysis in detecting transient myocardial ischemia during 24-hour Holter monitoring.

  8. Interpreting the results of the Semmes-Weinstein monofilament test: accounting for false-positive answers in the international consensus on the diabetic foot protocol by a new model.

    PubMed

    Slater, Robert A; Koren, Shlomit; Ramot, Yoram; Buchs, Andreas; Rapoport, Micha J

    2014-01-01

    The Semmes-Weinstein monofilament is the most widely used test to diagnose the loss of protective sensation. The commonly used protocol of the International Consensus on the Diabetic Foot includes a 'sham' application that allows for false-positive answers. We sought to study the heretofore unexamined significance of false-positive answers. Forty-five patients with diabetes and a history of pedal ulceration (Group I) and 81 patients with diabetes but no history of ulceration (Group II) were studied. The three original sites of the International Consensus on the Diabetic Foot at the hallux, 1st metatarsal and 5th metatarsal areas were used. At each location, the test was performed three times: 2 actual and 1 "sham" applications. Scores were graded from 0 to 3 based upon correct responses. Determination of loss of protective sensation was performed with and without calculating a false-positive answer as a minus 1 score. False-positive responses were found in a significant percentage of patients with and without history of ulceration. Introducing false-positive results as minus 1 into the test outcome significantly increased the number of patients diagnosed with loss of protective sensation in both groups. False-positive answers can significantly affect Semmes-Weinstein monofilament test results and the diagnosis of LOPS. A model that accounts for false-positive answers is offered. Copyright © 2013 John Wiley & Sons, Ltd.

  9. False positive indium-111 white blood cell scan in a closed clavicle fracture

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Friedman, R.J.; Gordon, L.

    1988-01-01

    Aggressive treatment of the multiply injured patient often requires early fixation of many fractures, some of which may be open. Often, patients develop postoperative fevers requiring a thorough workup to rule out infection. Recently, indium-111 white blood cell (WBC) imaging has become a valuable adjunct in the diagnosis of acute infection. The patient described had a simple, closed clavicle fracture with markedly increased activity on an indium-111 WBC scan obtained for fever workup. This subsequently proved to be a normal, healing, noninfected fracture by other diagnostic techniques. Noninfected, simple closed fractures should be added to the list of causes formore » a false-positive indium-111 WBC scan.« less

  10. False-positive iodine-131 whole-body scan findings in patients with differentiated thyroid carcinoma: report of 11 cases and review of the literature.

    PubMed

    Buton, Leckzinscka; Morel, Olivier; Gault, Patricia; Illouz, Frédéric; Rodien, Patrice; Rohmer, Vincent

    2013-07-01

    Iodine-131 (I-131) whole-body scan (WBS) plays an important role in the management of patients with differentiated thyroid carcinoma (DTC), to detect normal thyroid remnants and recurrent or metastatic disease. A focus of I-131 accumulation outside the thyroid bed and the areas of physiological uptake is strongly suggestive of a distant functioning metastasis. However, many false-positive I-131 WBS findings have been reported in the literature. We describe a series of 11 personal cases of patients with DTC, collected from 1992 to 2011, in whom diagnostic or post-treatment WBS showed false-positive retention of I-131 in various locations. False-positive accumulations of I-131 on WBS may be classified according to the underlying pathophysiological mechanisms: external and internal contaminations by body secretions, ectopic normal thyroid and gastric tissues, inflammatory and infectious diseases, benign and malignant tumors, cysts and effusions of serous cavities, thymic uptake, and other non classified causes. Clinicians must be aware of possible false-positive findings to avoid misinterpretations of the I-131 WBS, which could lead to inappropriate treatments. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  11. Developmental changes in shortening of pro-saccade reaction time while maintaining neck flexion position.

    PubMed

    Kunita, Kenji; Fujiwara, Katsuo; Kiyota, Naoe; Yaguchi, Chie; Kiyota, Takeo

    2018-01-10

    We investigated developmental changes in shortening of pro-saccade reaction time while maintaining neck flexion. Subjects comprised 135 children (3-14 years) and 29 young adults (19-23 years). Children were divided into six groups in 2-year age strata. Pro-saccade reaction tasks for 30 s were performed in neck rest and flexion positions. Reaction times under each position were averaged in every 10-s period. Under neck rest position, reaction time in the 0-10 s period was significantly longer in the 3- to 4-year-old group than in the 5- to 6-year-old group and above. No significant age effect was found for reaction time in the 0-10 s period in the 5- to 6-year-old group and above. Although a significant effect of neck flexion was not observed until the 9- to 10-year-old group, significant shortening of reaction time with neck flexion was found in the 11- to 12-year-old group and above. Furthermore, this shortening was maintained until the first 20-s period in the 11- to 12-year-old group and during the entire 30 s in the 13- to 14-year-old and above. These results suggest that brain activation with the maintenance of neck flexion, related to shortening of the pro-saccade reaction time, was found from a later age of approximately 11 years and above, compared with the age at which information-processing function in the pro-saccade was enhanced. In addition, brain activation with the maintenance of neck flexion was sustained longer with age.

  12. Factors associated with a second deferral among donors eligible for re-entry after a false-positive screening test for syphilis, HCV, HBV and HIV.

    PubMed

    Grégoire, Y; Germain, M; Delage, G

    2018-05-01

    Since 25 May 2010, all donors at our blood centre who tested false-positive for HIV, HBV, HCV or syphilis are eligible for re-entry after further testing. Donors who have a second false-positive screening test, either during qualification for or after re-entry, are deferred for life. This study reports on factors associated with the occurrence of such deferrals. Rates of second false-positive results were compared by year of deferral, transmissible disease marker, gender, age, donor status (new or repeat) and testing platform (same or different) both at qualification for re-entry and afterwards. Chi-square tests were used to compare proportions. Cox regression was used for multivariate analyses. Participation rates in the re-entry programme were 42·1%: 25·6% failed to qualify for re-entry [different platform: 2·7%; same platform: 42·9% (P < 0·0001)]. After re-entry, rates of deferral for second false-positive results were 8·4% after 3 years [different platform: 1·8%; same platform: 21·4% (P < 0·0001)]. Deferral rates were higher for HIV and HCV than for HBV at qualification when tested on the same platform. The risk, when analysed by multivariate analyses, of a second deferral for a false-positive result, both at qualification and 3 years after re-entry, was lower for donors deferred on a different platform; this risk was higher for HIV, HCV and syphilis than for HBV and for new donors if tested on the same platform. Re-entry is more often successful when donors are tested on a testing platform different from the one on which they obtained their first false-positive result. © 2018 International Society of Blood Transfusion.

  13. Positive concomitant test reactions to allergens in the standard patch test series.

    PubMed

    Landeck, Lilla; González, Ernesto; Baden, Lynn; Neumann, Konrad; Schalock, Peter

    2010-05-01

    Patch testing is performed to evaluate suspected allergic contact dermatitis. Common wisdom suggests that various allergens cross-react but only a few larger studies have published confirmations of this. The purpose of our study was to identify significant correlations between positive test reactions in a screening series. A total of 1235 patients undergoing patch testing to the Hermal standard series at the Massachusetts General Hospital, Contact Dermatitis Clinic between 1990 and 2006 were investigated. Two or more positive reactions were seen in 411 patients (33.3%). Sensitizations to eight pairs of allergens were found to have significant correlation (P reactions between formaldehyde and its releasers quaternium 15 and imidazolidinyl urea and between balsam of Peru and fragrance mix. Moreover, significant co-sensitization was identified for potassium dichromate and colophony. Three significant pairings in our study were associations between fragrances and metals. Our data confirm the previously published cross-reactions in the literature between fragrance components, and formaldehyde and formaldehyde-releasing preservatives. The increased numbers of patients with metal and fragrance sensitization can be considered as a random finding due to independent sensitization. Being aware of cross-reacting allergens is essential to success in resolving allergic dermatitis when counseling patients.

  14. Humoural immune response and pathological analysis in patients with false immune diagnosis of cystic echinococcosis

    PubMed Central

    Chen, X; Zhang, J; Feng, X; Chen, X; Yin, S; Wen, H; Zheng, S

    2014-01-01

    The patients with false immune diagnosis of hydatid disease were investigated for the humoural immune response to analyse the possible reasons and mechanism leading to false immune diagnosis. Two hundred and thirty-nine patients with nature-unknown cysts and 30 healthy controls were detected by immunological assays (four hydatid antigen-based immunogold filtration assay and enzyme-linked immune absorbent assay) and ultrasound. Sensitivity of and specificity of immunological assay and ultrasound were calculated, respectively. The serological diagnosis was compared with surgical pathology to screen the patients with false immune diagnosis for the immunoglobulin measurement and pathological analysis. The history and cyst characteristics were also reviewed. The results indicate the immunoglobulin has little influence on false immunodiagnosis. The false-negative immunodiagnosis was caused by the cysts' inactive status while the false positive caused by previous rupture, antigen cross-reaction. The clinical diagnosis of cystic echinococcosis requires a combination of immunodiagnosis and ultrasonography, which is the necessary complementary confirmation. PMID:24372157

  15. Sentinel lymph node mapping in melanoma: the issue of false-negative findings.

    PubMed

    Manca, Gianpiero; Rubello, Domenico; Romanini, Antonella; Boni, Giuseppe; Chiacchio, Serena; Tredici, Manuel; Mazzarri, Sara; Duce, Valerio; Colletti, Patrick M; Volterrani, Duccio; Mariani, Giuliano

    2014-07-01

    Management of cutaneous melanoma has changed after introduction in the clinical routine of sentinel lymph node biopsy (SLNB) for nodal staging. By defining the nodal basin status, SLNB provides a powerful prognostic information. Nevertheless, some debate still surrounds the accuracy of this procedure in terms of false-negative rate. Several large-scale studies have reported a relatively high false-negative rate (5.6%-21%), correctly defined as the proportion of false-negative results with respect to the total number of "actual" positive lymph nodes. In this review, we identified all the technical aspects that the nuclear medicine physician, the surgeon, and the pathologist should take into account to improve accuracy of the procedure and minimize the false-negative rate. In particular, SPECT/CT imaging detects more SLNs than those found by planar lymphoscintigraphy. Furthermore, the nuclear medicine community should reach a consensus on the radioactive counting rate threshold to better guide the surgeon in identifying the lymph nodes with the highest likelihood of housing metastases ("true biologic SLNs"). Analysis of the harvested SLNs by conventional techniques is also a further potential source for error. More accurate SLN analysis (eg, molecular analysis by reverse transcriptase-polymerase chain reaction) and more extensive SLN sampling identify more positive nodes, thus reducing the false-negative rate.The clinical factors identifying patients at higher-risk local recurrence after a negative SLNB include older age at diagnosis, deeper lesions, histological ulceration, and head-neck anatomic location of the primary lesion.The clinical impact of a false-negative SLNB on the prognosis of melanoma patients remains controversial, because the majority of studies have failed to demonstrate overall statistically significant disadvantage in melanoma-specific survival for false-negative SLNB patients compared with true-positive SLNB patients.When new more effective

  16. Multi-scale textural feature extraction and particle swarm optimization based model selection for false positive reduction in mammography.

    PubMed

    Zyout, Imad; Czajkowska, Joanna; Grzegorzek, Marcin

    2015-12-01

    The high number of false positives and the resulting number of avoidable breast biopsies are the major problems faced by current mammography Computer Aided Detection (CAD) systems. False positive reduction is not only a requirement for mass but also for calcification CAD systems which are currently deployed for clinical use. This paper tackles two problems related to reducing the number of false positives in the detection of all lesions and masses, respectively. Firstly, textural patterns of breast tissue have been analyzed using several multi-scale textural descriptors based on wavelet and gray level co-occurrence matrix. The second problem addressed in this paper is the parameter selection and performance optimization. For this, we adopt a model selection procedure based on Particle Swarm Optimization (PSO) for selecting the most discriminative textural features and for strengthening the generalization capacity of the supervised learning stage based on a Support Vector Machine (SVM) classifier. For evaluating the proposed methods, two sets of suspicious mammogram regions have been used. The first one, obtained from Digital Database for Screening Mammography (DDSM), contains 1494 regions (1000 normal and 494 abnormal samples). The second set of suspicious regions was obtained from database of Mammographic Image Analysis Society (mini-MIAS) and contains 315 (207 normal and 108 abnormal) samples. Results from both datasets demonstrate the efficiency of using PSO based model selection for optimizing both classifier hyper-parameters and parameters, respectively. Furthermore, the obtained results indicate the promising performance of the proposed textural features and more specifically, those based on co-occurrence matrix of wavelet image representation technique. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. College football, elections, and false-positive results in observational research

    PubMed Central

    Fowler, Anthony; Montagnes, B. Pablo

    2015-01-01

    A recent, widely cited study [Healy AJ, Malhotra N, Mo CH (2010) Proc Natl Acad Sci USA 107(29):12804–12809] finds that college football games influence voting behavior. Victories within 2 weeks of an election reportedly increase the success of the incumbent party in presidential, senatorial, and gubernatorial elections in the home county of the team. We reassess the evidence and conclude that there is likely no such effect, despite the fact that Healy et al. followed the best practices in social science and used a credible research design. Multiple independent sources of evidence suggest that the original finding was spurious—reflecting bad luck for researchers rather than a shortcoming of American voters. We fail to estimate the same effect when we leverage situations where multiple elections with differing incumbent parties occur in the same county and year. We also find that the purported effect of college football games is stronger in counties where people are less interested in college football, just as strong when the incumbent candidate does not run for reelection, and just as strong in other parts of the state outside the home county of the team. Lastly, we detect no effect of National Football League games on elections, despite their greater popularity. We conclude with recommendations for evaluating surprising research findings and avoiding similar false-positive results. PMID:26504202

  18. College football, elections, and false-positive results in observational research.

    PubMed

    Fowler, Anthony; Montagnes, B Pablo

    2015-11-10

    A recent, widely cited study [Healy AJ, Malhotra N, Mo CH (2010) Proc Natl Acad Sci USA 107(29):12804-12809] finds that college football games influence voting behavior. Victories within 2 weeks of an election reportedly increase the success of the incumbent party in presidential, senatorial, and gubernatorial elections in the home county of the team. We reassess the evidence and conclude that there is likely no such effect, despite the fact that Healy et al. followed the best practices in social science and used a credible research design. Multiple independent sources of evidence suggest that the original finding was spurious-reflecting bad luck for researchers rather than a shortcoming of American voters. We fail to estimate the same effect when we leverage situations where multiple elections with differing incumbent parties occur in the same county and year. We also find that the purported effect of college football games is stronger in counties where people are less interested in college football, just as strong when the incumbent candidate does not run for reelection, and just as strong in other parts of the state outside the home county of the team. Lastly, we detect no effect of National Football League games on elections, despite their greater popularity. We conclude with recommendations for evaluating surprising research findings and avoiding similar false-positive results.

  19. Parent Experience With False-Positive Newborn Screening Results for Cystic Fibrosis.

    PubMed

    Hayeems, Robin Z; Miller, Fiona A; Barg, Carolyn J; Bombard, Yvonne; Kerr, Elizabeth; Tam, Karen; Carroll, June C; Potter, Beth K; Chakraborty, Pranesh; Davies, Christine; Milburn, Jennifer; Patton, Sarah; Bytautas, Jessica P; Taylor, Louise; Price, April; Gonska, Tanja; Keenan, Katherine; Ratjen, Felix; Guttmann, Astrid

    2016-09-01

    The risk of psychosocial harm in families of infants with false-positive (FP) newborn bloodspot screening (NBS) results for cystic fibrosis (CF) is a longstanding concern. Whether well designed retrieval and confirmatory testing systems can mitigate risks remains unknown. Using a mixed-methods cohort design, we obtained prospective self-report data from mothers of infants with FP CF NBS results 2 to 3 months after confirmatory testing at Ontario's largest follow-up center, and from a randomly selected control sample of mothers of screen negative infants from the same region. Mothers completed a questionnaire assessing experience and psychosocial response. A sample of mothers of FP infants completed qualitative interviews. One hundred thirty-four mothers of FP infants (response rate, 55%) and 411 controls (response rate, 47%) completed questionnaires; 54 mothers of FP infants were interviewed. Selected psychosocial response measures did not detect psychosocial distress in newborns or 1 year later (P > .05). Mothers recalled distress during notification of the positive result and in the follow-up testing period related to fear of chronic illness, but valued the screening system of care in mitigating concerns. Although immediate distress was reported among mothers of FP infants, selected psychometric tools did not detect these concerns. The NBS center from which mothers were recruited minimizes delay between notification and confirmatory testing and ensures trained professionals are communicating results and facilitating follow-up. These factors may explain the presence of minimal psychosocial burden. The screening system reflected herein may be a model for NBS programs working to minimize FP-related psychosocial harm. Copyright © 2016 by the American Academy of Pediatrics.

  20. Does disseminated nontuberculous mycobacterial disease cause false-positive Determine B-LAM lateral flow assay results? A retrospective review.

    PubMed

    Nel, Jeremy S; Lippincott, Christopher K; Berhanu, Rebecca; Spencer, David C; Sanne, Ian M; Ive, Prudence

    2017-06-02

    We retrospectively reviewed the Determine TB-LAM lateral flow assay (LF-LAM) results among HIV-infected patients with disseminated nontuberculous mycobacterial (NTM) disease. LF-LAM was positive in 19/21 patients without evidence of tuberculosis coinfection. Although tuberculosis-NTM coinfection may have been underdiagnosed, our results suggest that disseminated NTM disease may cause false-positive LF-LAM results. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

  1. THE POSSIBLE MOON OF KEPLER-90g IS A FALSE POSITIVE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kipping, D. M.; Torres, G.; Buchhave, L. A.

    2015-01-20

    The discovery of an exomoon would provide deep insights into planet formation and the habitability of planetary systems, with transiting examples being particularly sought after. Of the hundreds of Kepler planets now discovered, the seven-planet system Kepler-90 is unusual for exhibiting an unidentified transit-like signal in close proximity to one of the transits of the long-period gas-giant Kepler-90g, as noted by Cabrera et al. As part of the ''Hunt for Exomoons with Kepler'' project, we investigate this possible exomoon signal and find it passes all conventional photometric, dynamical, and centroid diagnostic tests. However, pixel-level light curves indicate that the moon-like signalmore » occurs on nearly all of the target's pixels, which we confirm using a novel way of examining pixel-level data which we dub the ''transit centroid''. This test reveals that the possible exomoon to Kepler-90g is likely a false positive, perhaps due to a cosmic ray induced sudden pixel sensitivity dropout. This work highlights the extreme care required for seeking non-periodic low-amplitude transit signals, such as exomoons.« less

  2. False positive or negative results of shear-wave elastography in differentiating benign from malignant breast masses: analysis of clinical and ultrasonographic characteristics.

    PubMed

    Kim, Mi Young; Choi, Nami; Yang, Jung-Hyun; Yoo, Young Bum; Park, Kyoung Sik

    2015-10-01

    Shear-wave elastography (SWE) has the potential to improve diagnostic performance of conventional ultrasound (US) in differentiating benign from malignant breast masses. To investigate false positive or negative results of SWE in differentiating benign from malignant breast masses and to analyze clinical and imaging characteristics of the masses with false SWE findings. From May to October 2013, 166 breast lesions of 164 consecutive women (mean age, 45.3 ± 10.1 years) who had been scheduled for biopsy were included. Conventional US and SWE were performed in all women before biopsy. Clinical, ultrasonographic morphologic features and SWE parameters (pattern classification and standard deviation [SD]) were recorded and compared with the histopathology results. Patient and lesion factors in the "true" and "false" groups were compared. Of the 166 masses, 118 (71.1%) were benign and 48 (28.9%) were malignant. False SWE features were more frequently observed in benign masses. False positive rates of benign masses and false negative rates of malignancy were 53% and 8.2%, respectively, using SWE pattern analysis and were 22.4% and 10.3%, respectively, using SD values. A lesion boundary of the masses on US (P = 0.039) and younger patient age (P = 0.047) were significantly associated with false SWE findings. These clinical and ultrasonographic features need to be carefully evaluated in performance and interpretation of SWE examinations. © The Foundation Acta Radiologica 2014.

  3. LOW FALSE POSITIVE RATE OF KEPLER CANDIDATES ESTIMATED FROM A COMBINATION OF SPITZER AND FOLLOW-UP OBSERVATIONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Désert, Jean-Michel; Brown, Timothy M.; Charbonneau, David

    NASA’s Kepler mission has provided several thousand transiting planet candidates during the 4 yr of its nominal mission, yet only a small subset of these candidates have been confirmed as true planets. Therefore, the most fundamental question about these candidates is the fraction of bona fide planets. Estimating the rate of false positives of the overall Kepler sample is necessary to derive the planet occurrence rate. We present the results from two large observational campaigns that were conducted with the Spitzer Space Telescope during the the Kepler mission. These observations are dedicated to estimating the false positive rate (FPR) amongmore » the Kepler candidates. We select a sub-sample of 51 candidates, spanning wide ranges in stellar, orbital, and planetary parameter space, and we observe their transits with Spitzer at 4.5 μm. We use these observations to measures the candidate’s transit depths and infrared magnitudes. An authentic planet produces an achromatic transit depth (neglecting the modest effect of limb darkening). Conversely a bandpass-dependent depth alerts us to the potential presence of a blending star that could be the source of the observed eclipse: a false positive scenario. For most of the candidates (85%), the transit depths measured with Kepler are consistent with the transit depths measured with Spitzer as expected for planetary objects, while we find that the most discrepant measurements are due to the presence of unresolved stars that dilute the photometry. The Spitzer constraints on their own yield FPRs between 5% and depending on the Kepler Objects of Interest. By considering the population of the Kepler field stars, and by combining follow-up observations (imaging) when available, we find that the overall FPR of our sample is low. The measured upper limit on the FPR of our sample is 8.8% at a confidence level of 3σ. This observational result, which uses the achromatic property of planetary transit signals that is not

  4. Six consecutive false positive cases from cell-free fetal DNA testing in a single referring centre

    PubMed Central

    Dugo, Nella; Padula, Francesco; Mobili, Luisa; Brizzi, Cristiana; D’Emidio, Laura; Cignini, Pietro; Mesoraca, Alvaro; Bizzoco, Domenico; Cima, Antonella; Giorlandino, Claudio

    2014-01-01

    Introduction recent studies have proposed the introduction of cell-free fetal DNA testing (NIPT-Non Invasive Prenatal Testing) in routine clinical practice emphasizing its high sensibility and specificity. In any case, false positive and false negative findings may result from placental mosaicism, because cell-free fetal DNA originates mainly from placenta. Case we report six cases of women who underwent chorionic villus sampling (CVS) or amniocentesis to confirm the results from NIPT: two Turner syndromes, two Triple X, one Patau syndrome, one Edward syndrome. Results using classic cytogenetic analysis and, also, Array - Comparative Genomic Hybridization (Array CGH) the karyotype of all 5 fetuses was found to be normal. Conclusion results from NIPT must always be confirmed by invasive prenatal diagnosis. It is mandatory to inform the patient that the CVS and amniocentesis still represent the only form of prenatal diagnostic test available. PMID:25332757

  5. False-Positive Results after Environmental Pinworm PCR Testing due to Rhabditid Nematodes in Corncob Bedding

    PubMed Central

    Leblanc, Mathias; Berry, Kristina; Graciano, Sandy; Becker, Brandon; Reuter, Jon D

    2014-01-01

    Modern rodent colonies are housed in individually ventilated cages to protect the animals from contamination with adventitious pathogens. Standard health monitoring through soiled-bedding sentinels does not always detect infections, especially in the context of low pathogen prevalence. Recently proposed alternatives include analyzing environmental samples from the cages or rack exhaust by PCR to improve the detection of rodent pathogens but optimal sampling strategies have not yet been established for different microorganisms. Although generally very sensitive and specific, these molecular assays are not foolproof and subject to false-positive and –negative results and should always be interpreted cautiously with an overall understanding of the intrinsic controls and all the variables that may affect the results. Here, we report a limited Aspiculuris tetraptera outbreak in a mouse barrier facility that was detected by fecal PCR in sentinels and confirmed by fecal flotation and direct cecal examination of both sentinels and colony animals. The outbreak led to a widespread survey of all facilities for pinworms by using environmental PCR from ventilated rack exhaust plenums. Environmental PCR suggested an unexpected widespread contamination of all ventilated racks holding nonautoclaved cages, but results could not be confirmed in sentinel or colony animals by fecal flotation, cecal and colonic examination, or cage PCR testing. After additional investigation, the unexpected environmental PCR results were confirmed as false-positive findings due to the nonspecificity of the assay, leading to the amplification of rhabditid nematodes, which are not infectious in rodents but which contaminated the corncob bedding. PMID:25650980

  6. False-positive results after environmental pinworm PCR testing due to Rhabditid nematodes in Corncob bedding.

    PubMed

    Leblanc, Mathias; Berry, Kristina; Graciano, Sandy; Becker, Brandon; Reuter, Jon D

    2014-11-01

    Modern rodent colonies are housed in individually ventilated cages to protect the animals from contamination with adventitious pathogens. Standard health monitoring through soiled-bedding sentinels does not always detect infections, especially in the context of low pathogen prevalence. Recently proposed alternatives include analyzing environmental samples from the cages or rack exhaust by PCR to improve the detection of rodent pathogens but optimal sampling strategies have not yet been established for different microorganisms. Although generally very sensitive and specific, these molecular assays are not foolproof and subject to false-positive and -negative results and should always be interpreted cautiously with an overall understanding of the intrinsic controls and all the variables that may affect the results. Here, we report a limited Aspiculuris tetraptera outbreak in a mouse barrier facility that was detected by fecal PCR in sentinels and confirmed by fecal flotation and direct cecal examination of both sentinels and colony animals. The outbreak led to a widespread survey of all facilities for pinworms by using environmental PCR from ventilated rack exhaust plenums. Environmental PCR suggested an unexpected widespread contamination of all ventilated racks holding nonautoclaved cages, but results could not be confirmed in sentinel or colony animals by fecal flotation, cecal and colonic examination, or cage PCR testing. After additional investigation, the unexpected environmental PCR results were confirmed as false-positive findings due to the nonspecificity of the assay, leading to the amplification of rhabditid nematodes, which are not infectious in rodents but which contaminated the corncob bedding.

  7. False-negative rapid diagnostic tests for malaria and deletion of the histidine-rich repeat region of the hrp2 gene.

    PubMed

    Koita, Ousmane A; Doumbo, Ogobara K; Ouattara, Amed; Tall, Lalla K; Konaré, Aoua; Diakité, Mahamadou; Diallo, Mouctar; Sagara, Issaka; Masinde, Godfred L; Doumbo, Safiatou N; Dolo, Amagana; Tounkara, Anatole; Traoré, Issa; Krogstad, Donald J

    2012-02-01

    We identified 480 persons with positive thick smears for asexual Plasmodium falciparum parasites, of whom 454 had positive rapid diagnostic tests (RDTs) for the histidine-rich protein 2 (HRP2) product of the hrp2 gene and 26 had negative tests. Polymerase chain reaction (PCR) amplification for the histidine-rich repeat region of that gene was negative in one-half (10/22) of false-negative specimens available, consistent with spontaneous deletion. False-negative RDTs were found only in persons with asymptomatic infections, and multiplicities of infection (MOIs) were lower in persons with false-negative RDTs (both P < 0.001). These results show that parasites that fail to produce HRP2 can cause patent bloodstream infections and false-negative RDT results. The importance of these observations is likely to increase as malaria control improves, because lower MOIs are associated with false-negative RDTs and false-negative RDTs are more frequent in persons with asymptomatic infections. These findings suggest that the use of HRP2-based RDTs should be reconsidered.

  8. Avoiding false positive antigen detection by flow cytometry on blood cell derived microparticles: the importance of an appropriate negative control.

    PubMed

    Crompot, Emerence; Van Damme, Michael; Duvillier, Hugues; Pieters, Karlien; Vermeesch, Marjorie; Perez-Morga, David; Meuleman, Nathalie; Mineur, Philippe; Bron, Dominique; Lagneaux, Laurence; Stamatopoulos, Basile

    2015-01-01

    Microparticles (MPs), also called microvesicles (MVs) are plasma membrane-derived fragments with sizes ranging from 0.1 to 1μm. Characterization of these MPs is often performed by flow cytometry but there is no consensus on the appropriate negative control to use that can lead to false positive results. We analyzed MPs from platelets, B-cells, T-cells, NK-cells, monocytes, and chronic lymphocytic leukemia (CLL) B-cells. Cells were purified by positive magnetic-separation and cultured for 48h. Cells and MPs were characterized using the following monoclonal antibodies (CD19,20 for B-cells, CD3,8,5,27 for T-cells, CD16,56 for NK-cells, CD14,11c for monocytes, CD41,61 for platelets). Isolated MPs were stained with annexin-V-FITC and gated between 300nm and 900nm. The latex bead technique was then performed for easy detection of MPs. Samples were analyzed by Transmission (TEM) and Scanning Electron microscopy (SEM). Annexin-V positive events within a gate of 300-900nm were detected and defined as MPs. Our results confirmed that the characteristic antigens CD41/CD61 were found on platelet-derived-MPs validating our technique. However, for MPs derived from other cell types, we were unable to detect any antigen, although they were clearly expressed on the MP-producing cells in the contrary of several data published in the literature. Using the latex bead technique, we confirmed detection of CD41,61. However, the apparent expression of other antigens (already deemed positive in several studies) was determined to be false positive, indicated by negative controls (same labeling was used on MPs from different origins). We observed that mother cell antigens were not always detected on corresponding MPs by direct flow cytometry or latex bead cytometry. Our data highlighted that false positive results could be generated due to antibody aspecificity and that phenotypic characterization of MPs is a difficult field requiring the use of several negative controls.

  9. Avoiding False Positive Antigen Detection by Flow Cytometry on Blood Cell Derived Microparticles: The Importance of an Appropriate Negative Control

    PubMed Central

    Crompot, Emerence; Van Damme, Michael; Duvillier, Hugues; Pieters, Karlien; Vermeesch, Marjorie; Perez-Morga, David; Meuleman, Nathalie; Mineur, Philippe; Bron, Dominique; Lagneaux, Laurence; Stamatopoulos, Basile

    2015-01-01

    Background Microparticles (MPs), also called microvesicles (MVs) are plasma membrane-derived fragments with sizes ranging from 0.1 to 1μm. Characterization of these MPs is often performed by flow cytometry but there is no consensus on the appropriate negative control to use that can lead to false positive results. Materials and Methods We analyzed MPs from platelets, B-cells, T-cells, NK-cells, monocytes, and chronic lymphocytic leukemia (CLL) B-cells. Cells were purified by positive magnetic-separation and cultured for 48h. Cells and MPs were characterized using the following monoclonal antibodies (CD19,20 for B-cells, CD3,8,5,27 for T-cells, CD16,56 for NK-cells, CD14,11c for monocytes, CD41,61 for platelets). Isolated MPs were stained with annexin-V-FITC and gated between 300nm and 900nm. The latex bead technique was then performed for easy detection of MPs. Samples were analyzed by Transmission (TEM) and Scanning Electron microscopy (SEM). Results Annexin-V positive events within a gate of 300-900nm were detected and defined as MPs. Our results confirmed that the characteristic antigens CD41/CD61 were found on platelet-derived-MPs validating our technique. However, for MPs derived from other cell types, we were unable to detect any antigen, although they were clearly expressed on the MP-producing cells in the contrary of several data published in the literature. Using the latex bead technique, we confirmed detection of CD41,61. However, the apparent expression of other antigens (already deemed positive in several studies) was determined to be false positive, indicated by negative controls (same labeling was used on MPs from different origins). Conclusion We observed that mother cell antigens were not always detected on corresponding MPs by direct flow cytometry or latex bead cytometry. Our data highlighted that false positive results could be generated due to antibody aspecificity and that phenotypic characterization of MPs is a difficult field requiring the

  10. Implications of false positive serology of Toxoplasma gondii in a pre-transplant patient.

    PubMed

    Beal, Stacy; Racsa, Lori; Alatoom, Adnan

    2014-01-01

    A 21-year-old white male with cystic fibrosis. Pre-transplant workup in preparation for bilateral lung transplant. Cystic fibrosis diagnosed at age 3, onset of insulin-dependent diabetes around age 20, and multiple hospitalizations for pulmonary and gastrointestinal complications. FAMILY AND SOCIAL HISTORY: The patient lives with his father and stepmother, has a pet bearded dragon, and has multiple tattoos and piercings. His stepmother has a cat, but he does not clean the litter box. The pre-transplant workup included several tests for infectious diseases, tests of organ function, radiology studies, and markers of malignancy. The only significant finding was a positive Toxoplasma gondii (T. gondii) IgM titer (> or = 1:40) (reference values for IgM: negative; < 1:40, positive; > or = 1:40) and IgG (1:2048) (reference values for IgG: negative; < 1:16, equivocal; > or = 1:16 - < 1:256, positive; > or = 1:256). Testing was done by indirect immunofluorescence assay (IFA) in April 2012 in our hospital laboratory. The patient was treated with sulfadiazine, leucovorin, and pyrimethamine. Three months later (July), he returned for follow-up testing. Real-time polymerase chain reaction (PCR) for T. gondii DNA performed by a reference laboratory was negative. One month later (August), Toxoplasma serology was performed by enzyme-linked immunosorbent assay (ELISA) by a different reference laboratory and showed an elevated IgM of 0.95 IU/mL (reference values: negative; < 0.55 IU/mL, equivocal; > or = 0.55- < 0.65 IU/mL, positive; > or = 0.65 IU/mL) and a normal level of IgG (< 4 IU/mL). At this time, PCR was repeated and was negative. An additional month later (September), the patient's serology studies were performed at a third reference laboratory and showed an elevated IgM of 1.32 IU/mL (reference values: negative; 0.89, equivocal; 0.90 - 1.09, positive; > 1.10) and a normal IgG.

  11. Case report of a false positive result of the Xpert® MTB/RIF assay for rifampicin resistance in Mycobacterium tuberculosis complex.

    PubMed

    Claessens, Jolien; Mathys, Vanessa; Derdelinckx, Inge; Saegeman, Veroniek

    2017-06-01

    In the present case, we report a false positive result for the detection of rifampicin (RIF) resistance by the Xpert ® MTB/RIF assay, version G4.Miliary Mycobacterium tuberculosis infection (miliary TB) was suspected in a 50-year old Angolan woman. Imaging of the thorax and abdomen displayed diffuse lesions. The Xpert ® MTB/RIF assay conducted on the broncho-alveolar lavage (BAL) fluid was positive for TB and positive for RIF resistance. Confirmatory molecular tests and the phenotypic drug susceptibility determination supported the diagnosis of TB but not RIF resistance. The patient was treated successfully with a conventional therapeutic scheme. Because, the Xpert ® MTB/RIF assay allows the simultaneous detection of TB and RIF resistance, the World Health Organisation (WHO) recommends its use as initial diagnostic test, over microscopy, culture and phenotypic drug susceptibility testing. Even though specificity of the Xpert ® MTB/RIF assay version G4 is high, false positive test results remain possible and have to be considered for the interpretation of the RIF resistance detection by Xpert ® MTB/RIF assay.

  12. The effect of information about false negative and false positive rates on people's attitudes towards colorectal cancer screening using faecal occult blood testing (FOBt).

    PubMed

    Miles, Anne; Rodrigues, Vania; Sevdalis, Nick

    2013-11-01

    To examine the impact of numeric risk information about false negative (FN) and false positive (FP) rates in faecal occult blood testing (FOBt) on attitudes towards screening. 95 people aged 45-59, living in England, read 6 hypothetical vignettes presented online about the use of FOB testing to detect bowel cancer, in which information about FN and FP rates was systematically varied. Both verbal and numeric FN risk information reduced people's interest in screening compared with no FN information. Numeric FN risk information reduced people's perceptions of screening effectiveness and lowered perceived trust in the results of screening compared with both verbal FN information and no FN information. FP information did not affect attitudes towards FOB testing. There was limited evidence that FN information reduced interest and perceptions of screening effectiveness more in educated groups. Numeric FN risk information decreased people's perceptions of screening effectiveness and trust in the results of screening but did not affect people's interest in screening anymore than verbal FN risk information. Numeric FN information could be added to patient information without affecting interest in screening, although this needs to be replicated in a larger, more representative sample. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  13. The uterine blush. A potential false-positive in Meckel's scan interpretation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fink-Bennett, D.

    To determine the presence, prevalence, and clinical importance of /sup 99m/Tc pertechnetate uterine uptake, this retrospective analysis of 71 Meckel's scans was undertaken. Specifically, each study was evaluated for the presence of a focal accumulation of radiotracer cephalad to the bladder. Patients received an intravenous dose of 150 microCi/kg of /sup 99m/Tc pertechnetate. Each study consisted of 15 one minute anterior serial gamma camera images, and a 15, 30, and 60 minute anterior, right lateral and posterior scintiscan. Menstrual histories were obtained from all patients except two. No males (33/33), nor premenstrual (13/13), menopausal (4/4) or posthysterectomy (2/2) patients revealedmore » a uterine blush. Eleven of 15 patients (73%) with regular menses demonstrated a uterine blush. They were in the menstrual or secretory phases of their cycle. Four demonstrated no uterine uptake, had regular periods, but were in the proliferative phase of their cycle. Two with irregular periods, and one with no recorded menstrual history, manifested the blush. Radiotracer should be expected in the uterus during the menstrual and secretory phases of the menstrual cycle. It is a manifestation of a normal physiologic phenomenon, and must be recognized to prevent false-positive Meckel's scan interpretations.« less

  14. [False positive results or what's the probability that a significant P-value indicates a true effect?

    PubMed

    Cucherat, Michel; Laporte, Silvy

    2017-09-01

    The use of statistical test is central in the clinical trial. At the statistical level, obtaining a P<0.05 allows to claim the effectiveness of the new studied treatment. However, given its underlying mathematical logic the concept of "P value" is often misinterpreted. It is often assimilated, mistakenly, to the likelihood that treatment is ineffective. Actually the "P value" gives an indirect information about the plausibility of the existence of treatment effect. With "P<0.05", the probability that the treatment is effective may vary depending on other statistical parameters which are the alpha level of risk, the power of the study and especially the a priori probability of the existence of treatment effect. A "P<0.05" does not always produce the same degree of certainty. Thus there exist situations where the risk of a result "P<0.05" is in reality a false positive is very high. This is the case if the power is low, if there is an inflation of the alpha risk or if the result is exploratory or chance discoveries. This possibility is important to take into consideration when interpreting the results of clinical trials in order to avoid pushing ahead significant results in appearance, but which are likely to be actually false positive results. Copyright © 2017 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.

  15. Quantification of false positive reduction in nucleic acid purification on hemorrhagic fever DNA.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    James, Conrad D.; Pohl, Kenneth Roy; Derzon, Mark Steven

    2006-11-01

    Columbia University has developed a sensitive highly multiplexed system for genetic identification of nucleic acid targets. The primary obstacle to implementing this technology is the high rate of false positives due to high levels of unbound reporters that remain within the system after hybridization. The ability to distinguish between free reporters and reporters bound to targets limits the use of this technology. We previously demonstrated a new electrokinetic method for binary separation of kb pair long DNA molecules and oligonucleotides. The purpose of this project 99864 is to take these previous demonstrations and further develop the technique and hardware formore » field use. Specifically, our objective was to implement separation in a heterogeneous sample (containing target DNA and background oligo), to perform the separation in a flow-based device, and to develop all of the components necessary for field testing a breadboard prototype system.« less

  16. Heterotypic antibodies in Liberian sera causing anomalous reactions when using a commercial haemagglutination test for hepatitis-B surface antigen.

    PubMed

    Willcox, M C

    1976-04-01

    Agglutinins reacting with normal and tanned sheep erythrocytes were the probable cause of false positive reactions given by 51 of 214 Liberian sera when using a commercial passive-haemagglutination test for hepatitis-B surface antigen. Absorption showed these agglutinins to be identical to those described earlier in Nigerian sera. Rheumatoid factor and anti-sheep-serum antibodies although present in 12 and five per cent respectively of all sera were not responsible for any false positive reactions. The practical conclusion is that such tests, based on sheep erythrocytes are unsuitable for screening this population.

  17. An assessment of false positive rates for malaria rapid diagnostic tests caused by non-Plasmodium infectious agents and immunological factors.

    PubMed

    Gatton, Michelle L; Ciketic, Sadmir; Barnwell, John W; Cheng, Qin; Chiodini, Peter L; Incardona, Sandra; Bell, David; Cunningham, Jane; González, Iveth J

    2018-01-01

    Malaria rapid diagnostic tests (RDTs) can produce false positive (FP) results in patients with human African trypanosomiasis and rheumatoid factor (RF), but specificity against other infectious agents and immunological factors is largely unknown. Low diagnostic specificity caused by cross-reactivity may lead to over-estimates of the number of malaria cases and over-use of antimalarial drugs, at the cost of not diagnosing and treating the true underlying condition. Data from the WHO Malaria RDT Product Testing Programme was analysed to assess FP rates of 221 RDTs against four infectious agents (Chagas, dengue, Leishmaniasis and Schistosomiasis) and four immunological factors (anti-nuclear antibody, human anti-mouse antibody (HAMA), RF and rapid plasma regain). Only RDTs with a FP rate against clean negative samples less than 10% were included. Paired t-tests were used to compare product-specific FP rates on clean negative samples and samples containing non-Plasmodium infectious agents and immunological factors. Forty (18%) RDTs showed no FP results against any tested infectious agent or immunological factor. In the remaining RDTs significant and clinically relevant increases in FP rates were observed for samples containing HAMA and RF (P<0.001). There were significant correlations between product-matched FP rates for RF and HAMA on all RDT test bands (P<0.001), and FP rates for each infectious agent and immunological factor were also correlated between test bands of combination RDTs (P≤0.002). False positive results against non-Plasmodium infectious agents and immunological factors does not appear to be a universal property of malaria RDTs. However, since many malaria RDTs have elevated FP rates against HAMA and RF positive samples practitioners may need to consider the possibility of false positive results for malaria in patients with conditions that stimulate HAMA or RF.

  18. Comparative analyses across cattle genders and breeds reveal the pitfalls caused by false positive and lineage-differential copy number variations.

    PubMed

    Zhou, Yang; Utsunomiya, Yuri T; Xu, Lingyang; Hay, El Hamidi Abdel; Bickhart, Derek M; Sonstegard, Tad S; Van Tassell, Curtis P; Garcia, Jose Fernando; Liu, George E

    2016-07-06

    We compared CNV region (CNVR) results derived from 1,682 Nellore cattle with equivalent results derived from our previous analysis of Bovine HapMap samples. By comparing CNV segment frequencies between different genders and groups, we identified 9 frequent, false positive CNVRs with a total length of 0.8 Mbp that were likely caused by assembly errors. Although there was a paucity of lineage specific events, we did find one 54 kb deletion on chr5 significantly enriched in Nellore cattle. A few highly frequent CNVRs present in both datasets were detected within genomic regions containing olfactory receptor, ATP-binding cassette, and major histocompatibility complex genes. We further evaluated their impacts on downstream bioinformatics and CNV association analyses. Our results revealed pitfalls caused by false positive and lineage-differential copy number variations and will increase the accuracy of future CNV studies in both taurine and indicine cattle.

  19. False-Positive Gen-Probe Direct Mycobacterium tuberculosis Amplification Test Results for Patients with Pulmonary M. kansasii and M. avium Infections

    PubMed Central

    Jorgensen, James H.; Salinas, Jesse R.; Paxson, Rosemary; Magnon, Karen; Patterson, Jan E.; Patterson, Thomas F.

    1999-01-01

    The Gen-Probe Amplified Mycobacterium Tuberculosis Direct (MTD) test has been approved for use in the United States for the rapid diagnosis of pulmonary tuberculosis in patients with acid-fast smear-positive sputum samples since 1996. Four patients infected with human immunodeficiency virus and one chronic pulmonary-disease patient seen in our institutions with abnormal chest radiographs and fluorochrome stain-positive sputa were evaluated for tuberculosis, including performance of the MTD test on expectorated sputum samples. Three of these five patients’ sputa were highly smear-positive (i.e., more than 100 bacilli per high-power field), while two patient’s sputa contained 1 to 10 bacilli per field. MTD results on sputum specimens from these patients ranged from 43,498 to 193,858 relative light units (RLU). Gen-Probe has defined values of at least 30,000 RLU as indicative of a positive test, i.e., the presence of Mycobacterium tuberculosis RNA. Four of the patients’ sputum cultures yielded growth of M. kansasii within 6 to 12 days, and the fifth produced growth of M. avium only. One patient’s culture contained both M. kansasii and M. avium, but none of the initial or follow-up cultures from these five patients revealed M. tuberculosis. However, subsequent cultures from three of the patients again revealed M. kansasii. During the period of this study, in which MTD tests were performed on smear-positive sputum specimens from 82 patients, four of seven patients with culture-proven M. kansasii pulmonary infections yielded one or more false-positive MTD tests. The MTD sensitivity observed in this study was 93.8%, and the specificity was 85.3%. Five cultures of M. kansasii (including three of these patients’ isolates and M. kansasii ATCC 12478), and cultures of several other species were examined at densities of 105 to 107 viable CFU/ml by the MTD test. All five isolates of M. kansasii and three of three isolates of M. simiae yielded false-positive test

  20. Working memory affects false memory production for emotional events.

    PubMed

    Mirandola, Chiara; Toffalini, Enrico; Ciriello, Alfonso; Cornoldi, Cesare

    2017-01-01

    Whereas a link between working memory (WM) and memory distortions has been demonstrated, its influence on emotional false memories is unclear. In two experiments, a verbal WM task and a false memory paradigm for negative, positive or neutral events were employed. In Experiment 1, we investigated individual differences in verbal WM and found that the interaction between valence and WM predicted false recognition, with negative and positive material protecting high WM individuals against false remembering; the beneficial effect of negative material disappeared in low WM participants. In Experiment 2, we lowered the WM capacity of half of the participants with a double task request, which led to an overall increase in false memories; furthermore, consistent with Experiment 1, the increase in negative false memories was larger than that of neutral or positive ones. It is concluded that WM plays a critical role in determining false memory production, specifically influencing the processing of negative material.

  1. Prime time news: the influence of primed positive and negative emotion on susceptibility to false memories.

    PubMed

    Porter, Stephen; ten Brinke, Leanne; Riley, Sean N; Baker, Alysha

    2014-01-01

    We examined the relation between emotion and susceptibility to misinformation using a novel paradigm, the ambiguous stimuli affective priming (ASAP) paradigm. Participants (N = 88) viewed ambiguous neutral images primed either at encoding or retrieval to be interpreted as either highly positive or negative (or neutral/not primed). After viewing the images, they either were asked misleading or non-leading questions. Following a delay, memory accuracy for the original images was assessed. Results indicated that any emotional priming at encoding led to a higher susceptibility to misinformation relative to priming at recall. In particular, inducing a negative interpretation of the image at encoding led to an increased susceptibility of false memories for major misinformation (an entire object not actually present in the scene). In contrast, this pattern was reversed when priming was used at recall; a negative reinterpretation of the image decreased memory distortion relative to unprimed images. These findings suggest that, with precise experimental control, the experience of emotion at event encoding, in particular, is implicated in false memory susceptibility.

  2. A cluster of culture positive gonococcal infections but with false negative cppB gene based PCR.

    PubMed

    Lum, G; Freeman, K; Nguyen, N L; Limnios, E A; Tabrizi, S N; Carter, I; Chambers, I W; Whiley, D M; Sloots, T P; Garland, S M; Tapsall, J W

    2005-10-01

    To describe the prevalence and characteristics of isolates of Neisseria gonorrhoeae grown from urine samples that produced negative results with nucleic acid amplification assays (NAA) targeting the cppB gene. An initial cluster of culture positive, but cppB gene based NAA negative, gonococcal infections was recognised. Urine samples and suspensions of gonococci isolated over 9 months in the Northern Territory of Australia were examined using cppB gene based and other non-cppB gene based NAA. The gonococcal isolates were phenotyped by determining the auxotype/serovar (A/S) class and genotyped by pulsed field gel electrophoresis (PFGE). 14 (9.8%) of 143 gonococci isolated were of A/S class Pro(-/)Brpyut, indistinguishable on PFGE and negative in cppB gene based, but not other, NAA. This cluster represents a temporal and geographic expansion of a gonococcal subtype lacking the cppB gene with consequent loss of sensitivity of NAA dependent on amplification of this target. Gonococci lacking the cppB gene have in the past been more commonly associated with the PAU-/PCU- auxotype, a gonococcal subtype hitherto infrequently encountered in Australia. NAA based on the cppB gene as a target may produce false positive as well as false negative NAA. This suggests that unless there is continuing comparison with culture to show their utility, cppB gene based NAA should be regarded as suboptimal for use either as a diagnostic or supplemental assay for diagnosis of gonorrhoea, and NAA with alternative amplification targets should be substituted.

  3. The semantics of emotion in false memory.

    PubMed

    Brainerd, C J; Bookbinder, S H

    2018-03-26

    The emotional valence of target information has been a centerpiece of recent false memory research, but in most experiments, it has been confounded with emotional arousal. We sought to clarify the results of such research by identifying a shared mathematical relation between valence and arousal ratings in commonly administered normed materials. That relation was then used to (a) decide whether arousal as well as valence influences false memory when they are confounded and to (b) determine whether semantic properties that are known to affect false memory covary with valence and arousal ratings. In Study 1, we identified a quadratic relation between valence and arousal ratings of words and pictures that has 2 key properties: Arousal increases more rapidly as function of negative valence than positive valence, and hence, a given level of negative valence is more arousing than the same level of positive valence. This quadratic function predicts that if arousal as well as valence affects false memory when they are confounded, false memory data must have certain fine-grained properties. In Study 2, those properties were absent from norming data for the Cornell-Cortland Emotional Word Lists, indicating that valence but not arousal affects false memory in those norms. In Study 3, we tested fuzzy-trace theory's explanation of that pattern: that valence ratings are positively related to semantic properties that are known to increase false memory, but arousal ratings are not. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  4. False Memories for Affective Information in Schizophrenia.

    PubMed

    Fairfield, Beth; Altamura, Mario; Padalino, Flavia A; Balzotti, Angela; Di Domenico, Alberto; Mammarella, Nicola

    2016-01-01

    Studies have shown a direct link between memory for emotionally salient experiences and false memories. In particular, emotionally arousing material of negative and positive valence enhanced reality monitoring compared to neutral material since emotional stimuli can be encoded with more contextual details and thereby facilitate the distinction between presented and imagined stimuli. Individuals with schizophrenia appear to be impaired in both reality monitoring and memory for emotional experiences. However, the relationship between the emotionality of the to-be-remembered material and false memory occurrence has not yet been studied. In this study, 24 patients and 24 healthy adults completed a false memory task with everyday episodes composed of 12 photographs that depicted positive, negative, or neutral outcomes. Results showed how patients with schizophrenia made a higher number of false memories than normal controls ( p  < 0.05) when remembering episodes with positive or negative outcomes. The effect of valence was apparent in the patient group. For example, it did not affect the production causal false memories ( p  > 0.05) resulting from erroneous inferences but did interact with plausible, script consistent errors in patients (i.e., neutral episodes yielded a higher degree of errors than positive and negative episodes). Affective information reduces the probability of generating causal errors in healthy adults but not in patients suggesting that emotional memory impairments may contribute to deficits in reality monitoring in schizophrenia when affective information is involved.

  5. False Memories for Affective Information in Schizophrenia

    PubMed Central

    Fairfield, Beth; Altamura, Mario; Padalino, Flavia A.; Balzotti, Angela; Di Domenico, Alberto; Mammarella, Nicola

    2016-01-01

    Studies have shown a direct link between memory for emotionally salient experiences and false memories. In particular, emotionally arousing material of negative and positive valence enhanced reality monitoring compared to neutral material since emotional stimuli can be encoded with more contextual details and thereby facilitate the distinction between presented and imagined stimuli. Individuals with schizophrenia appear to be impaired in both reality monitoring and memory for emotional experiences. However, the relationship between the emotionality of the to-be-remembered material and false memory occurrence has not yet been studied. In this study, 24 patients and 24 healthy adults completed a false memory task with everyday episodes composed of 12 photographs that depicted positive, negative, or neutral outcomes. Results showed how patients with schizophrenia made a higher number of false memories than normal controls (p < 0.05) when remembering episodes with positive or negative outcomes. The effect of valence was apparent in the patient group. For example, it did not affect the production causal false memories (p > 0.05) resulting from erroneous inferences but did interact with plausible, script consistent errors in patients (i.e., neutral episodes yielded a higher degree of errors than positive and negative episodes). Affective information reduces the probability of generating causal errors in healthy adults but not in patients suggesting that emotional memory impairments may contribute to deficits in reality monitoring in schizophrenia when affective information is involved. PMID:27965600

  6. Serum Free Light Chain Assay and κ/λ Ratio Performance in Patients Without Monoclonal Gammopathies:  High False-Positive Rate.

    PubMed

    Singh, Gurmukh

    2016-08-01

    Serum free light chain assay is a recommended screening test for monoclonal gammopathies. Anecdotal observations indicated a high rate of false-positive abnormal κ/λ ratios. This study was undertaken to ascertain the magnitude of the false-positive rate and factors contributing to the error rate. Results of serum protein electrophoresis, serum free light chains, and related tests, usually done for investigation of suspected monoclonal gammopathy, were reviewed retrospectively for 270 patients and 297 observations. Using the conventional κ/λ ratio, 36.4% of the ratios were abnormal, in the absence of monoclonal gammopathy. When the renal κ/λ ratio was used, the rate of abnormal κ/λ ratios was 30.1%. In patients with a γ-globulin concentration of 1.6 g/dL or more, the usual κ/λ ratio was abnormal in 54.8% of the patients. Urine protein electrophoresis was used in 53 (19.6%) instances, whereas bone marrow examination was done in 65 (24.1%) cases. Usual κ/λ ratio was abnormal in 36.4% of the observations in patients without evidence of monoclonal gammopathy, and an abnormal κ/λ ratio should not be used as the sole indicator for diagnosis of neoplastic proliferation of the lympho-plasmacytic system. Hypergammaglobulinemia is associated with a higher rate of false-positive abnormal κ/λ ratios. Examination of urine for monoclonal immunoglobulins may be underused, and recommendations by some to use serum free light chain assay in place of, rather than as an adjunct to, urine electrophoresis are not warranted. © American Society for Clinical Pathology, 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. False Positive Positron Emission Tomography / Computed Tomography Scans in Treated Head and Neck Cancers

    PubMed Central

    Cheung, Michael K; Ong, Shawn Y; Goyal, Uma; Wertheim, Betsy C; Hsu, Charles C

    2017-01-01

    Objective Positron emission tomography/computed tomography (PET/CT) imaging for head and neck cancers (HNC) is commonly utilized for post-treatment assessment. Though PET/CT in this setting has been reported to have high negative predictive values (> 90%), positive predictive values have been reported at approximately 50%, leading to high rates of false positivity (FP) and troubling management decisions for both patient and practitioner. The objective of this study was to identify patient, disease, treatment and imaging factors that might be associated with a higher likelihood of FP on initial post-treatment PET/CT imaging for patients treated for HNC.  Materials and methods A retrospective chart review was performed on 84 patients treated for HNC who received radiation therapy (RT) as part of their overall management from October 2005 to August 2013. Of the patients screened, 19 were found to have mucosally based squamous cell carcinoma (SCC) with positive initial post-treatment PET/CT studies (23%). Fisher’s exact test was used to analyze the association between categorical variables and FP, including patient's gender, disease laterality, primary tumor site and stage, nodal and overall stage, high dose RT fraction size, number of RT fractions completed, total RT dose, biologically effective dose and timing of PET/CT acquisition. Wilcoxon rank-sum test was used to analyze the association between continuous variables and FP, including patient age, total elapsed days of RT, an amount of infused fluorodeoxyglucose 18F-FDG, pre-PET/CT serum glucose levels, and maximum standardized uptake value SUVmax. Statistically significant findings were those that were deemed p <0.05. Results Among patients with positive initial post-treatment PET/CT scans for treated HNC, there was a lower proportion of higher primary disease stage associated with FP versus true positivity (T-stage 3-4: 20 vs 78%, respectively, p=0.023). We also discovered that 50% of patients that underwent

  8. How does negative emotion cause false memories?

    PubMed

    Brainerd, C J; Stein, L M; Silveira, R A; Rohenkohl, G; Reyna, V F

    2008-09-01

    Remembering negative events can stimulate high levels of false memory, relative to remembering neutral events. In experiments in which the emotional valence of encoded materials was manipulated with their arousal levels controlled, valence produced a continuum of memory falsification. Falsification was highest for negative materials, intermediate for neutral materials, and lowest for positive materials. Conjoint-recognition analysis produced a simple process-level explanation: As one progresses from positive to neutral to negative valence, false memory increases because (a) the perceived meaning resemblance between false and true items increases and (b) subjects are less able to use verbatim memories of true items to suppress errors.

  9. Position-sensitive coincidence detection of nuclear reaction products at the Prague Van-de-Graaff accelerator

    NASA Astrophysics Data System (ADS)

    Granja, Carlos; Kraus, Vaclav; Pugatch, Valery; Kohout, Zdenek

    2017-06-01

    In low-energy nuclear reactions of astrophysical interest or fusion studies the spatial- and time-correlated detection of two and more reaction products can be a valuable tool in studies of reaction mechanisms, resolving reaction channels and measuring angular distributions of reaction products. For this purpose we constructed a configurable array of position-sensitive detectors based on the hybrid semiconductor pixel detector Timepix. Additional analog-signal electronics provide self-trigger together with extended multi-device control and synchronized readout electronics by a customized control and coincidence unit. The instrumentation, developed and used for detection of fission fragments in spontaneous and neutron induced fission as well as in charged particle detection in neutron induced reactions, is being implemented for low-energy light-ion induced nuclear reactions. Application and demonstration of the technique with two Timepix detectors on p+p elastic scattering at the Van-de-Graaff (VdG) accelerator in Prague is given.

  10. False negative rates in Drosophila cell-based RNAi screens: a case study

    PubMed Central

    2011-01-01

    Background High-throughput screening using RNAi is a powerful gene discovery method but is often complicated by false positive and false negative results. Whereas false positive results associated with RNAi reagents has been a matter of extensive study, the issue of false negatives has received less attention. Results We performed a meta-analysis of several genome-wide, cell-based Drosophila RNAi screens, together with a more focused RNAi screen, and conclude that the rate of false negative results is at least 8%. Further, we demonstrate how knowledge of the cell transcriptome can be used to resolve ambiguous results and how the number of false negative results can be reduced by using multiple, independently-tested RNAi reagents per gene. Conclusions RNAi reagents that target the same gene do not always yield consistent results due to false positives and weak or ineffective reagents. False positive results can be partially minimized by filtering with transcriptome data. RNAi libraries with multiple reagents per gene also reduce false positive and false negative outcomes when inconsistent results are disambiguated carefully. PMID:21251254

  11. Effects of depressive disorder on false memory for emotional information.

    PubMed

    Yeh, Zai-Ting; Hua, Mau-Sun

    2009-01-01

    This study explored with a false memory paradigm whether (1) depressed patients revealed more false memories and (2) whether more negative false than positive false recognition existed in subjects with depressive disorders. Thirty-two patients suffering from a major depressive episode (DSM-IV criteria), and 30 age- and education-matched normal control subjects participated in this study. After the presentation of a list of positive, negative, and neutral association items in the learning phase, subjects were asked to give a yes/no response in the recognition phase. They were also asked to rate 81 recognition items with emotional valence scores. The results revealed more negative false memories in the clinical depression group than in the normal control group; however, we did not find more negative false memories than positive ones in patients. When compared with the normal group, a more conservative response criterion for positive items was evident in patient groups. It was also found that when compared with the normal group, the subjects in the depression group perceived the positive items as less positive. On the basis of present results, it is suggested that depressed subjects judged the emotional information with criteria different from normal individuals, and patients' emotional memory intensity is attenuated by their mood.

  12. False Belief vs. False Photographs: A Test of Theory of Mind or Working Memory?

    PubMed

    Callejas, Alicia; Shulman, Gordon L; Corbetta, Maurizio

    2011-01-01

    Theory of mind (ToM), the ability to reason about other people's thoughts and beliefs, has been traditionally studied in behavioral and neuroimaging experiments by comparing performance in "false belief" and "false photograph" (control) stories. However, some evidence suggests that these stories are not matched in difficulty, complicating the interpretation of results. Here, we more fully evaluated the relative difficulty of comprehending these stories and drawing inferences from them. Subjects read false belief and false photograph stories followed by comprehension questions that probed true ("reality" questions) or false beliefs ("representation" questions) appropriate to the stories. Stories and comprehension questions were read and answered, respectively, more slowly in the false photograph than false belief conditions, indicating their greater difficulty. Interestingly, accuracy on representation questions for false photograph stories was significantly lower than for all other conditions and correlated positively with participants' working memory span scores. These results suggest that drawing representational inferences from false photo stories is particularly difficult and places heavy demands on working memory. Extensive naturalistic practice with ToM reasoning may enable a more flexible and efficient mental representation of false belief stories, resulting in lower memory load requirements. An important implication of these results is that the differential modulation of right temporal-parietal junction (RTPJ) during ToM and "false photo" control conditions may reflect the documented negative correlation of RTPJ activity with working memory load rather than a specialized involvement in ToM processes.

  13. False negative PCR despite high levels of JC virus DNA in spinal fluid: Implications for diagnostic testing

    PubMed Central

    Landry, Marie L.; Eid, Tore; Bannykh, Serguei; Major, Eugene

    2009-01-01

    Genome amplification methods such as polymerase chain reaction (PCR) have revolutionized our ability to detect viruses in spinal fluids of patients with neurologic diseases. It is not as well appreciated among clinicians that PCR protocols, quality assurance, and technical expertise vary significantly among laboratories. In a multi-laboratory blinded study of herpes simplex virus PCR, the most widely used and best validated CSF PCR assay, low-level positives were often missed and false positives were not uncommon [Schloss L, van Loon AM, Cinque P, Cleator G, Echevarria JM, Falk KI, et al. An international external quality assessment of nucleic acid amplification of herpes simplex virus. J Clin Virol 2003;28(2):175–85]. In addition, genome variability and mutations, which are increasingly recognized for a number of different viruses, can lead to falsely low or negative results. Both clinicians and laboratories must recognize the limitations of PCR, since misleading results may have serious consequences. We present here a case of a rapidly progressive, fatal neurologic illness in a young mother, whose CSF JCV DNA PCR at a reference laboratory was falsely negative. Ultimately, brain biopsy established the diagnosis of progressive multifocal leukoencephalopathy (PML). Repeat PCR testing of the same CSF targeting a different region of the genome yielded a high positive result. PMID:18701345

  14. Are we making good use of our public resources? The false-positive rate of screening by fundus photography for diabetic macular oedema.

    PubMed

    Wong, R Lm; Tsang, C W; Wong, D Sh; McGhee, S; Lam, C H; Lian, J; Lee, J Wy; Lai, J Sm; Chong, V; Wong, I Yh

    2017-08-01

    A large proportion of patients diagnosed with diabetic maculopathy using fundus photography and hence referred to specialist clinics following the current screening guidelines adopted in Hong Kong and United Kingdom are found to be false-positive, implying that they did not have macular oedema. This study aimed to evaluate the false-positive rate of diabetic maculopathy screening using the objective optical coherence tomography scan. This was a cross-sectional observational study. Consecutive diabetic patients from the Hong Kong West Cluster Diabetic Retinopathy Screening Programme with fundus photographs graded R1M1 were recruited between October 2011 and June 2013. Spectral-domain optical coherence tomography imaging was performed. Central macular thickness of ≥300 μm and/or the presence of optical coherence tomography signs of diabetic macular oedema were used to define the presence of diabetic macular oedema. Patients with conditions other than diabetes that might affect macular thickness were excluded. The mean central macular thickness in various subgroups of R1M1 patients was calculated and the proportion of subjects with central macular thickness of ≥300 μm was used to assess the false-positive rate of this screening strategy. A total of 491 patients were recruited during the study period. Of the 352 who were eligible for analysis, 44.0%, 17.0%, and 38.9% were graded as M1 due to the presence of foveal 'haemorrhages', 'exudates', or 'haemorrhages and exudates', respectively. The mean (±standard deviation) central macular thickness was 265.1±55.4 μm. Only 13.4% (95% confidence interval, 9.8%-17.0%) of eyes had a central macular thickness of ≥300 μm, and 42.9% (95% confidence interval, 37.7%-48.1%) of eyes had at least one optical coherence tomography sign of diabetic macular oedema. For patients with retinal haemorrhages only, 9.0% (95% confidence interval, 4.5%-13.5%) had a central macular thickness of ≥300 μm; 23.2% (95% confidence interval

  15. False positive results using calcitonin as a screening method for medullary thyroid carcinoma.

    PubMed

    Batista, Rafael Loch; Toscanini, Andrea Cecilia; Brandão, Lenine Garcia; Cunha-Neto, Malebranche Berardo C

    2013-05-01

    The role of serum calcitonin as part of the evaluation of thyroid nodules has been widely discussed in literature. However there still is no consensus of measurement of calcitonin in the initial evaluation of a patient with thyroid nodule. Problems concerning cost-benefit, lab methods, false positive and low prevalence of medullary thyroid carcinoma (MTC) are factors that limit this approach. We have illustrated two cases where serum calcitonin was used in the evaluation of thyroid nodule and rates proved to be high. A stimulation test was performed, using calcium as secretagogue, and calcitonin hyper-stimulation was confirmed, but anatomopathologic examination did not evidence medullar neoplasia. Anatomopathologic diagnosis detected Hashimoto thyroiditis in one case and adenomatous goiter plus an occult papillary thyroid carcinoma in the other one. Recommendation for routine use of serum calcitonin in the initial diagnostic evaluation of a thyroid nodule, followed by a confirming stimulation test if basal serum calcitonin is showed to be high, is the most currently recommended approach, but questions concerning cost-benefit and possibility of diagnosis error make the validity of this recommendation discussible.

  16. An investigation of causes of false positive single nucleotide polymorphisms using simulated reads from a small eukaryote genome.

    PubMed

    Ribeiro, Antonio; Golicz, Agnieszka; Hackett, Christine Anne; Milne, Iain; Stephen, Gordon; Marshall, David; Flavell, Andrew J; Bayer, Micha

    2015-11-11

    Single Nucleotide Polymorphisms (SNPs) are widely used molecular markers, and their use has increased massively since the inception of Next Generation Sequencing (NGS) technologies, which allow detection of large numbers of SNPs at low cost. However, both NGS data and their analysis are error-prone, which can lead to the generation of false positive (FP) SNPs. We explored the relationship between FP SNPs and seven factors involved in mapping-based variant calling - quality of the reference sequence, read length, choice of mapper and variant caller, mapping stringency and filtering of SNPs by read mapping quality and read depth. This resulted in 576 possible factor level combinations. We used error- and variant-free simulated reads to ensure that every SNP found was indeed a false positive. The variation in the number of FP SNPs generated ranged from 0 to 36,621 for the 120 million base pairs (Mbp) genome. All of the experimental factors tested had statistically significant effects on the number of FP SNPs generated and there was a considerable amount of interaction between the different factors. Using a fragmented reference sequence led to a dramatic increase in the number of FP SNPs generated, as did relaxed read mapping and a lack of SNP filtering. The choice of reference assembler, mapper and variant caller also significantly affected the outcome. The effect of read length was more complex and suggests a possible interaction between mapping specificity and the potential for contributing more false positives as read length increases. The choice of tools and parameters involved in variant calling can have a dramatic effect on the number of FP SNPs produced, with particularly poor combinations of software and/or parameter settings yielding tens of thousands in this experiment. Between-factor interactions make simple recommendations difficult for a SNP discovery pipeline but the quality of the reference sequence is clearly of paramount importance. Our findings are

  17. A false single nucleotide polymorphism generated by gene duplication compromises meat traceability.

    PubMed

    Sanz, Arianne; Ordovás, Laura; Zaragoza, Pilar; Sanz, Albina; de Blas, Ignacio; Rodellar, Clementina

    2012-07-01

    Controlling meat traceability using SNPs is an effective method of ensuring food safety. We have analyzed several SNPs to create a panel for bovine genetic identification and traceability studies. One of these was the transversion g.329C>T (Genbank accession no. AJ496781) on the cytochrome P450 17A1 gene, which has been included in previously published panels. Using minisequencing reactions, we have tested 701 samples belonging to eight Spanish cattle breeds. Surprisingly, an excess of heterozygotes was detected, implying an extreme departure from Hardy-Weinberg equilibrium (P<0.001). By alignment analysis and sequencing, we detected that the g.329C>T SNP is a false positive polymorphism, which allows us to explain the inflated heterozygotic value. We recommend that this ambiguous SNP, as well as other polymorphisms located in this region, should not be used in identification, traceability or disease association studies. Annotation of these false SNPs should improve association studies and avoid misinterpretations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Breast cancer risk is increased in the years following false-positive breast cancer screening.

    PubMed

    Goossens, Mathijs C; De Brabander, Isabel; De Greve, Jacques; Vaes, Evelien; Van Ongeval, Chantal; Van Herck, Koen; Kellen, Eliane

    2017-09-01

    A small number of studies have investigated breast cancer (BC) risk among women with a history of false-positive recall (FPR) in BC screening, but none of them has used time-to-event analysis while at the same time quantifying the effect of false-negative diagnostic assessment (FNDA). FNDA occurs when screening detects BC, but this BC is missed on diagnostic assessment (DA). As a result of FNDA, screenings that detected cancer are incorrectly classified as FPR. Our study linked data recorded in the Flemish BC screening program (women aged 50-69 years) to data from the national cancer registry. We used Cox proportional hazards models on a retrospective cohort of 298 738 women to assess the association between FPR and subsequent BC, while adjusting for potential confounders. The mean follow-up was 6.9 years. Compared with women without recall, women with a history of FPR were at an increased risk of developing BC [hazard ratio=2.10 (95% confidence interval: 1.92-2.31)]. However, 22% of BC after FPR was due to FNDA. The hazard ratio dropped to 1.69 (95% confidence interval: 1.52-1.87) when FNDA was excluded. Women with FPR have a subsequently increased BC risk compared with women without recall. The risk is higher for women who have a FPR BI-RADS 4 or 5 compared with FPR BI-RADS 3. There is room for improvement of diagnostic assessment: 41% of the excess risk is explained by FNDA after baseline screening.

  19. False positives in Biolog EcoPlates™ and MT2 MicroPlates™ caused by calcium.

    PubMed

    Pierce, Melissa L; Ward, J Evan; Dobbs, Fred C

    2014-02-01

    Biolog MicroPlates(TM) (e.g. EcoPlate(TM), MT2 MicroPlate(TM), GN MicroPlate(TM)) are useful tools for characterizing microbial communities, providing community-level physiological profiles to terrestrial and aquatic ecologists. The more recently designed Biolog EcoPlates have been used frequently in aquatic ecology with success. This study, however, reveals one major problem when using EcoPlates to evaluate samples within an estuarine or seawater matrix. At concentrations greater than 100 parts per million, the cation calcium begins to interfere with the microplate chemistry, causing false positive readings. Experiments, in which multiple treatments of natural and artificial seawater were tested, as well as calcium-addition experiments, demonstrate that calcium inhibits complete dissolution of the minimal growth medium in wells. Future studies involving Biolog EcoPlates and MicroPlates should take this effect into account, and the dilution of samples is strongly recommended to diminish the "calcium effect." Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Integrated polymerase chain reaction/electrophoresis instrument

    DOEpatents

    Andresen, Brian D.

    2000-01-01

    A new approach and instrument for field identification of micro-organisms and DNA fragments using a small and disposable device containing integrated polymerase chain reaction (PCR) enzymatic reaction wells, attached capillary electrophoresis (CE) channels, detectors, and read-out all on/in a small hand-held package. The analysis instrument may be made inexpensively, for example, of plastic, and thus is disposable, which minimizes cross contamination and the potential for false positive identification between samples. In addition, it is designed for multiple users with individual applications. The integrated PCR/CE is manufactured by the PCR well and CE channels are "stamped" into plastic depressions where conductive coatings are made in the wells and ends of the CE microchannels to carry voltage and current to heat the PCR reaction mixtures and simultaneously draw DNA bands up the CE channels. Light is transmitted through the instrument at appropriate points and detects PCR bands and identifies DNA fragments by size (retention time) and quantifies each by the amount of light generated as each phototransistor positioned below each CE channel detects a passing band. The instrument is so compact that at least 100 PCR/CE reactions/analyses can be performed easily on one detection device.

  1. Jarisch-Herxheimer reaction among HIV-positive patients with early syphilis: azithromycin versus benzathine penicillin G therapy

    PubMed Central

    Tsai, Mao-Song; Yang, Chia-Jui; Lee, Nan-Yao; Hsieh, Szu-Min; Lin, Yu-Hui; Sun, Hsin-Yun; Sheng, Wang-Huei; Lee, Kuan-Yeh; Yang, Shan-Ping; Liu, Wen-Chun; Wu, Pei-Ying; Ko, Wen-Chien; Hung, Chien-Ching

    2014-01-01

    Introduction The Jarisch-Herxheimer reaction, a febrile inflammatory reaction that often occurs after the first dose of chemotherapy in spirochetal diseases, may result in deleterious effects to patients with neurosyphilis and to pregnant women. A single 2-g oral dose of azithromycin is an alternative treatment to benzathine penicillin G for early syphilis in areas with low macrolide resistance. With its potential anti-inflammatory activity, the impact of azithromycin on the incidence of the Jarisch-Herxheimer reaction in HIV-positive patients with early syphilis has rarely been investigated. Methods In HIV-positive patients with early syphilis, the Jarisch-Herxheimer reaction was prospectively investigated using the same data collection form in 119 patients who received benzathine penicillin G between 2007 and 2009 and 198 who received azithromycin between 2012 and 2013, when shortage of benzathine penicillin G occurred in Taiwan. Between 2012 and 2013, polymerase chain reaction (PCR) assay was performed to detect Treponema pallidum DNA in clinical specimens, and PCR restriction fragment length polymorphism of the 23S ribosomal RNA was performed to detect point mutations (2058G or A2059G) that are associated with macrolide resistance. Results The overall incidence of the Jarisch-Herxheimer reaction was significantly lower in patients receiving azithromycin than those receiving benzathine penicillin G (14.1% vs. 56.3%, p<0.001). The risk increased with higher rapid plasma reagin (RPR) titres (adjusted odds ratio [AOR] per 1-log2 increase, 1.21; confidence interval [CI], 1.04–1.41), but decreased with prior penicillin therapy for syphilis (AOR, 0.37; 95% CI, 0.19–0.71) and azithromycin treatment (AOR, 0.15; 95% CI, 0.08–0.29). During the study period, 310 specimens were obtained from 198 patients with syphilis for PCR assays, from whom T. pallidum was identified in 76 patients, one of whom (1.3%) was found to be infected with T. pallidum harbouring the

  2. The False Premises and False Promises of the Movement to Privatize Public Education.

    ERIC Educational Resources Information Center

    Hawley, Willis D.

    1995-01-01

    Argues that the movement to provide parents with financial incentives to send students to private schools will increase the racial, ethnic, and socioeconomic homogeneity of American schools. Six common assumptions about the positive effects of privatizing education are examined and deemed false. Probable costs of tuition vouchers for private…

  3. Emotions and false memories: valence or arousal?

    PubMed

    Corson, Yves; Verrier, Nadège

    2007-03-01

    The effects of mood on false memories have not been studied systematically until recently. Some results seem to indicate that negative mood may reduce false recall and thus suggest an influence of emotional valence on false memory. The present research tested the effects of both valence and arousal on recall and recognition and indicates that the effect is actually due to arousal. In fact, whether participants' mood is positive, negative, or neutral, false memories are significantly more frequent under conditions of high arousal than under conditions of low arousal.

  4. Experimental Null Method to Guide the Development of Technical Procedures and to Control False-Positive Discovery in Quantitative Proteomics.

    PubMed

    Shen, Xiaomeng; Hu, Qiang; Li, Jun; Wang, Jianmin; Qu, Jun

    2015-10-02

    Comprehensive and accurate evaluation of data quality and false-positive biomarker discovery is critical to direct the method development/optimization for quantitative proteomics, which nonetheless remains challenging largely due to the high complexity and unique features of proteomic data. Here we describe an experimental null (EN) method to address this need. Because the method experimentally measures the null distribution (either technical or biological replicates) using the same proteomic samples, the same procedures and the same batch as the case-vs-contol experiment, it correctly reflects the collective effects of technical variability (e.g., variation/bias in sample preparation, LC-MS analysis, and data processing) and project-specific features (e.g., characteristics of the proteome and biological variation) on the performances of quantitative analysis. To show a proof of concept, we employed the EN method to assess the quantitative accuracy and precision and the ability to quantify subtle ratio changes between groups using different experimental and data-processing approaches and in various cellular and tissue proteomes. It was found that choices of quantitative features, sample size, experimental design, data-processing strategies, and quality of chromatographic separation can profoundly affect quantitative precision and accuracy of label-free quantification. The EN method was also demonstrated as a practical tool to determine the optimal experimental parameters and rational ratio cutoff for reliable protein quantification in specific proteomic experiments, for example, to identify the necessary number of technical/biological replicates per group that affords sufficient power for discovery. Furthermore, we assessed the ability of EN method to estimate levels of false-positives in the discovery of altered proteins, using two concocted sample sets mimicking proteomic profiling using technical and biological replicates, respectively, where the true-positives

  5. Risk assessment of false-positive quantitative real-time PCR results in food, due to detection of DNA originating from dead cells.

    PubMed

    Wolffs, Petra; Norling, Börje; Rådström, Peter

    2005-03-01

    Real-time PCR technology is increasingly used for detection and quantification of pathogens in food samples. A main disadvantage of nucleic acid detection is the inability to distinguish between signals originating from viable cells and DNA released from dead cells. In order to gain knowledge concerning risks of false-positive results due to detection of DNA originating from dead cells, quantitative PCR (qPCR) was used to investigate the degradation kinetics of free DNA in four types of meat samples. Results showed that the fastest degradation rate was observed (1 log unit per 0.5 h) in chicken homogenate, whereas the slowest rate was observed in pork rinse (1 log unit per 120.5 h). Overall results indicated that degradation occurred faster in chicken samples than in pork samples and faster at higher temperatures. Based on these results, it was concluded that, especially in pork samples, there is a risk of false-positive PCR results. This was confirmed in a quantitative study on cell death and signal persistence over a period of 28 days, employing three different methods, i.e. viable counts, direct qPCR, and finally floatation, a recently developed discontinuous density centrifugation method, followed by qPCR. Results showed that direct qPCR resulted in an overestimation of up to 10 times of the amount of cells in the samples compared to viable counts, due to detection of DNA from dead cells. However, after using floatation prior to qPCR, results resembled the viable count data. This indicates that by using of floatation as a sample treatment step prior to qPCR, the risk of false-positive PCR results due to detection of dead cells, can be minimized.

  6. Cross-reactions in specific Brachyspira spp. PCR assays caused by "Brachyspira hampsonii" isolates: implications for detection.

    PubMed

    Aller-Morán, Luis M; Martínez-Lobo, F Javier; Rubio, Pedro; Carvajal, Ana

    2016-11-01

    An emerging novel spirochete in swine, provisionally designated "Brachyspira hampsonii," has been detected worldwide. It has been associated with swine dysentery and cannot be differentiated from B. hyodysenteriae, the classical etiologic agent of this disease, using standard phenotypic methods. We evaluated cross-reactions of "B. hampsonii" isolates recovered from avian species in some of the currently available species-specific polymerase chain reaction (PCR) assays for the identification of swine Brachyspira species. Ten avian "B. hampsonii" isolates recovered from wild waterfowl were used. No false-positive results were recorded with a B. pilosicoli-specific PCR based on the amplification of a fragment of the 16S rRNA gene. However, the percentage of false-positive results varied, with a range of 10-80%, in the evaluated B. hyodysenteriae-specific assays based on the amplification of the 23S rRNA, nox, and tlyA genes. Similarly, results of the B. intermedia-specific PCR assays yielded poor specificity, with up to 80% of the "B. hampsonii" isolates tested giving false-positive results. Finally, 2 "B. hampsonii" avian isolates yielded a positive result in a B. innocens- and B. murdochii-specific PCR. This result should be interpreted very cautiously as these 2 isolates could represent a recombinant genotype. © 2016 The Author(s).

  7. High false-negative rate of anti-HCV among Egyptian patients on regular hemodialysis.

    PubMed

    El-Sherif, Assem; Elbahrawy, Ashraf; Aboelfotoh, Atef; Abdelkarim, Magdy; Saied Mohammad, Abdel-Gawad; Abdallah, Abdallah Mahmoud; Mostafa, Sadek; Elmestikawy, Amr; Elwassief, Ahmed; Salah, Mohamed; Abdelbaseer, Mohamed Ali; Abdelwahab, Kouka Saadeldin

    2012-07-01

    Routine serological testing for hepatitis C virus (HCV) infection among hemodialysis (HD) patients is currently recommended. A dilemma existed on the value of serology because some investigators reported a high rate of false-negative serologic testing. In this study, we aimed to detect the false-negative rate of anti-HCV among Egyptian HD patients. Seventy-eight HD patients, negative for anti-HCV, anti-HIV, and hepatitis B surface antigen, were tested for HCV RNA by reverse transcriptase polymerase chain reaction (RT-PCR). In the next step, the viral load was quantified by real-time PCR in RT-PCR-positive patients. Risk factors for HCV infection, as well as clinical and biochemical indicators of liver disease, were compared between false-negative and true-negative anti-HCV HD patients. The frequency of false-negative anti-HCV was 17.9%. Frequency of blood transfusion, duration of HD, dialysis at multiple centers, and diabetes mellitus were not identified as risk factors for HCV infection. The frequency of false-negative results had a linear relation to the prevalence of HCV infection in the HD units. Timely identification of HCV within dialysis units is needed in order to lower the risk of HCV spread within the HD units. The high false-negative rate of anti-HCV among HD patients in our study justifies testing of a large scale of patients for precious assessment of effectiveness of nucleic acid amplification technology testing in screening HD patient. © 2012 The Authors. Hemodialysis International © 2012 International Society for Hemodialysis.

  8. False-Positive Error Rates for Reliable Digit Span and Auditory Verbal Learning Test Performance Validity Measures in Amnestic Mild Cognitive Impairment and Early Alzheimer Disease.

    PubMed

    Loring, David W; Goldstein, Felicia C; Chen, Chuqing; Drane, Daniel L; Lah, James J; Zhao, Liping; Larrabee, Glenn J

    2016-06-01

    The objective is to examine failure on three embedded performance validity tests [Reliable Digit Span (RDS), Auditory Verbal Learning Test (AVLT) logistic regression, and AVLT recognition memory] in early Alzheimer disease (AD; n = 178), amnestic mild cognitive impairment (MCI; n = 365), and cognitively intact age-matched controls (n = 206). Neuropsychological tests scores were obtained from subjects participating in the Alzheimer's Disease Neuroimaging Initiative (ADNI). RDS failure using a ≤7 RDS threshold was 60/178 (34%) for early AD, 52/365 (14%) for MCI, and 17/206 (8%) for controls. A ≤6 RDS criterion reduced this rate to 24/178 (13%) for early AD, 15/365 (4%) for MCI, and 7/206 (3%) for controls. AVLT logistic regression probability of ≥.76 yielded unacceptably high false-positive rates in both clinical groups [early AD = 149/178 (79%); MCI = 159/365 (44%)] but not cognitively intact controls (13/206, 6%). AVLT recognition criterion of ≤9/15 classified 125/178 (70%) of early AD, 155/365 (42%) of MCI, and 18/206 (9%) of control scores as invalid, which decreased to 66/178 (37%) for early AD, 46/365 (13%) for MCI, and 10/206 (5%) for controls when applying a ≤5/15 criterion. Despite high false-positive rates across individual measures and thresholds, combining RDS ≤ 6 and AVLT recognition ≤9/15 classified only 9/178 (5%) of early AD and 4/365 (1%) of MCI patients as invalid performers. Embedded validity cutoffs derived from mixed clinical groups produce unacceptably high false-positive rates in MCI and early AD. Combining embedded PVT indicators lowers the false-positive rate. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Rejecting Astrophysical False Positives from the TrES Transiting Planet Survey: The Example of GSC 03885-00829

    NASA Astrophysics Data System (ADS)

    O'Donovan, Francis T.; Charbonneau, David; Torres, Guillermo; Mandushev, Georgi; Dunham, Edward W.; Latham, David W.; Alonso, Roi; Brown, Timothy M.; Esquerdo, Gilbert A.; Everett, Mark E.; Creevey, Orlagh L.

    2006-06-01

    Ground-based wide-field surveys for nearby transiting gas giants are yielding far fewer true planets than astrophysical false positives, some of which are difficult to reject. Recent experience has highlighted the need for careful analysis to eliminate astronomical systems in which light from a faint eclipsing binary is blended with that from a bright star. During the course of the Transatlantic Exoplanet Survey, we identified a system presenting a transit-like periodic signal. We obtained the proper motion and infrared color of this target (GSC 03885-00829) from publicly available catalogs, which suggested this star is an F dwarf, supporting our transit hypothesis. This spectral classification was confirmed using spectroscopic observations from which we determined the stellar radial velocity. The star did not exhibit any signs of a stellar mass companion. However, subsequent multicolor photometry displayed a color-dependent transit depth, indicating that a blend was the likely source of the eclipse. We successfully modeled our initial photometric observations of GSC 03885-00829 as the light from a K dwarf binary system superimposed on the light from a late F dwarf star. High-dispersion spectroscopy confirmed the presence of light from a cool stellar photosphere in the spectrum of this system. With this candidate, we demonstrate both the difficulty in identifying certain types of false positives in a list of candidate transiting planets and our procedure for rejecting these imposters, which may be useful to other groups performing wide-field transit surveys. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  10. When the Single Matters more than the Group (II): Addressing the Problem of High False Positive Rates in Single Case Voxel Based Morphometry Using Non-parametric Statistics.

    PubMed

    Scarpazza, Cristina; Nichols, Thomas E; Seramondi, Donato; Maumet, Camille; Sartori, Giuseppe; Mechelli, Andrea

    2016-01-01

    In recent years, an increasing number of studies have used Voxel Based Morphometry (VBM) to compare a single patient with a psychiatric or neurological condition of interest against a group of healthy controls. However, the validity of this approach critically relies on the assumption that the single patient is drawn from a hypothetical population with a normal distribution and variance equal to that of the control group. In a previous investigation, we demonstrated that family-wise false positive error rate (i.e., the proportion of statistical comparisons yielding at least one false positive) in single case VBM are much higher than expected (Scarpazza et al., 2013). Here, we examine whether the use of non-parametric statistics, which does not rely on the assumptions of normal distribution and equal variance, would enable the investigation of single subjects with good control of false positive risk. We empirically estimated false positive rates (FPRs) in single case non-parametric VBM, by performing 400 statistical comparisons between a single disease-free individual and a group of 100 disease-free controls. The impact of smoothing (4, 8, and 12 mm) and type of pre-processing (Modulated, Unmodulated) was also examined, as these factors have been found to influence FPRs in previous investigations using parametric statistics. The 400 statistical comparisons were repeated using two independent, freely available data sets in order to maximize the generalizability of the results. We found that the family-wise error rate was 5% for increases and 3.6% for decreases in one data set; and 5.6% for increases and 6.3% for decreases in the other data set (5% nominal). Further, these results were not dependent on the level of smoothing and modulation. Therefore, the present study provides empirical evidence that single case VBM studies with non-parametric statistics are not susceptible to high false positive rates. The critical implication of this finding is that VBM can be used

  11. An Evaluation of Unit and ½ Mass Correction Approaches as a Means of Minimizing the False Positives Produced by M+2 species in US EPA Method 200.8 using ICP-MS

    EPA Science Inventory

    Rare earth elements (REE) and certain alkaline earths can produce M+2 interferences in ICP-MS because they have sufficiently low second ionization energies. Four REEs (150Sm, 150Nd, 156Gd and 156Dy) produce false positives on 75As and 78Se and 132Ba can produce a false positive ...

  12. Minimotif Miner 3.0: database expansion and significantly improved reduction of false-positive predictions from consensus sequences.

    PubMed

    Mi, Tian; Merlin, Jerlin Camilus; Deverasetty, Sandeep; Gryk, Michael R; Bill, Travis J; Brooks, Andrew W; Lee, Logan Y; Rathnayake, Viraj; Ross, Christian A; Sargeant, David P; Strong, Christy L; Watts, Paula; Rajasekaran, Sanguthevar; Schiller, Martin R

    2012-01-01

    Minimotif Miner (MnM available at http://minimotifminer.org or http://mnm.engr.uconn.edu) is an online database for identifying new minimotifs in protein queries. Minimotifs are short contiguous peptide sequences that have a known function in at least one protein. Here we report the third release of the MnM database which has now grown 60-fold to approximately 300,000 minimotifs. Since short minimotifs are by their nature not very complex we also summarize a new set of false-positive filters and linear regression scoring that vastly enhance minimotif prediction accuracy on a test data set. This online database can be used to predict new functions in proteins and causes of disease.

  13. Position-specific isotope modeling of organic micropollutants transformations through different reaction pathways

    NASA Astrophysics Data System (ADS)

    Jin, Biao; Rolle, Massimo

    2016-04-01

    Organic compounds are produced in vast quantities for industrial and agricultural use, as well as for human and animal healthcare [1]. These chemicals and their metabolites are frequently detected at trace levels in fresh water environments where they undergo degradation via different reaction pathways. Compound specific stable isotope analysis (CSIA) is a valuable tool to identify such degradation pathways in different environmental systems. Recent advances in analytical techniques have promoted the fast development and implementation of multi-element CSIA. However, quantitative frameworks to evaluate multi-element stable isotope data and incorporating mechanistic information on the degradation processes [2,3] are still lacking. In this study we propose a mechanism-based modeling approach to simultaneously evaluate concentration as well as bulk and position-specific multi-element isotope evolution during the transformation of organic micropollutants. The model explicitly simulates position-specific isotopologues for those atoms that experience isotope effects and, thereby, provides a mechanistic description of isotope fractionation occurring at different molecular positions. We validate the proposed approach with the concentration and multi-element isotope data of three selected organic micropollutants: dichlorobenzamide (BAM), isoproturon (IPU) and diclofenac (DCF). The model precisely captures the dual element isotope trends characteristic of different reaction pathways and their range of variation consistent with observed multi-element (C, N) bulk isotope fractionation. The proposed approach can also be used as a tool to explore transformation pathways in scenarios for which position-specific isotope data are not yet available. [1] Schwarzenbach, R.P., Egli, T., Hofstetter, T.B., von Gunten, U., Wehrli, B., 2010. Global Water Pollution and Human Health. Annu. Rev. Environ. Resour. doi:10.1146/annurev-environ-100809-125342. [2] Jin, B., Haderlein, S.B., Rolle, M

  14. Simultaneous Genotype Calling and Haplotype Phasing Improves Genotype Accuracy and Reduces False-Positive Associations for Genome-wide Association Studies

    PubMed Central

    Browning, Brian L.; Yu, Zhaoxia

    2009-01-01

    We present a novel method for simultaneous genotype calling and haplotype-phase inference. Our method employs the computationally efficient BEAGLE haplotype-frequency model, which can be applied to large-scale studies with millions of markers and thousands of samples. We compare genotype calls made with our method to genotype calls made with the BIRDSEED, CHIAMO, GenCall, and ILLUMINUS genotype-calling methods, using genotype data from the Illumina 550K and Affymetrix 500K arrays. We show that our method has higher genotype-call accuracy and yields fewer uncalled genotypes than competing methods. We perform single-marker analysis of data from the Wellcome Trust Case Control Consortium bipolar disorder and type 2 diabetes studies. For bipolar disorder, the genotype calls in the original study yield 25 markers with apparent false-positive association with bipolar disorder at a p < 10−7 significance level, whereas genotype calls made with our method yield no associated markers at this significance threshold. Conversely, for markers with replicated association with type 2 diabetes, there is good concordance between genotype calls used in the original study and calls made by our method. Results from single-marker and haplotypic analysis of our method's genotype calls for the bipolar disorder study indicate that our method is highly effective at eliminating genotyping artifacts that cause false-positive associations in genome-wide association studies. Our new genotype-calling methods are implemented in the BEAGLE and BEAGLECALL software packages. PMID:19931040

  15. Polymer nanoassemblies with hydrophobic pendant groups in the core induce false positive siRNA transfection in luciferase reporter assays.

    PubMed

    Rheiner, Steven; Reichel, Derek; Rychahou, Piotr; Izumi, Tadahide; Yang, Hsin-Sheng; Bae, Younsoo

    2017-08-07

    Poly(ethylene glycol)-conjugated polyethylenimine (PEG-PEI) is a widely studied cationic polymer used to develop non-viral vectors for siRNA therapy of genetic disorders including cancer. Cell lines stably expressing luciferase reporter protein typically evaluate the transfection efficacy of siRNA/PEG-PEI complexes, however recent findings revealed that PEG-PEI can reduce luciferase expression independent of siRNA. This study elucidates a cause of the false positive effect in luciferase assays by using polymer nanoassemblies (PNAs) made from PEG, PEI, poly-(l-lysine) (PLL), palmitate (PAL), and deoxycholate (DOC): PEG-PEI (2P), PEG-PEI-PAL (3P), PEG-PLL (2P'), PEG-PLL-PAL (3P'), and PEG-PEI-DOC (2PD). In vitro transfection and western blot assays of luciferase using a colorectal cancer cell line expressing luciferase (HT29/LUC) concluded that 2P and 2P' caused no luciferase expression reduction while hydrophobically modified PNAs induced a 35-50% reduction (3P'<2PD<3P). Although cell viability remained stagnant, 3P triggered cellular stress responses including increased membrane porosity and decreased ATP and cellular protein concentrations. Raman spectroscopy suggested that hydrophobic groups influence PNA conformation changes, which may have caused over-ubiquitination and degradation of luciferase in the cells. These results indicate that hydrophobically modified PEG-PEI induces cellular distress causing over-ubiquitination of the luciferase protein, producing false positive siRNA transfection in the luciferase assay. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Psychoactive drugs and false memory: comparison of dextroamphetamine and delta-9-tetrahydrocannabinol on false recognition

    PubMed Central

    Ballard, Michael E.; Gallo, David A.; de Wit, Harriet

    2014-01-01

    Rationale Several psychoactive drugs are known to influence episodic memory. However, these drugs’ effects on false memory, or the tendency to incorrectly remember nonstudied information, remain poorly understood. Objectives Here, we examined the effects of two commonly used psychoactive drugs, one with memory-enhancing properties (dextroamphetamine; AMP), and another with memory-impairing properties (Δ9-tetrahydrocannabinol; THC), on false memory using the Deese/Roediger–McDermott (DRM) illusion. Methods Two parallel studies were conducted in which healthy volunteers received either AMP (0, 10, and 20 mg) or THC (0, 7.5, and 15 mg) in within-subjects, randomized, double-blind designs. Participants studied DRM word lists under the influence of the drugs, and their recognition memory for the studied words was tested 2 days later, under sober conditions. Results As expected, AMP increased memory of studied words relative to placebo, and THC reduced memory of studied words. Although neither drug significantly affected false memory relative to placebo, AMP increased false memory relative to THC. Across participants, both drugs’ effects on true memory were positively correlated with their effects on false memory. Conclusions Our results indicate that AMP and THC have opposing effects on true memory, and these effects appear to correspond to similar, albeit more subtle, effects on false memory. These findings are consistent with previous research using the DRM illusion and provide further evidence that psychoactive drugs can affect the encoding processes that ultimately result in the creation of false memories. PMID:21647577

  17. Psychoactive drugs and false memory: comparison of dextroamphetamine and δ-9-tetrahydrocannabinol on false recognition.

    PubMed

    Ballard, Michael E; Gallo, David A; de Wit, Harriet

    2012-01-01

    Several psychoactive drugs are known to influence episodic memory. However, these drugs' effects on false memory, or the tendency to incorrectly remember nonstudied information, remain poorly understood. Here, we examined the effects of two commonly used psychoactive drugs, one with memory-enhancing properties (dextroamphetamine; AMP), and another with memory-impairing properties (Δ(9)-tetrahydrocannabinol; THC), on false memory using the Deese/Roediger-McDermott (DRM) illusion. Two parallel studies were conducted in which healthy volunteers received either AMP (0, 10, and 20 mg) or THC (0, 7.5, and 15 mg) in within-subjects, randomized, double-blind designs. Participants studied DRM word lists under the influence of the drugs, and their recognition memory for the studied words was tested 2 days later, under sober conditions. As expected, AMP increased memory of studied words relative to placebo, and THC reduced memory of studied words. Although neither drug significantly affected false memory relative to placebo, AMP increased false memory relative to THC. Across participants, both drugs' effects on true memory were positively correlated with their effects on false memory. Our results indicate that AMP and THC have opposing effects on true memory, and these effects appear to correspond to similar, albeit more subtle, effects on false memory. These findings are consistent with previous research using the DRM illusion and provide further evidence that psychoactive drugs can affect the encoding processes that ultimately result in the creation of false memories.

  18. Evaluation of HIV testing algorithms in Ethiopia: the role of the tie-breaker algorithm and weakly reacting test lines in contributing to a high rate of false positive HIV diagnoses.

    PubMed

    Shanks, Leslie; Siddiqui, M Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Pirou, Erwan; Ritmeijer, Koert; Masiga, Johnson; Abebe, Almaz

    2015-02-03

    In Ethiopia a tiebreaker algorithm using 3 rapid diagnostic tests (RDTs) in series is used to diagnose HIV. Discordant results between the first 2 RDTs are resolved by a third 'tiebreaker' RDT. Médecins Sans Frontières uses an alternate serial algorithm of 2 RDTs followed by a confirmation test for all double positive RDT results. The primary objective was to compare the performance of the tiebreaker algorithm with a serial algorithm, and to evaluate the addition of a confirmation test to both algorithms. A secondary objective looked at the positive predictive value (PPV) of weakly reactive test lines. The study was conducted in two HIV testing sites in Ethiopia. Study participants were recruited sequentially until 200 positive samples were reached. Each sample was re-tested in the laboratory on the 3 RDTs and on a simple to use confirmation test, the Orgenics Immunocomb Combfirm® (OIC). The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. 2620 subjects were included with a HIV prevalence of 7.7%. Each of the 3 RDTs had an individual specificity of at least 99%. The serial algorithm with 2 RDTs had a single false positive result (1 out of 204) to give a PPV of 99.5% (95% CI 97.3%-100%). The tiebreaker algorithm resulted in 16 false positive results (PPV 92.7%, 95% CI: 88.4%-95.8%). Adding the OIC confirmation test to either algorithm eliminated the false positives. All the false positives had at least one weakly reactive test line in the algorithm. The PPV of weakly reacting RDTs was significantly lower than those with strongly positive test lines. The risk of false positive HIV diagnosis in a tiebreaker algorithm is significant. We recommend abandoning the tie-breaker algorithm in favour of WHO recommended serial or parallel algorithms, interpreting weakly reactive test lines as indeterminate results requiring further testing except in the setting of blood transfusion, and most importantly, adding a confirmation test

  19. Affective valence influences participant's susceptibility to false memories and illusory recollection.

    PubMed

    Dehon, Hedwige; Larøi, Frank; Van der Linden, Martial

    2010-10-01

    This study examined the influence of emotional valence on the production of DRM false memories (Roediger & McDermott, 1995). Participants were presented with neutral, positive, or negative DRM lists for a later recognition (Experiment 1) or recall (Experiment 2) test. In both experiments, confidence and recollective experience (i.e., "Remember-Know" judgments; Tulving, 1985) were also assessed. Results consistently showed that, compared with neutral lists, affective lists induced more false recognition and recall of nonpresented critical lures. Moreover, although confidence ratings did not differ between the false remembering from the different kinds of lists, "Remember" responses were more often associated with negative than positive and neutral false remembering of the critical lures. In contrast, positive false remembering of the critical lures was more often associated with "Know" responses. These results are discussed in light of the Paradoxical Negative Emotion (PNE) hypothesis (Porter, Taylor, & ten Bricke, 2008). (PsycINFO Database Record (c) 2010 APA, all rights reserved).

  20. A false positive newborn screening result due to a complex allele carrying two frequent CF-causing variants.

    PubMed

    Bergougnoux, Anne; Boureau-Wirth, Amandine; Rouzier, Cécile; Altieri, Jean-Pierre; Verneau, Fanny; Larrieu, Lise; Koenig, Michel; Claustres, Mireille; Raynal, Caroline

    2016-05-01

    The detection of two frequent CFTR disease-causing variations in the context of a newborn screening program (NBS) usually leads to the diagnosis of cystic fibrosis (CF) and a relevant genetic counseling in the family. In the present study, CF-causing variants p.Phe508del (F508del) and c.3140-26A>G (3272-26A>G) were identified on a neonate with positive ImmunoReactive Trypsinogen test by the Elucigene™ CF30 kit. The CF diagnosis initially suggested, despite three inconclusive Sweat Chloride Tests (SCT), was finally ruled out after the familial segregation study combined with a negative SCT. Haplotype studies, based on the comparison of 80 p.Phe508del haplotypes, suggested a probable de novo occurrence of c.3140-26A>G on the p.Phe508del ancestral allele in this family. This false positive case emphasizes the importance of SCT in the NBS strategy. Moreover, it raises the need for familial segregation studies in CF and in overall molecular diagnosis strategy of autosomal recessive diseases. Copyright © 2016 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

  1. False Recognition in Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease-Disinhibition or Amnesia?

    PubMed

    Flanagan, Emma C; Wong, Stephanie; Dutt, Aparna; Tu, Sicong; Bertoux, Maxime; Irish, Muireann; Piguet, Olivier; Rao, Sulakshana; Hodges, John R; Ghosh, Amitabha; Hornberger, Michael

    2016-01-01

    Episodic memory recall processes in Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) can be similarly impaired, whereas recognition performance is more variable. A potential reason for this variability could be false-positive errors made on recognition trials and whether these errors are due to amnesia per se or a general over-endorsement of recognition items regardless of memory. The current study addressed this issue by analysing recognition performance on the Rey Auditory Verbal Learning Test (RAVLT) in 39 bvFTD, 77 AD and 61 control participants from two centers (India, Australia), as well as disinhibition assessed using the Hayling test. Whereas both AD and bvFTD patients were comparably impaired on delayed recall, bvFTD patients showed intact recognition performance in terms of the number of correct hits. However, both patient groups endorsed significantly more false-positives than controls, and bvFTD and AD patients scored equally poorly on a sensitivity index (correct hits-false-positives). Furthermore, measures of disinhibition were significantly associated with false positives in both groups, with a stronger relationship with false-positives in bvFTD. Voxel-based morphometry analyses revealed similar neural correlates of false positive endorsement across bvFTD and AD, with both patient groups showing involvement of prefrontal and Papez circuitry regions, such as medial temporal and thalamic regions, and a DTI analysis detected an emerging but non-significant trend between false positives and decreased fornix integrity in bvFTD only. These findings suggest that false-positive errors on recognition tests relate to similar mechanisms in bvFTD and AD, reflecting deficits in episodic memory processes and disinhibition. These findings highlight that current memory tests are not sufficient to accurately distinguish between bvFTD and AD patients.

  2. Arousal-But Not Valence-Reduces False Memories at Retrieval.

    PubMed

    Mirandola, Chiara; Toffalini, Enrico

    2016-01-01

    Mood affects both memory accuracy and memory distortions. However, some aspects of this relation are still poorly understood: (1) whether valence and arousal equally affect false memory production, and (2) whether retrieval-related processes matter; the extant literature typically shows that mood influences memory performance when it is induced before encoding, leaving unsolved whether mood induced before retrieval also impacts memory. We examined how negative, positive, and neutral mood induced before retrieval affected inferential false memories and related subjective memory experiences. A recognition-memory paradigm for photographs depicting script-like events was employed. Results showed that individuals in both negative and positive moods-similar in arousal levels-correctly recognized more target events and endorsed fewer false memories (and these errors were linked to remember responses less frequently), compared to individuals in neutral mood. This suggests that arousal (but not valence) predicted memory performance; furthermore, we found that arousal ratings provided by participants were more adequate predictors of memory performance than their actual belonging to either positive, negative or neutral mood groups. These findings suggest that arousal has a primary role in affecting memory, and that mood exerts its power on true and false memory even when induced at retrieval.

  3. Intellectual factors in false memories of patients with schizophrenia.

    PubMed

    Zhu, Bi; Chen, Chuansheng; Loftus, Elizabeth F; Dong, Qi; Lin, Chongde; Li, Jun

    2018-07-01

    The current study explored the intellectual factors in false memories of 139 patients with schizophrenia, using a recognition task and an IQ test. The full-scale IQ score of the participants ranged from 57 to 144 (M = 100, SD = 14). The full IQ score had a negative correlation with false recognition in patients with schizophrenia, and positive correlations with high-confidence true recognition and discrimination rates. Further analyses with the subtests' scores revealed that false recognition was negatively correlated with scores of performance IQ (and one of its subtests: picture arrangement), whereas true recognition was positively correlated with scores of verbal IQ (and two of its subtests: information and digit span). High-IQ patients had less false recognition (overall or high-confidence false recognition), more high-confidence true recognition, and higher discrimination abilities than those with low IQ. These findings contribute to a better understanding of the cognitive mechanism in false memory of patients with schizophrenia, and are of practical relevance to the evaluation of memory reliability in patients with different intellectual levels. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Motivated reconstruction: The effect of brand commitment on false memories.

    PubMed

    Montgomery, Nicole Votolato; Rajagopal, Priyali

    2018-06-01

    Across 5 studies, we examine the effect of prior brand commitment on the creation of false memories about product experience after reading online product reviews. We find that brand commitment and the valence of reviews to which consumers are exposed, interact to affect the incidence of false memories. Thus, highly committed consumers are more susceptible to the creation of false experience memories on exposure to positive versus negative reviews, whereas low commitment consumers exhibit similar levels of false memories in response to both positive and negative reviews. Further, these differences across brand commitment are attenuated when respondents are primed with an accuracy motivation, suggesting that the biasing effects of commitment are likely because of the motivation to defend the committed brand. Finally, we find that differences in false memories subsequently lead to differences in intentions to spread word-of-mouth (e.g., recommend the product to friends), suggesting that the consequences of false product experience memories can be significant for marketers and consumers. Our findings contribute to the literatures in false memory and marketing by documenting a motivated bias in false memories because of brand commitment. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  5. Neural Network Target Identification System for False Alarm Reduction

    NASA Technical Reports Server (NTRS)

    Ye, David; Edens, Weston; Lu, Thomas T.; Chao, Tien-Hsin

    2009-01-01

    A multi-stage automated target recognition (ATR) system has been designed to perform computer vision tasks with adequate proficiency in mimicking human vision. The system is able to detect, identify, and track targets of interest. Potential regions of interest (ROIs) are first identified by the detection stage using an Optimum Trade-off Maximum Average Correlation Height (OT-MACH) filter combined with a wavelet transform. False positives are then eliminated by the verification stage using feature extraction methods in conjunction with neural networks. Feature extraction transforms the ROIs using filtering and binning algorithms to create feature vectors. A feed forward back propagation neural network (NN) is then trained to classify each feature vector and remove false positives. This paper discusses the test of the system performance and parameter optimizations process which adapts the system to various targets and datasets. The test results show that the system was successful in substantially reducing the false positive rate when tested on a sonar image dataset.

  6. Role of dissociation in "false drug allergy".

    PubMed

    Rodriguez-Cano, Teresa; Beato-Fernandez, Luis; Galindo-Bonilla, Pedro

    2006-01-01

    The aim of the present study was to analyze the influence of dissociation on the "false allergy" phenomenon. Fifty-five individuals (11 males and 44 females) who consecutively presented for the study of their suspected drug allergy were assessed. After the challenge test, false allergy was found in 39.3% and placebo positive response in 12.5% of the patients. Seven patients (12.5%) scored above the cut-off point of 20 on the Dissociative Experiences Scale (DES), and 5 out of this group (71.4%) fit in the "false allergy" group. Pathological scores on the DES were associated with the diagnosis of "false allergy" (OR = 9.583, 95% CI = 1.002, 91.621). The effect of age, gender, and other psychopathological variables was controlled. High levels of dissociation might predispose to false drug allergy, which could complicate pharmacological treatment and therefore increase the patient's complaints and demands for medical attention.

  7. False HDAC Inhibition by Aurone Compound.

    PubMed

    Itoh, Yukihiro; Suzuki, Miki; Matsui, Taiji; Ota, Yosuke; Hui, Zi; Tsubaki, Kazunori; Suzuki, Takayoshi

    2016-01-01

    Fluorescence assays are useful tools for estimating enzymatic activity. Their simplicity and manageability make them suitable for screening enzyme inhibitors in drug discovery studies. However, researchers need to pay attention to compounds that show auto-fluorescence and quench fluorescence, because such compounds lower the accuracy of the fluorescence assay systems by producing false-positive or negative results. In this study, we found that aurone compound 7, which has been reported as a histone deacetylase (HDAC) inhibitor, gave false-positive results. Although compound 7 was identified by an in vitro HDAC fluorescence assay, it did not show HDAC inhibitory activity in a cell-based assay, leading us to suspect its in vitro HDAC inhibitory activity. As a result of verification experiments, we found that compound 7 interferes with the HDAC fluorescence assay by quenching the HDAC fluorescence signal. Our findings underscore the faults of fluorescence assays and call attention to careless interpretation.

  8. The Lifetime Economic Burden of Inaccurate HER2 Testing: Estimating the Costs of False-Positive and False-Negative HER2 Test Results in US Patients with Early-Stage Breast Cancer.

    PubMed

    Garrison, Louis P; Babigumira, Joseph B; Masaquel, Anthony; Wang, Bruce C M; Lalla, Deepa; Brammer, Melissa

    2015-06-01

    Patients with breast cancer whose tumors test positive for human epidermal growth factor receptor 2 (HER2) are treated with HER2-targeted therapies such as trastuzumab, but limitations with HER2 testing may lead to false-positive (FP) or false-negative (FN) results. To develop a US-level model to estimate the effect of tumor misclassification on health care costs and patient quality-adjusted life-years (QALYs). Decision analysis was used to estimate the number of patients with early-stage breast cancer (EBC) whose HER2 status was misclassified in 2012. FP results were assumed to generate unnecessary trastuzumab costs and unnecessary cases of trastuzumab-related cardiotoxicity. FN results were assumed to save money on trastuzumab, but with a loss of QALYs and greater risk of disease recurrence and its associated costs. QALYs were valued at $100,000 under a net monetary benefit approach. Among 226,870 women diagnosed with EBC in 2012, 3.12% (n = 7,070) and 2.18% (n = 4,955) were estimated to have had FP and FN test results, respectively. Approximately 8400 QALYs (discounted, lifetime) were lost among women not receiving trastuzumab because of FN results. The estimated incremental per-patient lifetime burden of FP or FN results was $58,900 and $116,000, respectively. The implied incremental losses to society were $417 million and $575 million, respectively. HER2 tests result in misclassification and nonoptimal treatment of approximately 12,025 US patients with EBC annually. The total economic societal loss of nearly $1 billion suggests that improvements in HER2 testing accuracy are needed and that further clinical and economic studies are warranted. Copyright © 2015 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  9. Evidence for false-positive results for boldenone testing of veal urine due to faecal cross-contamination during sampling.

    PubMed

    Sgoifo Rossi, C A; Arioli, F; Bassini, A; Chiesa, L M; Dell'Orto, V; Montana, M; Pompa, G

    2004-08-01

    European Directive 96/22/EC, which controls veterinary residues in animals, does not permit the presence of synthetic growth promoters in products of animal origin or in livestock. Boldenone is categorized in class A3 (growth promoters -- steroids) and is thus a banned substance. Testing of veal urine for banned substances is part of the European Union statutory programme for animals going into the food chain. In relation to this monitoring, three studies were conducted to investigate the apparent presence of the banned growth promoter boldenone in veal urine, which was suspected as being caused by interference from faecal contamination of the sample. In the first study, urine samples were collected at different times (time 0 and after 30 min) using (1) a conventional zoonotechnical apron and (2) a technique designed specifically to avoid faecal contamination ('kettle'). This resulted in samples that were, respectively, positive and negative for the presence of alpha-boldenone (alpha-BOL). In a second study, urine samples negative to alpha-BOL were collected from eight veal calves, but became positive after deliberate faecal contamination. In a third study, data obtained from the Italian RNP (Residual National Program) indicated that 18.1% of 3295 urine samples collected using the zootechnical apron were positive for alpha-BOL and 2.1% for beta-boldenone (beta-BOL), whilst of 902 samples collected using the kettle, beta-BOL was not detected in any samples and only 0.2% were positive to alpha-BOL, in concentrations lower than 2 ng ml(-1). These results further support the supposition that faecal contamination of the urine during sample collection can lead to false-positive results during boldenone analysis.

  10. False-Positive Rate of AKI Using Consensus Creatinine–Based Criteria

    PubMed Central

    Lin, Jennie; Fernandez, Hilda; Shashaty, Michael G.S.; Negoianu, Dan; Testani, Jeffrey M.; Berns, Jeffrey S.; Parikh, Chirag R.

    2015-01-01

    Background and objectives Use of small changes in serum creatinine to diagnose AKI allows for earlier detection but may increase diagnostic false–positive rates because of inherent laboratory and biologic variabilities of creatinine. Design, setting, participants, & measurements We examined serum creatinine measurement characteristics in a prospective observational clinical reference cohort of 2267 adult patients with AKI by Kidney Disease Improving Global Outcomes creatinine criteria and used these data to create a simulation cohort to model AKI false–positive rates. We simulated up to seven successive blood draws on an equal population of hypothetical patients with unchanging true serum creatinine values. Error terms generated from laboratory and biologic variabilities were added to each simulated patient’s true serum creatinine value to obtain the simulated measured serum creatinine for each blood draw. We determined the proportion of patients who would be erroneously diagnosed with AKI by Kidney Disease Improving Global Outcomes creatinine criteria. Results Within the clinical cohort, 75.0% of patients received four serum creatinine draws within at least one 48-hour period during hospitalization. After four simulated creatinine measurements that accounted for laboratory variability calculated from assay characteristics and 4.4% of biologic variability determined from the clinical cohort and publicly available data, the overall false–positive rate for AKI diagnosis was 8.0% (interquartile range =7.9%–8.1%), whereas patients with true serum creatinine ≥1.5 mg/dl (representing 21% of the clinical cohort) had a false–positive AKI diagnosis rate of 30.5% (interquartile range =30.1%–30.9%) versus 2.0% (interquartile range =1.9%–2.1%) in patients with true serum creatinine values <1.5 mg/dl (P<0.001). Conclusions Use of small serum creatinine changes to diagnose AKI is limited by high false–positive rates caused by inherent variability of serum

  11. A Discovery of a Candidate Companion to a Transiting System KOI-94: A Direct Imaging Study for a Possibility of a False Positive

    NASA Technical Reports Server (NTRS)

    Takahashi, Yasuhiro; Narita, Norio; Hirano, Teruyuki; Kuzuhara, Masayuki; Tamura, Motohide; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Hashimoto, Jun; Sato, Bun'ei; Abe, Lyu; hide

    2013-01-01

    We report a discovery of a companion candidate around one of Kepler Objects of Interest (KOIs), KOI-94, and results of our quantitative investigation of the possibility that planetary candidates around KOI-94 are false positives. KOI-94 has a planetary system in which four planetary detections have been reported by Kepler, suggesting that this system is intriguing to study the dynamical evolutions of planets. However, while two of those detections (KOI-94.01 and 03) have been made robust by previous observations, the others (KOI-94.02 and 04) are marginal detections, for which future confirmations with various techniques are required. We have conducted high-contrast direct imaging observations with Subaru/HiCIAO in H band and detected a faint object located at a separation of approximately 0.6 sec from KOI-94. The object has a contrast of approximately 1 × 10(exp -3) in H band, and corresponds to an M type star on the assumption that the object is at the same distance of KOI-94. Based on our analysis, KOI-94.02 is likely to be a real planet because of its transit depth, while KOI-94.04 can be a false positive due to the companion candidate. The success in detecting the companion candidate suggests that high-contrast direct imaging observations are important keys to examine false positives of KOIs. On the other hand, our transit light curve reanalyses lead to a better period estimate of KOI-94.04 than that on the KOI catalogue and show that the planetary candidate has the same limb darkening parameter value as the other planetary candidates in the KOI-94 system, suggesting that KOI-94.04 is also a real planet in the system.

  12. An Evaluation of Unit and ½ Mass Correction Approaches as a Means of Minimizing the False Positives Produced by M+2 species in US EPA Method 200.8 using ICP-MS (webinar presentation)

    EPA Science Inventory

    Rare earth elements (REE) and certain alkaline earths can produce M+2 interferences in ICP-MS because they have sufficiently low second ionization energies. Four REEs (150Sm, 150Nd, 156Gd and 156Dy) produce false positives on 75As and 78Se and 132Ba can produce a false positive ...

  13. Limits of intravascular contrast extravasation on computed tomography scan to define the need for pelvic angioembolization in pelvic blunt trauma: a specific assessment on the risk of false-positives.

    PubMed

    Ramin, Séverin; Hermida, Margaux; Millet, Ingrid; Murez, Thibault; Monnin, Valérie; Hamoui, Mazen; Capdevila, Xavier; Charbit, Jonathan

    2018-06-12

    The objective was to assess the predictive performance of different intravascular contrast extravasation (ICE) characteristics for need for pelvic transarterial embolization (TAE) to determine the risk factors of false-positives. A retrospective study was performed in our trauma center between 2010 and 2015. All severe trauma patients with pelvic fracture were included. Pelvic ICE characteristics on computed tomography (CT) scan were studied: arterial (aSICE), portal surface (pSICE), and extension (exSICE) anatomic relationships. The overall predictive performance of ICE surfaces for pelvic TAE was analyzed using receiver operating characteristic curves. The analysis focused on risk factors for false-positives. Among 311 severe trauma patients with pelvic ring fracture (mean age, 42 ± 19 years, mean Injury Severity Score, 27 ± 19), 94 (30%) had at least one pelvic ICE on the initial CT scan. Patients requiring pelvic TAE had significantly larger aSICE and pSICE than others (P=0.001 and P=0.035, respectively). The overall ability of ICE surfaces to predict pelvic TAE was modest (aSICE AUC, 0.76 [95% CI, 0.64-0.90]; P=0.011) or non-significant (pSICE and exSICE). The high-sensitivity threshold was defined as aSICE ≥20 mm. Using this threshold, 76% of patients were false-positives. Risk factors for false-positives were: admission systolic blood pressure ≥90 mmHg (63% versus 20%; P=0.03) and low transfusion needs (63% versus 10%; P=0.009), extravasation in contact with complex bone fracture (78% versus 30%; P=0.008) or the absence of a direct relationship between extravasation and a large retroperitoneal hematoma (100% versus 38%; P<0.001). A significant pelvic ICE during the arterial phase does not guarantee the need for pelvic TAE. Three-quarter of patients with aSICE ≥20 mm did not need pelvic TAE. Several complementary CT scan criteria will help to identify this risk of false-positives to determine adequate hemostatic pelvic procedures.This work is an

  14. On the occurrence of false positives in tests of migration under an isolation with migration model

    PubMed Central

    Hey, Jody; Chung, Yujin; Sethuraman, Arun

    2015-01-01

    The population genetic study of divergence is often done using a Bayesian genealogy sampler, like those implemented in IMa2 and related programs, and these analyses frequently include a likelihood-ratio test of the null hypothesis of no migration between populations. Cruickshank and Hahn (2014, Molecular Ecology, 23, 3133–3157) recently reported a high rate of false positive test results with IMa2 for data simulated with small numbers of loci under models with no migration and recent splitting times. We confirm these findings and discover that they are caused by a failure of the assumptions underlying likelihood ratio tests that arises when using marginal likelihoods for a subset of model parameters. We also show that for small data sets, with little divergence between samples from two populations, an excellent fit can often be found by a model with a low migration rate and recent splitting time and a model with a high migration rate and a deep splitting time. PMID:26456794

  15. Arousal—But Not Valence—Reduces False Memories at Retrieval

    PubMed Central

    Mirandola, Chiara; Toffalini, Enrico

    2016-01-01

    Mood affects both memory accuracy and memory distortions. However, some aspects of this relation are still poorly understood: (1) whether valence and arousal equally affect false memory production, and (2) whether retrieval-related processes matter; the extant literature typically shows that mood influences memory performance when it is induced before encoding, leaving unsolved whether mood induced before retrieval also impacts memory. We examined how negative, positive, and neutral mood induced before retrieval affected inferential false memories and related subjective memory experiences. A recognition-memory paradigm for photographs depicting script-like events was employed. Results showed that individuals in both negative and positive moods–similar in arousal levels–correctly recognized more target events and endorsed fewer false memories (and these errors were linked to remember responses less frequently), compared to individuals in neutral mood. This suggests that arousal (but not valence) predicted memory performance; furthermore, we found that arousal ratings provided by participants were more adequate predictors of memory performance than their actual belonging to either positive, negative or neutral mood groups. These findings suggest that arousal has a primary role in affecting memory, and that mood exerts its power on true and false memory even when induced at retrieval. PMID:26938737

  16. GRANULOMATOUS ENCEPHALOMYELITIS IN A FALSE GHARIAL (TOMISTOMA SCHLEGELII) ASSOCIATED WITH A NOVEL CHLAMYDIA SPECIES.

    PubMed

    Bercier, Marjorie; Heard, Darryl J; Goe, Alexandra M; Epperson, Ember; Abbott, Jeffrey R; Childress, April L; Wellehan, James F X

    2017-06-01

    A 5-yr-old, captive, hatched, female false gharial (Tomistoma schlegelii) presented with a 1-mo history of cervical spinal curvature. Antemortem diagnostics, including blood work, electromyography, muscle biopsies, and advanced imaging tests, were either within reference ranges or did not identify any specific etiology. Necropsy revealed extensive, marked, chronic granulomatous encephalomyelitis along with neuronal necrosis, rarefaction, gliosis, and astrocytosis of the white and gray matter of the cerebrum, cerebellum, brainstem, and spinal cord. Pan-chlamydiae polymerase chain reaction protocols for the 16S ribosomal RNA and ompA genes were performed on samples of spinal cord and brain, and both resulted in amplicons. Sequencing of the products revealed that they were positive for a novel Chlamydia species. Infections by members of the phylum Chlamydiae have been reported in a diverse range of vertebrate hosts, including crocodilians. Chlamydia spp. infections are likely underdiagnosed because of a paucity of diagnostic techniques specific for detection. This is the first case report of a novel Chlamydia species associated with severe granulomatous encephalomyelitis in a false gharial.

  17. Underpowered samples, false negatives, and unconscious learning.

    PubMed

    Vadillo, Miguel A; Konstantinidis, Emmanouil; Shanks, David R

    2016-02-01

    The scientific community has witnessed growing concern about the high rate of false positives and unreliable results within the psychological literature, but the harmful impact of false negatives has been largely ignored. False negatives are particularly concerning in research areas where demonstrating the absence of an effect is crucial, such as studies of unconscious or implicit processing. Research on implicit processes seeks evidence of above-chance performance on some implicit behavioral measure at the same time as chance-level performance (that is, a null result) on an explicit measure of awareness. A systematic review of 73 studies of contextual cuing, a popular implicit learning paradigm, involving 181 statistical analyses of awareness tests, reveals how underpowered studies can lead to failure to reject a false null hypothesis. Among the studies that reported sufficient information, the meta-analytic effect size across awareness tests was d z = 0.31 (95 % CI 0.24-0.37), showing that participants' learning in these experiments was conscious. The unusually large number of positive results in this literature cannot be explained by selective publication. Instead, our analyses demonstrate that these tests are typically insensitive and underpowered to detect medium to small, but true, effects in awareness tests. These findings challenge a widespread and theoretically important claim about the extent of unconscious human cognition.

  18. Positive Psychology and Adolescent Mental Health: False Promise or True Breakthrough?

    ERIC Educational Resources Information Center

    Kelley, Thomas M.

    2004-01-01

    The emerging field of positive psychology has pledged to improve the mental health of American adolescents. Yet, without a principle-based conceptual foundation to guide its study of optimal youth functioning, positive psychology will ultimately fail to keep its promise. This paper suggests that the principles of Mind, Thought and Consciousness…

  19. Competitive binding experiments can reduce the false positive results of affinity-based ultrafiltration-HPLC: A case study for identification of potent xanthine oxidase inhibitors from Perilla frutescens extract.

    PubMed

    Wang, Zhiqiang; Kwon, Shin Hwa; Hwang, Seung Hwan; Kang, Young-Hee; Lee, Jae-Yong; Lim, Soon Sung

    2017-03-24

    The purpose of this study was to assess the possibility of using competitive binding experiments with ultrafiltration-HPLC analysis to identify potent xanthine oxidase (XO) inhibitors from the Perilla frutescens extract as an attempt to reduce the number of false positive results. To isolate the enzyme-ligand complex from unbound compounds, the P. frutescens extract was either incubated in the absence of XO, in the presence of XO, or with the active site blocked XO before the ultrafiltration was performed. Allopurinaol was used as the XO active site blocker. The unbound compounds were subjected to HPLC analysis. The degree of total binding (TBD) and degree of specific binding (SBD) of each compound were calculated using the peak areas. TBD represents the binding affinities of compounds from the P. frutescens extract for the XO binding site. SBD represents the XO competitive binding between allopurinol and ligands from the extract samples. Two criteria were applied to select putative targets that could help avoid false positives. These include TBD>30% and SBD>10%. Using that approach, kaempferol-3-O-rutinoside, rosmarinic acid, methyl-rosmarinic acid, apigenin, and 4',5,7-trimethoxyflavone were identified, from total 11 compounds, as potent XO inhibitors. Finally, apigenin, 4',5,7-trimethoxyflavone, and luteolin were XO inhibitors verified through an XO inhibition assay and structural simulation of the complex. These results showed that the newly developed strategy has the advantage that the number of targets identified via ultrafiltration-HPLC can be narrowed from many false positives. However, not all false positives can be eliminated with this approach. Some potent inhibitors might also be excluded with the use of this method. The limitations of this method are also discussed herein. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Responses to false physiological feedback in individuals with panic attacks and elevated anxiety sensitivity.

    PubMed

    Story, Tyler J; Craske, Michelle G

    2008-09-01

    Participants with elevated anxiety sensitivity and a history of panic attacks were compared to a low anxiety comparison group with respect to physiological and subjective reactivity to false heart-rate feedback and reactivity to a priming procedure. Whereas accurate heart-rate feedback elicited minimal responses, participants across groups showed significant physiological and subjective responses to false feedback. High risk and low risk participants did not differ in heart-rate responses to false feedback, though panic attack frequency did predict physiological and subjective reactions to false feedback in the high risk group. Self-reported nonspecific anxiety was significantly higher in high risk female participants than in low risk female participants, while males did not different in general subjective anxiety. However, high risk participants reported more panic-specific symptoms during the false feedback task than low risk participants, regardless of the sex of the participant. Therefore, although the experimental paradigm appeared to trigger nonspecific anxiety in high risk female participants, panic attack symptoms in reaction to the task were specific to risk group, not sex, and consistent with hypotheses. Surprisingly, the priming procedure did not influence physiological or subjective responses to false feedback in either group. These results raise additional questions regarding the process and impact of interception in individuals with panic attacks, and suggest that false perception of internal changes may contribute to risk for panic disorder when exposed to believable cues.

  1. Analysis of false results in a series of 835 fine needle aspirates of breast lesions.

    PubMed

    Willis, S L; Ramzy, I

    1995-01-01

    To analyze cases of false diagnoses from a large series to help increase the accuracy of fine needle aspiration of palpable breast lesions. The results of FNA of 835 palpable breast lesions were analyzed to determine the reasons for false positive, false negative and false suspicious diagnoses. Of the 835 aspirates, 174 were reported as positive, 549 as negative and 66 as suspicious or atypical but not diagnostic of malignancy. Forty-six cases were considered unsatisfactory. Tissue was available for comparison in 286 cases. The cytologic diagnoses in these cases were reported as follows: positive, 125 (43.7%); suspicious, 33 (11.5%); atypical, 18 (6.2%); negative, 92 (32%); and unsatisfactory, 18 (6.2%). There was one false positive diagnosis, yielding a false positive rate of 0.8%. This lesion was a case of fibrocystic change with hyperplasia, focal fat necrosis and reparative atypia. There were 14 false negative cases, resulting in a false negative rate of 13.2%. Nearly all these cases were sampling errors and included infiltrating ductal carcinomas (9), ductal carcinomas in situ (2), infiltrating lobular carcinomas (2) and tubular carcinoma (1). Most of the suspicious and atypical lesions proved to be carcinomas (35/50). The remainder were fibroadenomas (6), fibrocystic change (4), gynecomastia (2), adenosis (2) and granulomatous mastitis (1). A positive diagnosis of malignancy by FNA is reliable in establishing the diagnosis and planning the treatment of breast cancer. The false-positive rate is very low, with only a single case reported in 835 aspirates. Most false negatives are due to sampling and not to interpretive difficulties. The category "suspicious but not diagnostic of malignancy" serves a useful purpose in management of patients with breast lumps.

  2. False Memory in Adults With ADHD: A Comparison Between Subtypes and Normal Controls.

    PubMed

    Soliman, Abdrabo Moghazy; Elfar, Rania Mohamed

    2017-10-01

    To examine the performance on the Deese-Roediger-McDermott task of adults divided into ADHD subtypes and compares their performance to that of healthy controls to examine whether adults with ADHD are more susceptible to the production of false memories under experimental conditions. A total of 128 adults with ADHD (50% females), classified into three Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV-TR) subtypes, were compared with 48 controls. The results indicated that the ADHD participants recalled and recognized fewer studied words than the controls, the ADHD groups produced more false memories than the control group, no differences in either the false positives or the false negatives. The ADHD-combined (ADHD-CT) group recognized significantly more critical words than the control, ADHD-predominantly inattentive (ADHD-IA), and ADHD-predominantly hyperactive-impulsive (ADHD-HI) groups. The ADHD groups recalled and recognized more false positives, were more confident in their false responses, and displayed more knowledge corruption than the controls. The ADHD-CT group recalled and recognized more false positives than the other ADHD groups. The adults with ADHD have more false memories than the controls and that false memory formation varied with the ADHD subtypes.

  3. The distinctiveness heuristic in false recognition and false recall.

    PubMed

    McCabe, David P; Smith, Anderson D

    2006-07-01

    The effects of generative processing on false recognition and recall were examined in four experiments using the Deese-Roediger-McDermott false memory paradigm (Deese, 1959; Roediger & McDermott, 1995). In each experiment, a Generate condition in which subjects generated studied words from audio anagrams was compared to a Control condition in which subjects simply listened to studied words presented normally. Rates of false recognition and false recall were lower for critical lures associated with generated lists, than for critical lures associated with control lists, but only in between-subjects designs. False recall and recognition did not differ when generate and control conditions were manipulated within-subjects. This pattern of results is consistent with the distinctiveness heuristic (Schacter, Israel, & Racine, 1999), a metamemorial decision-based strategy whereby global changes in decision criteria lead to reductions of false memories. This retrieval-based monitoring mechanism appears to operate in a similar fashion in reducing false recognition and false recall.

  4. Selecting At-Risk First-Grade Readers for Early Intervention: Eliminating False Positives and Exploring the Promise of a Two-Stage Gated Screening Process

    ERIC Educational Resources Information Center

    Compton, Donald L.; Fuchs, Douglas; Fuchs, Lynn S.; Bouton, Bobette; Gilbert, Jennifer K.; Barquero, Laura A.; Cho, Eunsoo; Crouch, Robert C.

    2010-01-01

    The purposes of this study were (a) to identify measures that when added to a base 1st-grade screening battery help eliminate false positives and (b) to investigate gains in efficiency associated with a 2-stage gated screening procedure. We tested 355 children in the fall of 1st grade and assessed for reading difficulty at the end of 2nd grade.…

  5. The Relations Between False Positive and Negative Screens and Smoking Cessation and Relapse in the National Lung Screening Trial: Implications for Public Health.

    PubMed

    Clark, Melissa A; Gorelick, Jeremy J; Sicks, JoRean D; Park, Elyse R; Graham, Amanda L; Abrams, David B; Gareen, Ilana F

    2016-01-01

    Lung screening is an opportunity for smoking cessation and relapse prevention, but smoking behaviors may differ across screening results. Changes in smoking were evaluated among 18 840 current and former smokers aged 55-74 scheduled to receive three annual lung screenings. Participants were randomized to low-dose computed tomography or single-view chest radiography in the American College of Radiology/National Lung Screening Trial. Outcome measures included point and sustained (6-month) abstinence and motivation to quit among smokers; and relapse among smokers who quit during follow-up, recent quitters (quit < 6 months), and long-term former smokers (quit ≥ 6 months). During five years of follow-up, annual point prevalence quit rates ranged from 11.6%-13.4%; 48% of current smokers reported a quit attempt and 7% of long-term former smokers relapsed. Any false positive screening result was associated with subsequent increased point (multivariable hazard ratio HR = 1.23, 95% CI = 1.13, 1.35) and sustained (HR = 1.28, 95% CI = 1.15, 1.43) abstinence among smokers. Recent quitters with ≥1 false positive screen were less likely to relapse (HR = 0.72, 95% CI = 0.54, 0.96). Screening result was not associated with relapse among long-term former smokers or among baseline smokers who quit during follow-up. A false positive screen was associated with increased smoking cessation and less relapse among recent quitters. Consistently negative screens were not associated with greater relapse among long-term former smokers. Given the Affordable Care Act requires most health plans to cover smoking cessation and lung screening, the impact and cost-effectiveness of lung screening could be further enhanced with the addition of smoking cessation interventions. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Belief and sign, true and false: the unique of false belief reasoning.

    PubMed

    Zhang, Ting; Zhang, Qin; Li, Yiyuan; Long, Changquan; Li, Hong

    2013-11-01

    For a long time, a controversy has been proposed that whether the process of theory of mind is a result of domain-specific or domain-general changes (Wellman in The handbook of childhood cognitive development. Blackwell Publication, New Jersey, 2011). This event-related potential study explored the neural time course of domain-general and domain-specific components in belief reasoning. Fourteen participants completed location transfer false belief (FB), true belief (TB), false sign (FS) and true sign (TS) tasks, in which two pictures told a story related to a dog that ran from a green into a red box. In the TB and FB tasks, a boy saw or did not see the transfer of the dog, respectively. In the FS and TS tasks, an arrow that pointed to the green box either altered its direction to the red box or did not alter following the transfer of the dog. Participants then inferred where the boy thought of, or the arrow indicated the location of the dog. FB and TB reasoning elicited lower N2 amplitudes than FS and TS reasoning, which is associated with domain-general components, the detection, and classification. The late slow wave (LSW) for FB was more positive at frontal, central, and parietal sites than FS because of the domain-specific component involved in FB reasoning. However, the LSW was less positive for TB than for FB but did not differ from the TS condition, which implies that mental representation might not be involved in TB reasoning.

  7. Computerized detection of unruptured aneurysms in MRA images: reduction of false positives using anatomical location features

    NASA Astrophysics Data System (ADS)

    Uchiyama, Yoshikazu; Gao, Xin; Hara, Takeshi; Fujita, Hiroshi; Ando, Hiromichi; Yamakawa, Hiroyasu; Asano, Takahiko; Kato, Hiroki; Iwama, Toru; Kanematsu, Masayuki; Hoshi, Hiroaki

    2008-03-01

    The detection of unruptured aneurysms is a major subject in magnetic resonance angiography (MRA). However, their accurate detection is often difficult because of the overlapping between the aneurysm and the adjacent vessels on maximum intensity projection images. The purpose of this study is to develop a computerized method for the detection of unruptured aneurysms in order to assist radiologists in image interpretation. The vessel regions were first segmented using gray-level thresholding and a region growing technique. The gradient concentration (GC) filter was then employed for the enhancement of the aneurysms. The initial candidates were identified in the GC image using a gray-level threshold. For the elimination of false positives (FPs), we determined shape features and an anatomical location feature. Finally, rule-based schemes and quadratic discriminant analysis were employed along with these features for distinguishing between the aneurysms and the FPs. The sensitivity for the detection of unruptured aneurysms was 90.0% with 1.52 FPs per patient. Our computerized scheme can be useful in assisting the radiologists in the detection of unruptured aneurysms in MRA images.

  8. Combined use of reverse transcriptase polymerase chain reaction and flow cytometry to study minimal residual disease in Philadelphia positive acute lymphoblastic leukemia.

    PubMed

    Muñoz, L; López, O; Martino, R; Brunet, S; Bellido, M; Rubiol, E; Sierra, J; Nomdedéu, J F

    2000-07-01

    The Philadelphia chromosome in acute lymphoblastic leukemia (Ph+ ALL) is associated with a poor prognosis given the high frequency of chemoresistance and leukemia relapse. Minimal residual disease (MRD) detection before cytogenetic and hematologic relapse could be useful in early therapy. The most suitable methods for detecting MRD in Ph+ ALL are flow cytometry (FC) and reverse transcriptase polymerase chain reaction (RT-PCR). However, since both techniques carry the risk of false-negative results the combined use of these two techniques could overcome this problem. We report our experience using this approach in 47 bone marrow samples obtained from 10 Ph+ ALL patients. Twenty-seven marrow aspirates were taken from patients in clinical remission (CR). The samples were considered positive for MRD by FC when two conditions were met: 1) detection of an abnormal B-cell differentiation pattern and 2) presence of more than 1x10(-3) cells coexpressing CD22/CD34/CD45 or CD66/CD34/CD10. After FC analysis, RNA was purified using standard methods. FC was positive in 23/27 samples in CR (sensitivity 85%). RT-PCR was successfully performed in 23 samples in CR. RT-PCR was positive in 18/23 samples (sensitivity 78%). There were 5 samples with discordant results. FC was positive in 3 samples with a negative RT-PCR and FC was negative in 2 samples with a positive RT. All the 10 patients relapsed and only 1 is currently alive after an allogeneic stem cell transplantation (alloSCT). The median (range) time from MRD detection to relapse in patients treated with chemotherapy was 42 (39-71) days. These data suggest that RT-PCR may be negative despite the presence of neoplastic cells identified by their immunophenotypic traits. We conclude that immunologic and molecular techniques can be used in tandem for monitoring MRD in Ph+ ALL.

  9. Use of the false discovery rate for evaluating clinical safety data.

    PubMed

    Mehrotra, Devan V; Heyse, Joseph F

    2004-06-01

    Clinical adverse experience (AE) data are routinely evaluated using between group P values for every AE encountered within each of several body systems. If the P values are reported and interpreted without multiplicity considerations, there is a potential for an excess of false positive findings. Procedures based on confidence interval estimates of treatment effects have the same potential for false positive findings as P value methods. Excess false positive findings can needlessly complicate the safety profile of a safe drug or vaccine. Accordingly, we propose a novel method for addressing multiplicity in the evaluation of adverse experience data arising in clinical trial settings. The method involves a two-step application of adjusted P values based on the Benjamini and Hochberg false discovery rate (FDR). Data from three moderate to large vaccine trials are used to illustrate our proposed 'Double FDR' approach, and to reinforce the potential impact of failing to account for multiplicity. This work was in collaboration with the late Professor John W. Tukey who coined the term 'Double FDR'.

  10. Mood-congruent true and false memory: effects of depression.

    PubMed

    Howe, Mark L; Malone, Catherine

    2011-02-01

    The Deese/Roediger-McDermott paradigm was used to investigate the effect of depression on true and false recognition. In this experiment true and false recognition was examined across positive, neutral, negative, and depression-relevant lists for individuals with and without a diagnosis of major depressive disorder. Results showed that participants with major depressive disorder falsely recognised significantly more depression-relevant words than non-depressed controls. These findings also parallel recent research using recall instead of recognition and show that there are clear mood congruence effects for depression on false memory performance. © 2011 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business

  11. Disfluent presentations lead to the creation of more false memories.

    PubMed

    Sanchez, Christopher A; Naylor, Jamie S

    2018-01-01

    The creation of false memories within the Deese-Roediger-McDermott (DRM) paradigm has been shown to be sensitive to many factors such as task instructions, participant mood, or even presentation modality. However, do other simple perceptual differences also impact performance on the DRM and the creation of false memories? This study explores the potential impact of changes in perceptual disfluency on DRM performance. To test for a potential influence of disfluency on false memory creation, participants viewed lists under either perceptually disfluent conditions or not. Results indicated that disfluency did significantly impact performance in the DRM paradigm; more disfluent presentations significantly increased the recall and recognition of unpresented information, although they did not impact recall or recognition of presented information. Thus, although disfluency did impact performance, disfluency did not produce a positive benefit related to overall task performance. This finding instead suggests that more disfluent presentations can increase the likelihood that false memories are created, and provide little positive performance benefit.

  12. Disfluent presentations lead to the creation of more false memories

    PubMed Central

    Naylor, Jamie S.

    2018-01-01

    The creation of false memories within the Deese-Roediger-McDermott (DRM) paradigm has been shown to be sensitive to many factors such as task instructions, participant mood, or even presentation modality. However, do other simple perceptual differences also impact performance on the DRM and the creation of false memories? This study explores the potential impact of changes in perceptual disfluency on DRM performance. To test for a potential influence of disfluency on false memory creation, participants viewed lists under either perceptually disfluent conditions or not. Results indicated that disfluency did significantly impact performance in the DRM paradigm; more disfluent presentations significantly increased the recall and recognition of unpresented information, although they did not impact recall or recognition of presented information. Thus, although disfluency did impact performance, disfluency did not produce a positive benefit related to overall task performance. This finding instead suggests that more disfluent presentations can increase the likelihood that false memories are created, and provide little positive performance benefit. PMID:29370255

  13. Upper Limb Neural Tension and Seated Slump Tests: The False Positive Rate among Healthy Young Adults without Cervical or Lumbar Symptoms.

    PubMed

    Davis, D Scott; Anderson, Ila Beth; Carson, Mary Grace; Elkins, Caroline L; Stuckey, Lindsey B

    2008-01-01

    This study examined the false positive rate of the upper limb neural tension test (ULNTT) and seated slump test (SST) among healthy young adults with no history of cervical, lumbar, or peripheral symptoms. Eighty-four subjects (27 men and 57 women) with a mean age of 22.9 years participated in the investigation. All participants completed a screening questionnaire designed to exclude subjects with a history of cervical or lumbar spine pain or injury, or upper or lower extremity neurological symptoms. The ULNTT and the SST were performed on the left upper and lower extremity of each participant. Of the 84 participants tested, 73 (86.9%) were found to have a positive ULNTT at some point in the available range of elbow extension. Twenty-eight (33.3%) of the 84 subjects had a positive SST at some point in the available range of knee extension. The mean knee extension angle for those subjects with a positive SST was 15.1 degrees with a 95% confidence interval (CI) of 12.3 and 19.7 degrees . The mean elbow extension angle for those with a positive ULNTT was 49.4 degrees with a 95% CI of 44.8 and 54.0 degrees . The number of positive tests for both the ULNTT and the SST was found to be high in this sample of asymptomatic healthy young adults. Based on the results of this investigation, the authors suggest that the current criteria for determining a positive test for both the ULNTT and the SST should be examined using the proposed range of motion cut-off scores.

  14. The effect of addition of primary positive salts, complex salt, on the ionic strength and rate constant at various temperatures by reaction kinetics

    NASA Astrophysics Data System (ADS)

    Kurade, S. S.; Ramteke, A. A.

    2018-05-01

    In this work, we have investigated the rate of reaction by using ionic strength at different temperatures. The main goal of this experiment is to determine the relation between ionic strength with reaction rate, reaction time and rate constant with temperature. It is observed that the addition of positive salt indicate the increasing ionic strength with increase in run time at various temperatures. Thus the temperature affects the speed of reaction and mechanism by which chemical reaction occurs and time variable plays vital role in the progress of reaction at different temperatures.

  15. Computational investigation of kinetics of cross-linking reactions in proteins: importance in structure prediction.

    PubMed

    Bandyopadhyay, Pradipta; Kuntz, Irwin D

    2009-01-01

    The determination of protein structure using distance constraints is a new and promising field of study. One implementation involves attaching residues of a protein using a cross-linking agent, followed by protease digestion, analysis of the resulting peptides by mass spectroscopy, and finally sequence threading to detect the protein folds. In the present work, we carry out computational modeling of the kinetics of cross-linking reactions in proteins using the master equation approach. The rate constants of the cross-linking reactions are estimated using the pKas and the solvent-accessible surface areas of the residues involved. This model is tested with fibroblast growth factor (FGF) and cytochrome C. It is consistent with the initial experimental rate data for individual lysine residues for cytochrome C. Our model captures all observed cross-links for FGF and almost 90% of the observed cross-links for cytochrome C, although it also predicts cross-links that were not observed experimentally (false positives). However, the analysis of the false positive results is complicated by the fact that experimental detection of cross-links can be difficult and may depend on specific experimental conditions such as pH, ionic strength. Receiver operator characteristic plots showed that our model does a good job in predicting the observed cross-links. Molecular dynamics simulations showed that for cytochrome C, in general, the two lysines come closer for the observed cross-links as compared to the false positive ones. For FGF, no such clear pattern exists. The kinetic model and MD simulation can be used to study proposed cross-linking protocols.

  16. On the Implications of a Sex Difference in the Reaction Times of Sprinters at the Beijing Olympics

    PubMed Central

    Lipps, David B.; Galecki, Andrzej T.; Ashton-Miller, James A.

    2011-01-01

    Elite sprinters offer insights into the fastest whole body auditory reaction times. When, however, is a reaction so fast that it represents a false start? Currently, a false start is awarded if an athlete increases the force on their starting block above a given threshold before 100 ms has elapsed after the starting gun. To test the hypothesis that the fastest valid reaction times of sprinters really is 100 ms and that no sex difference exists in that time, we analyzed the fastest reaction times achieved by each of the 425 male and female sprinters who competed at the 2008 Beijing Olympics. After power transformation of the skewed data, a fixed effects ANOVA was used to analyze the effects of sex, race, round and lane position. The lower bounds of the 95, 99 and 99.9% confidence intervals were then calculated and back transformed. The mean fastest reaction time recorded by men was significantly faster than women (p<0.001). At the 99.9% confidence level, neither men nor women can react in 100 ms, but they can react in as little as 109 ms and 121 ms, respectively. However, that sex difference in reaction time is likely an artifact caused by using the same force threshold in women as men, and it permits a woman to false start by up to 21 ms without penalty. We estimate that female sprinters would have similar reaction times to male sprinters if the force threshold used at Beijing was lowered by 22% in order to account for their lesser muscle strength. PMID:22039438

  17. Computer-aided mass detection in mammography: False positive reduction via gray-scale invariant ranklet texture features

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Masotti, Matteo; Lanconelli, Nico; Campanini, Renato

    In this work, gray-scale invariant ranklet texture features are proposed for false positive reduction (FPR) in computer-aided detection (CAD) of breast masses. Two main considerations are at the basis of this proposal. First, false positive (FP) marks surviving our previous CAD system seem to be characterized by specific texture properties that can be used to discriminate them from masses. Second, our previous CAD system achieves invariance to linear/nonlinear monotonic gray-scale transformations by encoding regions of interest into ranklet images through the ranklet transform, an image transformation similar to the wavelet transform, yet dealing with pixels' ranks rather than with theirmore » gray-scale values. Therefore, the new FPR approach proposed herein defines a set of texture features which are calculated directly from the ranklet images corresponding to the regions of interest surviving our previous CAD system, hence, ranklet texture features; then, a support vector machine (SVM) classifier is used for discrimination. As a result of this approach, texture-based information is used to discriminate FP marks surviving our previous CAD system; at the same time, invariance to linear/nonlinear monotonic gray-scale transformations of the new CAD system is guaranteed, as ranklet texture features are calculated from ranklet images that have this property themselves by construction. To emphasize the gray-scale invariance of both the previous and new CAD systems, training and testing are carried out without any in-between parameters' adjustment on mammograms having different gray-scale dynamics; in particular, training is carried out on analog digitized mammograms taken from a publicly available digital database, whereas testing is performed on full-field digital mammograms taken from an in-house database. Free-response receiver operating characteristic (FROC) curve analysis of the two CAD systems demonstrates that the new approach achieves a higher reduction of FP

  18. The effect of mood on false memory for emotional DRM word lists.

    PubMed

    Zhang, Weiwei; Gross, Julien; Hayne, Harlene

    2017-04-01

    In the present study, we investigated the effect of participants' mood on true and false memories of emotional word lists in the Deese-Roediger-McDermott (DRM) paradigm. In Experiment 1, we constructed DRM word lists in which all the studied words and corresponding critical lures reflected a specified emotional valence. In Experiment 2, we used these lists to assess mood-congruent true and false memory. Participants were randomly assigned to one of three induced-mood conditions (positive, negative, or neutral) and were presented with word lists comprised of positive, negative, or neutral words. For both true and false memory, there was a mood-congruent effect in the negative mood condition; this effect was due to a decrease in true and false recognition of the positive and neutral words. These findings are consistent with both spreading-activation and fuzzy-trace theories of DRM performance and have practical implications for our understanding of the effect of mood on memory.

  19. A Segmented Neutron Detector with a High Position Resolution for the (p,pn) Reactions

    NASA Astrophysics Data System (ADS)

    Kubota, Yuki; Sasano, Masaki; Uesaka, Tomohiro; Dozono, Masanori; Itoh, Masatoshi; Kawase, Shoichiro; Kobayashi, Motoki; Lee, CheongSoo; Matsubara, Hiroaki; Miki, Kenjiro; Miya, Hiroyuki; Ota, Shinsuke; Sekiguchi, Kimiko; Shima, Tatsushi; Taguchi, Takahiro; Tamii, Atsushi; Tang, Tsz Leung; Tokieda, Hiroshi; Wakasa, Tomotsugu; Wakui, Takashi; Yasuda, Jumpei; Zenihiro, Juzo

    We are developing a neutron detector with a high position resolution to study the single particle properties of nuclei by the knockout (p,pn) reaction at intermediate energies. We constructed a prototype detector consisting of plastic scintillating fibers and multi-anode photomultiplier tubes (PMTs). Test experiments using 200- and 70-MeV proton and 199-, 188-, 68-, and 50-MeV neutron were performed for characterizing its performance. Preliminary results show that a position resolution of about 3 mm at full-width at half-maximum (FWHM) is realized as designed. The resulting separation-energy resolution to be obtained for (p,pn) measurement would be 1 MeV in FWHM, when the detector is used at a distance of 2 m from the target for measuring the neutron momentum.

  20. Automated detection of masses on whole breast volume ultrasound scanner: false positive reduction using deep convolutional neural network

    NASA Astrophysics Data System (ADS)

    Hiramatsu, Yuya; Muramatsu, Chisako; Kobayashi, Hironobu; Hara, Takeshi; Fujita, Hiroshi

    2017-03-01

    Breast cancer screening with mammography and ultrasonography is expected to improve sensitivity compared with mammography alone, especially for women with dense breast. An automated breast volume scanner (ABVS) provides the operator-independent whole breast data which facilitate double reading and comparison with past exams, contralateral breast, and multimodality images. However, large volumetric data in screening practice increase radiologists' workload. Therefore, our goal is to develop a computer-aided detection scheme of breast masses in ABVS data for assisting radiologists' diagnosis and comparison with mammographic findings. In this study, false positive (FP) reduction scheme using deep convolutional neural network (DCNN) was investigated. For training DCNN, true positive and FP samples were obtained from the result of our initial mass detection scheme using the vector convergence filter. Regions of interest including the detected regions were extracted from the multiplanar reconstraction slices. We investigated methods to select effective FP samples for training the DCNN. Based on the free response receiver operating characteristic analysis, simple random sampling from the entire candidates was most effective in this study. Using DCNN, the number of FPs could be reduced by 60%, while retaining 90% of true masses. The result indicates the potential usefulness of DCNN for FP reduction in automated mass detection on ABVS images.

  1. 21 CFR 606.170 - Adverse reaction file.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Adverse reaction file. 606.170 Section 606.170... Adverse reaction file. (a) Records shall be maintained of any reports of complaints of adverse reactions... thorough investigation of each reported adverse reaction shall be made. A written report of the...

  2. Opportunity for information search and the effect of false heart rate feedback.

    PubMed

    Barefoot, John C; Straub, Ronald B

    2005-01-01

    The role of information search in the attribution of physiological states was investigated by manipulating the subject's opportunity for information search following the presentation of false information about his heart-rate reactions to photographs of female nudes. Consistent with the self-persuasion hypothesis proposed by Valins, the rated attractiveness of the slides was not affected by the false heart-rate feedback for those subjects who were prevented from visually searching the slides. Those subjects who had ample opportunity to view the slides rated those slides accompanied by false information of a heart-rate change as more attractive than those slides which were not paired with a change in heart rate.

  3. Screening for gonorrhoea using samples collected through the English national chlamydia screening programme and risk of false positives: a national survey of local authorities.

    PubMed

    Field, Nigel; Kennedy, Iain; Folkard, Kate; Duffell, Stephen; Town, Katy; Ison, Catherine A; Hughes, Gwenda

    2014-10-16

    To investigate use of dual tests for Chlamydia trachomatis and Neisseria gonorrhoeae on samples collected through the National Chlamydia Screening Programme (NCSP) in England. During May-July 2013, we delivered an online survey to commissioners of sexual health services in the 152 upper-tier English Local Authorities (LAs) who were responsible for commissioning chlamydia screening in people aged 15-24 years. (1) The proportion of English LAs using dual tests on samples collected by the NCSP; (2) The estimated number of gonorrhoea tests and false positives from samples collected by the NCSP, calculated using national surveillance data on the number of chlamydia tests performed, assuming the gonorrhoea prevalence to range between 0.1% and 1%, and test sensitivity and specificity of 99.5%. 64% (98/152) of LAs responded to this national survey; over half (53% (52/98)) reported currently using dual tests in community settings. There was no significant difference between LAs using and not using dual tests by chlamydia positivity, chlamydia diagnosis rate or population screening coverage. Although positive gonorrhoea results were confirmed with supplementary tests in 93% (38/41) of LAs, this occurred after patients were notified about the initial positive result in 63% (26/41). Approximately 450-4500 confirmed gonorrhoea diagnoses and 2300 false-positive screens might occur through use of dual tests on NCSP samples each year. Under reasonable assumptions, the positive predictive value of the screening test is 17-67%. Over half of English LAs already commission dual tests for samples collected by the NCSP. Gonorrhoea screening has been introduced alongside chlamydia screening in many low prevalence settings without a national evidence review or change of policy. We question the public health benefit here, and suggest that robust testing algorithms and clinical management pathways, together with rigorous evaluation, be implemented wherever dual tests are deployed

  4. Screening for gonorrhoea using samples collected through the English National Chlamydia Screening Programme and risk of false positives: a national survey of Local Authorities

    PubMed Central

    Field, Nigel; Kennedy, Iain; Folkard, Kate; Duffell, Stephen; Town, Katy; Ison, Catherine A; Hughes, Gwenda

    2014-01-01

    Objectives To investigate use of dual tests for Chlamydia trachomatis and Neisseria gonorrhoeae on samples collected through the National Chlamydia Screening Programme (NCSP) in England. Design and setting During May–July 2013, we delivered an online survey to commissioners of sexual health services in the 152 upper-tier English Local Authorities (LAs) who were responsible for commissioning chlamydia screening in people aged 15–24 years. Main outcome measures (1) The proportion of English LAs using dual tests on samples collected by the NCSP; (2) The estimated number of gonorrhoea tests and false positives from samples collected by the NCSP, calculated using national surveillance data on the number of chlamydia tests performed, assuming the gonorrhoea prevalence to range between 0.1% and 1%, and test sensitivity and specificity of 99.5%. Results 64% (98/152) of LAs responded to this national survey; over half (53% (52/98)) reported currently using dual tests in community settings. There was no significant difference between LAs using and not using dual tests by chlamydia positivity, chlamydia diagnosis rate or population screening coverage. Although positive gonorrhoea results were confirmed with supplementary tests in 93% (38/41) of LAs, this occurred after patients were notified about the initial positive result in 63% (26/41). Approximately 450–4500 confirmed gonorrhoea diagnoses and 2300 false-positive screens might occur through use of dual tests on NCSP samples each year. Under reasonable assumptions, the positive predictive value of the screening test is 17–67%. Conclusions Over half of English LAs already commission dual tests for samples collected by the NCSP. Gonorrhoea screening has been introduced alongside chlamydia screening in many low prevalence settings without a national evidence review or change of policy. We question the public health benefit here, and suggest that robust testing algorithms and clinical management pathways, together

  5. Mammography Clinical Image Quality and the False Positive Rate in a Canadian Breast Cancer Screening Program.

    PubMed

    Guertin, Marie-Hélène; Théberge, Isabelle; Zomahoun, Hervé Tchala Vignon; Dufresne, Michel-Pierre; Pelletier, Éric; Brisson, Jacques

    2018-05-01

    The study sought to determine if mammography quality is associated with the false positive (FP) rate in the Quebec breast cancer screening program in 2004 and 2005. Mammography quality of a random sample of screen-film mammograms was evaluated by an expert radiologist following the criteria of the Canadian Association of Radiologists. For each screening examination, scores ranging from 1 (poor quality) to 5 (excellent quality) were attributed for positioning, compression, contrast, exposure level, sharpness, and artifacts. A final overall quality score (lower or higher) was also given. Poisson regression models with robust estimation of variance and adjusted for potential confounding factors were used to assess associations of mammography quality with the FP rate. Among 1,209 women without cancer, there were 104 (8.6%) FPs. Lower overall mammography quality is associated with an increase in the FP rate (risk ratio [RR], 1.4; 95% confidence interval [CI], 1.0-2.1; P = .07) but this increase was not statistically significant. Artifacts were associated with an increase in the FP rate (RR, 2.1; 95% CI, 1.3-3.3; P = .01) whereas lower quality of exposure level was related to a reduction of the FP rate (RR, 0.4; 95% CI, 0.1-1.0; P = .01). Lower quality scores for all other quality attributes were related to a nonstatistically significant increase in the FP rate of 10%-30%. Artifacts can have a substantial effect on the FP rate. The effect of overall mammography quality on the FP rate may also be substantial and needs to be clarified. Copyright © 2017 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

  6. Pluto behaving badly: false beliefs and their consequences.

    PubMed

    Berkowitz, Shari R; Laney, Cara; Morris, Erin K; Garry, Maryanne; Loftus, Elizabeth F

    2008-01-01

    We exposed college students to suggestive materials in order to lead them to believe that, as children, they had a negative experience at Disneyland involving the Pluto character. A sizable minority of subjects developed a false belief or memory that Pluto had uncomfortably licked their ear. Suggestions about a positive experience with Pluto led to even greater acceptance of a lovable ear-licking episode. False beliefs and memories had repercussions; those seduced by the bad suggestions were not willing to pay as much for a Pluto souvenir. These findings are among the first to demonstrate that false beliefs can have repercussions for people, meaning that they can influence their later thoughts, beliefs, and behaviors.

  7. Blocking Mimicry Makes True and False Smiles Look the Same

    PubMed Central

    Rychlowska, Magdalena; Cañadas, Elena; Wood, Adrienne; Krumhuber, Eva G.; Fischer, Agneta; Niedenthal, Paula M.

    2014-01-01

    Recent research suggests that facial mimicry underlies accurate interpretation of subtle facial expressions. In three experiments, we manipulated mimicry and tested its role in judgments of the genuineness of true and false smiles. Experiment 1 used facial EMG to show that a new mouthguard technique for blocking mimicry modifies both the amount and the time course of facial reactions. In Experiments 2 and 3, participants rated true and false smiles either while wearing mouthguards or when allowed to freely mimic the smiles with or without additional distraction, namely holding a squeeze ball or wearing a finger-cuff heart rate monitor. Results showed that blocking mimicry compromised the decoding of true and false smiles such that they were judged as equally genuine. Together the experiments highlight the role of facial mimicry in judging subtle meanings of facial expressions. PMID:24670316

  8. Upper Limb Neural Tension and Seated Slump Tests: The False Positive Rate among Healthy Young Adults without Cervical or Lumbar Symptoms

    PubMed Central

    Davis, D. Scott; Anderson, Ila Beth; Carson, Mary Grace; Elkins, Caroline L.; Stuckey, Lindsey B.

    2008-01-01

    This study examined the false positive rate of the upper limb neural tension test (ULNTT) and seated slump test (SST) among healthy young adults with no history of cervical, lumbar, or peripheral symptoms. Eighty-four subjects (27 men and 57 women) with a mean age of 22.9 years participated in the investigation. All participants completed a screening questionnaire designed to exclude subjects with a history of cervical or lumbar spine pain or injury, or upper or lower extremity neurological symptoms. The ULNTT and the SST were performed on the left upper and lower extremity of each participant. Of the 84 participants tested, 73 (86.9%) were found to have a positive ULNTT at some point in the available range of elbow extension. Twenty-eight (33.3%) of the 84 subjects had a positive SST at some point in the available range of knee extension. The mean knee extension angle for those subjects with a positive SST was 15.1° with a 95% confidence interval (CI) of 12.3 and 19.7°. The mean elbow extension angle for those with a positive ULNTT was 49.4° with a 95% CI of 44.8 and 54.0°. The number of positive tests for both the ULNTT and the SST was found to be high in this sample of asymptomatic healthy young adults. Based on the results of this investigation, the authors suggest that the current criteria for determining a positive test for both the ULNTT and the SST should be examined using the proposed range of motion cut-off scores. PMID:19119402

  9. Facing the problem of "false positives": re-assessment and improvement of a multiplex RT-PCR procedure for the diagnosis of A. flavus mycotoxin producers.

    PubMed

    Degola, F; Berni, E; Spotti, E; Ferrero, I; Restivo, F M

    2009-02-28

    The aim of our research project was to consolidate a multiplex RT-PCR protocol to detect aflatoxigenic strains of Aspergillus flavus. Several independent A. flavus strains were isolated from corn and flour samples from the North of Italy and from three European countries. Aflatoxin producing/not producing phenotype was assessed by qualitative and quantitative assays at day five of growth in aflatoxin inducing conditions. Expression of 16 genes belonging to the aflatoxin cluster was assayed by multiplex or monomeric RT-PCR. There is a good correlation between gene expression and aflatoxin production. Strains that apparently transcribed all the relevant genes but did not release aflatoxin in the medium ("false positives") were re-assessed for mycotoxin production after extended growth in inducing condition. All the "false positive" strains in actual fact were positive when aflatoxin determination was performed after 10 days of growth. These strains should then be re-classified as "slow aflatoxin accumulators". To optimise the diagnostic procedure, a quintuplex RT-PCR procedure was designed consisting of a primer set directed against four informative aflatoxin cluster genes and the beta-tubulin gene as an internal amplification control. In conclusion we have provided evidence for the robustness and reliability of our RT-PCR protocol in discriminating mycotoxin producer from non-producer strains of A. flavus. and the molecular procedure we devised is a promising tool with which to screen and control the endemic population of A. flavus colonising different areas of the World.

  10. Determination of Double Bond Positions in Polyunsaturated Fatty Acids Using the Photochemical Paternò-Büchi Reaction with Acetone and Tandem Mass Spectrometry.

    PubMed

    Murphy, Robert C; Okuno, Toshiaki; Johnson, Christopher A; Barkley, Robert M

    2017-08-15

    The positions of double bonds along the carbon chain of methylene interrupted polyunsaturated fatty acids are unique identifiers of specific fatty acids derived from biochemical reactions that occur in cells. It is possible to obtain direct structural information as to these double bond positions using tandem mass spectrometry after collisional activation of the carboxylate anions of an acetone adduct at each of the double bond positions formed by the photochemical Paternò-Büchi reaction with acetone. This reaction can be carried out by exposing a small portion of an inline fused silica capillary to UV photons from a mercury vapor lamp as the sample is infused into the electrospray ion source of a mass spectrometer. Collisional activation of [M - H] - yields a series of reverse Paternò-Büchi reaction product ions that essentially are derived from cleavage of the original carbon-carbon double bonds that yield an isopropenyl carboxylate anion corresponding to each double bond location. Aldehydic reverse Paternò-Büchi product ions are much less abundant as the carbon chain length and number of double bonds increase. The use of a mixture of D 0 /D 6 -acetone facilitates identification of these double bonds indicating product ions as shown for arachidonic acid. If oxygen is present in the solvent stream undergoing UV photoactivation, ozone cleavage ions are also observed without prior collisional activation. This reaction was used to determine the double bond positions in a 20:3 fatty acid that accumulated in phospholipids of RAW 264.7 cells cultured for 3 days.

  11. The Importance of Amoxicillin and Amoxicillin-Clavulanate Determinants in the Diagnosis of Immediate Allergic Reactions to β-Lactams.

    PubMed

    Confino-Cohen, Ronit; Rosman, Yossi; Lachover, Idit; Meir Shafrir, Keren; Goldberg, Arnon

    2016-01-01

    Immediate allergic reactions to β-lactam antibiotics are considered to be one of the most important drug hypersensitivities. A positive skin test (ST) with a combination of major and minor penicillin determinants is usually sufficient to recommend avoidance of the culprit drug, whereas a negative ST is usually followed by an oral challenge test (OCT). Recently, concern has been raised regarding the role of amoxicillin (AMX) ST in the diagnosis of AMX allergy. The aim of this study was to examine the additive value of AMX determinants in STs of patients with immediate hypersensitivity reactions to AMX or AMX-clavulanate (AMX-C). Patients with a history of immediate AMX or AMX-C allergy underwent an ST using a combination of penicilloyl-polylysine (PPL) and minor determinants as well as AMX. An ST with AMX-C was added when appropriate. Thirty-one patients were evaluated. Eight patients, all of them with a history of AMX allergy, had positive reactions only to the AMX component. Two patients with AMX-C allergy had a positive ST reaction only to the AMX-C component. Moreover, only 14 patients (13 with AMX and 1 with AMX-C allergy) had a positive reaction to PPL, whereas most patients (54.8%) had positive reactions to other determinants. One patient, who was positive for AMX, developed several urticarial lesions after the test. Skin testing with AMX and AMX-C is mandatory in patients with immediate allergy to these drugs. Failure to perform it may result in a false-negative ST jeopardizing these patients with anaphylactic reactions during a hazardous OCT. © 2016 S. Karger AG, Basel.

  12. False-positive LSD testing in urine samples from intensive care patients.

    PubMed

    Röhrich, J; Zörntlein, S; Lotz, J; Becker, J; Kern, T; Rittner, C

    1998-09-01

    Unexpected positive results for lysergic acid diethylamide (LSD) were found in urine samples from 12 patients in an intensive care unit in a routine screening using the CEDIA DAU assay. None of these test results could be confirmed by high-performance liquid chromatography analysis, but all samples contained the mucolytic drug ambroxol. Further studies demonstrated that ambroxol exhibits a significant cross-reactivity in the CEDIA DAU LSD assay. Therefore, positive LSD results obtained with the CEDIA DAU assay have to be critically evaluated, particularly during the cold season, when infections of the respiratory tract often result in more frequent use of mucolytic medications.

  13. Partial 'Seminole' Panorama (False Color)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This view from Spirit's panoramic camera is assembled from frames acquired on Martian days, or sols, 672 and 673 (Nov. 23 and 24, 2005) from the rover's position near an outcrop called 'Seminole.' The view is a southward-looking portion of a larger panorama still being completed. This is a false-color version to emphasize geological differences. It is a composite of images shot through three different filters, admitting light of wavelengths 750 nanometers, 530 nanometers and 430 nanometers.

  14. False-positive 18F-fluorodeoxyglucose positron emission tomography/computed tomography in a patient with metallic implants following chondrosarcoma resection.

    PubMed

    Zhou, P U; Tang, Jinliang; Zhang, Dong; Li, Guanghui

    2016-05-01

    Positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose ( 18 F-FDG) has been used for the staging and evaluation of recurrence in cancer patients. We herein report a false-positive result of 18 F-FDG PET/computed tomography (CT) scan in a patient following chondrosarcoma resection and metallic implanting. A 35-year-old male patient with chondrosarcoma of the left iliac bone underwent radical resection, metal brace implanting and radiotherapy. A high uptake of 18 F-FDG was observed in the metallic implants and adjacent tissue during PET/CT scanning in the 5th year of follow-up. Tissue biopsy and follow-up examination identified no tumor recurrence or infection at these sites, suggesting that the results of 18 F-FDG PET/CT must be interpreted with caution in cancer patients with metallic implants.

  15. Two-step glutamate dehydrogenase antigen real-time polymerase chain reaction assay for detection of toxigenic Clostridium difficile.

    PubMed

    Goldenberg, S D; Cliff, P R; Smith, S; Milner, M; French, G L

    2010-01-01

    Current diagnosis of Clostridium difficile infection (CDI) relies upon detection of toxins A/B in stool by enzyme immunoassay [EIA(A/B)]. This strategy is unsatisfactory because it has a low sensitivity resulting in significant false negatives. We investigated the performance of a two-step algorithm for diagnosis of CDI using detection of glutamate dehydrogenase (GDH). GDH-positive samples were tested for C. difficile toxin B gene (tcdB) by polymerase chain reaction (PCR). The performance of the two-step protocol was compared with toxin detection by the Meridian Premier EIA kit in 500 consecutive stool samples from patients with suspected CDI. The reference standard among samples that were positive by either EIA(A/B) or GDH testing was culture cytotoxin neutralisation (culture/CTN). Thirty-six (7%) of 500 samples were identified as true positives by culture/CTN. EIA(A/B) identified 14 of the positive specimens with 22 false negatives and two false positives. The two-step protocol identified 34 of the positive samples with two false positives and two false negatives. EIA(A/B) had a sensitivity of 39%, specificity of 99%, positive predictive value of 88% and negative predictive value of 95%. The two-step algorithm performed better, with corresponding values of 94%, 99%, 94% and 99% respectively. Screening for GDH before confirmation of positives by PCR is cheaper than screening all specimens by PCR and is an effective method for routine use. Current EIA(A/B) tests for CDI are of inadequate sensitivity and should be replaced; however, this may result in apparent changes in CDI rates that would need to be explained in national surveillance statistics. Copyright 2009 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.

  16. A Metric for Reducing False Positives in the Computer-Aided Detection of Breast Cancer from Dynamic Contrast-Enhanced Magnetic Resonance Imaging Based Screening Examinations of High-Risk Women.

    PubMed

    Levman, Jacob E D; Gallego-Ortiz, Cristina; Warner, Ellen; Causer, Petrina; Martel, Anne L

    2016-02-01

    Magnetic resonance imaging (MRI)-enabled cancer screening has been shown to be a highly sensitive method for the early detection of breast cancer. Computer-aided detection systems have the potential to improve the screening process by standardizing radiologists to a high level of diagnostic accuracy. This retrospective study was approved by the institutional review board of Sunnybrook Health Sciences Centre. This study compares the performance of a proposed method for computer-aided detection (based on the second-order spatial derivative of the relative signal intensity) with the signal enhancement ratio (SER) on MRI-based breast screening examinations. Comparison is performed using receiver operating characteristic (ROC) curve analysis as well as free-response receiver operating characteristic (FROC) curve analysis. A modified computer-aided detection system combining the proposed approach with the SER method is also presented. The proposed method provides improvements in the rates of false positive markings over the SER method in the detection of breast cancer (as assessed by FROC analysis). The modified computer-aided detection system that incorporates both the proposed method and the SER method yields ROC results equal to that produced by SER while simultaneously providing improvements over the SER method in terms of false positives per noncancerous exam. The proposed method for identifying malignancies outperforms the SER method in terms of false positives on a challenging dataset containing many small lesions and may play a useful role in breast cancer screening by MRI as part of a computer-aided detection system.

  17. Sadder and less accurate? False memory for negative material in depression.

    PubMed

    Joormann, Jutta; Teachman, Bethany A; Gotlib, Ian H

    2009-05-01

    Previous research has demonstrated that induced sad mood is associated with increased accuracy of recall in certain memory tasks; the effects of clinical depression, however, are likely to be quite different. The authors used the Deese-Roediger-McDermott paradigm to examine the impact of clinical depression on erroneous recall of neutral and/or emotional stimuli. Specifically, they presented Deese-Roediger-McDermott lists that were highly associated with negative, neutral, or positive lures and compared participants diagnosed with major depressive disorder and nondepressed control participants on the accuracy of their recall of presented material and their false recall of never-presented lures. Compared with control participants, major depressive disorder participants recalled fewer words that had been previously presented but were more likely to falsely recall negative lures; there were no differences between major depressive disorder and control participants in false recall of positive or neutral lures. These findings indicate that depression is associated with false memories of negative material.

  18. False discovery rates in spectral identification.

    PubMed

    Jeong, Kyowon; Kim, Sangtae; Bandeira, Nuno

    2012-01-01

    Automated database search engines are one of the fundamental engines of high-throughput proteomics enabling daily identifications of hundreds of thousands of peptides and proteins from tandem mass (MS/MS) spectrometry data. Nevertheless, this automation also makes it humanly impossible to manually validate the vast lists of resulting identifications from such high-throughput searches. This challenge is usually addressed by using a Target-Decoy Approach (TDA) to impose an empirical False Discovery Rate (FDR) at a pre-determined threshold x% with the expectation that at most x% of the returned identifications would be false positives. But despite the fundamental importance of FDR estimates in ensuring the utility of large lists of identifications, there is surprisingly little consensus on exactly how TDA should be applied to minimize the chances of biased FDR estimates. In fact, since less rigorous TDA/FDR estimates tend to result in more identifications (at higher 'true' FDR), there is often little incentive to enforce strict TDA/FDR procedures in studies where the major metric of success is the size of the list of identifications and there are no follow up studies imposing hard cost constraints on the number of reported false positives. Here we address the problem of the accuracy of TDA estimates of empirical FDR. Using MS/MS spectra from samples where we were able to define a factual FDR estimator of 'true' FDR we evaluate several popular variants of the TDA procedure in a variety of database search contexts. We show that the fraction of false identifications can sometimes be over 10× higher than reported and may be unavoidably high for certain types of searches. In addition, we further report that the two-pass search strategy seems the most promising database search strategy. While unavoidably constrained by the particulars of any specific evaluation dataset, our observations support a series of recommendations towards maximizing the number of resulting

  19. Public health consequences of a false-positive laboratory test result for Brucella--Florida, Georgia, and Michigan, 2005.

    PubMed

    2008-06-06

    Human brucellosis, a nationally notifiable disease, is uncommon in the United States. Most human cases have occurred in returned travelers or immigrants from regions where brucellosis is endemic, or were acquired domestically from eating illegally imported, unpasteurized fresh cheeses. In January 2005, a woman aged 35 years who lived in Nassau County, Florida, received a diagnosis of brucellosis, based on results of a Brucella immunoglobulin M (IgM) enzyme immunoassay (EIA) performed in a commercial laboratory using analyte specific reagents (ASRs); this diagnosis prompted an investigation of dairy products in two other states. Subsequent confirmatory antibody testing by Brucella microagglutination test (BMAT) performed at CDC on the patient's serum was negative. The case did not meet the CDC/Council of State and Territorial Epidemiologists' (CSTE) definition for a probable or confirmed brucellosis case, and the initial EIA result was determined to be a false positive. This report summarizes the case history, laboratory findings, and public health investigations. CDC recommends that Brucella serology testing only be performed using tests cleared or approved by the Food and Drug Administration (FDA) or validated under the Clinical Laboratory Improvement Amendments (CLIA) and shown to reliably detect the presence of Brucella infection. Results from these tests should be considered supportive evidence for recent infection only and interpreted in the context of a clinically compatible illness and exposure history. EIA is not considered a confirmatory Brucella antibody test; positive screening test results should be confirmed by Brucella-specific agglutination (i.e., BMAT or standard tube agglutination test) methods.

  20. Clinical Characteristics and Outcomes of Hematologic Malignancy Patients With Positive Clostridium difficile Toxin Immunoassay Versus Polymerase Chain Reaction Test Results.

    PubMed

    Ziegler, Matthew; Landsburg, Daniel; Pegues, David; Alby, Kevin; Gilmar, Cheryl; Bink, Kristen; Gorman, Theresa; Moore, Amy; Bonhomme, Brittaney; Omorogbe, Jacqueline; Tango, Dana; Tolomeo, Pam; Han, Jennifer H

    2018-04-25

    In a cohort of inpatients with hematologic malignancy and positive enzyme immunoassay (EIA) or polymerase chain reaction (PCR) Clostridium difficile tests, we found that clinical characteristics and outcomes were similar between these groups. The method of testing is unlikely to predict infection in this population, and PCR-positive results should be treated with concern.Infect Control Hosp Epidemiol 2018;1-4.

  1. Publication bias and the canonization of false facts.

    PubMed

    Nissen, Silas Boye; Magidson, Tali; Gross, Kevin; Bergstrom, Carl T

    2016-12-20

    Science is facing a "replication crisis" in which many experimental findings cannot be replicated and are likely to be false. Does this imply that many scientific facts are false as well? To find out, we explore the process by which a claim becomes fact. We model the community's confidence in a claim as a Markov process with successive published results shifting the degree of belief. Publication bias in favor of positive findings influences the distribution of published results. We find that unless a sufficient fraction of negative results are published, false claims frequently can become canonized as fact. Data-dredging, p-hacking, and similar behaviors exacerbate the problem. Should negative results become easier to publish as a claim approaches acceptance as a fact, however, true and false claims would be more readily distinguished. To the degree that the model reflects the real world, there may be serious concerns about the validity of purported facts in some disciplines.

  2. Cross-reactions among hair dye allergens.

    PubMed

    Basketter, David A; English, John

    2009-01-01

    p-Phenylenediamine (PPD) is an important hair dye allergen, but there remains a reasonable suspicion that other hair dye chemicals may also be responsible for a proportion of the clinical burden of hair dye allergy. To assess to what extent presently assessed additional patch test agents contribute to the diagnosis of non-PPD hair dye allergy. A retrospective analysis was conducted of patch test results with hair dye allergens, focusing on the extent to which patients who were positive for allergic reactions to other hair dye allergens also had a concomitant positive reaction to PPD. For the hair dye allergens other than p-toluenediamine (PTD), reactions in the absence of a concomitant positive reaction to PPD were very rare. Positive reactors to PTD were also positive for reactions to PPD in 5 of every 6 cases. Pyrogallol positives often occurred in the absence of a PPD positive, but were never judged to be of clinical relevance. Hair dye chemicals other than PPD may be of importance, but the presently tested materials, with the possible exception of PTD, are normally positive only when a PPD-positive reaction is also present, suggesting that their use in patch testing in hair dye allergy is likely to be of limited value.

  3. Bites of the European pigeon tick (Argas reflexus): Risk of IgE-mediated sensitizations and anaphylactic reactions.

    PubMed

    Kleine-Tebbe, Jörg; Heinatz, Anja; Gräser, Inken; Dautel, Hans; Hansen, Gitte Nordskov; Kespohl, Sabine; Rihs, Hans-Peter; Raulf-Heimsoth, Monika; Vater, Günther; Rytter, Manfred; Haustein, Uwe-Fritjof

    2006-01-01

    Local and systemic reactions can occur after bites of Argas reflexus (Argas), a soft tick parasitizing pigeons. Risk assessment of IgE-mediated sensitizations and systemic reactions after Argas bites. Case histories, skin prick tests (SPTs) with a whole-body extract of Argas containing major allergen Arg r 1, and common inhalants and specific IgE measurements were obtained from 148 subjects who had had Argas bites and 20 volunteers as a control group. Systemic reactions (urticaria, angioedema, dyspnea, cardiovascular dysregulation, unconsciousness) were reported in 12 of 148 (8%); 146 of 148 (99%) had local reactions. Atopy was found in 37 of 146 (25%) with local reactions and 3 of 12 (25%) with systemic reactions. SPT to Argas was positive in 24 of 148 (16%) with a high proportion of atopics 10 of 24 (42%); specific IgE to Argas was detectable in 12 of 135 (8% of 148) with moderate concordance to systemic reactions. No positive SPT or specific IgE results to Argas were obtained in the control group. Immunoblotting of 23 sera revealed an IgE-binding protein in 19 of 23 sera (82%) at 22 kd, indicating a major allergen of Argas. Severe anaphylactic reactions were infrequently (approximately 8%) found after bites of the soft tick Argas reflexus. Atopy is a risk factor for skin sensitizations to Argas, but not for systemic reactions after bites by Argas. Using a whole-body extract of Argas, diagnosis through SPT and specific IgE is hampered by false-negative and irrelevant positive results, particularly in atopy.

  4. Automated detection of retinal nerve fiber layer defects on fundus images: false positive reduction based on vessel likelihood

    NASA Astrophysics Data System (ADS)

    Muramatsu, Chisako; Ishida, Kyoko; Sawada, Akira; Hatanaka, Yuji; Yamamoto, Tetsuya; Fujita, Hiroshi

    2016-03-01

    Early detection of glaucoma is important to slow down or cease progression of the disease and for preventing total blindness. We have previously proposed an automated scheme for detection of retinal nerve fiber layer defect (NFLD), which is one of the early signs of glaucoma observed on retinal fundus images. In this study, a new multi-step detection scheme was included to improve detection of subtle and narrow NFLDs. In addition, new features were added to distinguish between NFLDs and blood vessels, which are frequent sites of false positives (FPs). The result was evaluated with a new test dataset consisted of 261 cases, including 130 cases with NFLDs. Using the proposed method, the initial detection rate was improved from 82% to 98%. At the sensitivity of 80%, the number of FPs per image was reduced from 4.25 to 1.36. The result indicates the potential usefulness of the proposed method for early detection of glaucoma.

  5. Concordant Chemical Reaction Networks and the Species-Reaction Graph

    PubMed Central

    Shinar, Guy; Feinberg, Martin

    2015-01-01

    In a recent paper it was shown that, for chemical reaction networks possessing a subtle structural property called concordance, dynamical behavior of a very circumscribed (and largely stable) kind is enforced, so long as the kinetics lies within the very broad and natural weakly monotonic class. In particular, multiple equilibria are precluded, as are degenerate positive equilibria. Moreover, under certain circumstances, also related to concordance, all real eigenvalues associated with a positive equilibrium are negative. Although concordance of a reaction network can be decided by readily available computational means, we show here that, when a nondegenerate network’s Species-Reaction Graph satisfies certain mild conditions, concordance and its dynamical consequences are ensured. These conditions are weaker than earlier ones invoked to establish kinetic system injectivity, which, in turn, is just one ramification of network concordance. Because the Species-Reaction Graph resembles pathway depictions often drawn by biochemists, results here expand the possibility of inferring significant dynamical information directly from standard biochemical reaction diagrams. PMID:22940368

  6. GammadeltaT cells positively regulate contact sensitivity (CS) reaction via modulation of INF-gamma, IL-12 and TNF-alpha production.

    PubMed

    Strzepa, Anna; Majewska-Szczepanik, Monika; Szczepanik, Marian

    2013-01-01

    The gammadeltaT cells were identified as positive as well as negative regulators of immune responses. They take part in pathogen clearance, modulation of innate and adaptive immunity as well as in healing and tissue maintenance. The course of many pathological conditions such as collagen induced arthritis (CIA), experimental autoimmune encephalomyelitis (EAE) and airway hyperresponsiveness is positively regulated by gammadeltaT cells. It was shown previously that contact sensitivity (CS), an example of antigen-specific cell-mediated immune response, is also positively regulated by gammadeltaT cells. The current work confirmed the regulatory function of gammadeltaT cells in CS response as their depletion with anti-TCRdelta monoclonal antibody and complement significantly decreased adoptive transfer of the CS reaction. In vitro study showed that removal of gammadeltaT cells with magnetic beads significantly decreased the production of the proinflammatory cytokines IFN-gamma, IL-12 and TNF-alpha. Reconstitution of gammadeltaT-depleted cells with gammadeltaT-enriched cells restored cytokine production, proving the reversibility of the investigated process. In summary, gammadeltaT cells positively regulate the CS reaction via modulation of proinflammatory cytokine production.

  7. False-positive 18F-fluorodeoxyglucose positron emission tomography/computed tomography in a patient with metallic implants following chondrosarcoma resection

    PubMed Central

    ZHOU, PU; TANG, JINLIANG; ZHANG, DONG; LI, GUANGHUI

    2016-01-01

    Positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose (18F-FDG) has been used for the staging and evaluation of recurrence in cancer patients. We herein report a false-positive result of 18F-FDG PET/computed tomography (CT) scan in a patient following chondrosarcoma resection and metallic implanting. A 35-year-old male patient with chondrosarcoma of the left iliac bone underwent radical resection, metal brace implanting and radiotherapy. A high uptake of 18F-FDG was observed in the metallic implants and adjacent tissue during PET/CT scanning in the 5th year of follow-up. Tissue biopsy and follow-up examination identified no tumor recurrence or infection at these sites, suggesting that the results of 18F-FDG PET/CT must be interpreted with caution in cancer patients with metallic implants. PMID:27123290

  8. False recollection of emotional pictures in Alzheimer's disease.

    PubMed

    Gallo, David A; Foster, Katherine T; Wong, Jessica T; Bennett, David A

    2010-10-01

    Alzheimer's Disease (AD) can reduce the effects of emotional content on memory for studied pictures, but less is known about false memory. In healthy adults, emotionally arousing pictures can be more susceptible to false memory effects than neutral pictures, potentially because emotional pictures share conceptual similarities that cause memory confusions. We investigated these effects in AD patients and healthy controls. Participants studied pictures and their verbal labels, and then picture recollection was tested using verbal labels as retrieval cues. Some of the test labels had been associated with a picture at study, whereas other had not. On this picture recollection test, we found that both AD patients and controls incorrectly endorsed some of the test labels that had not been studied with pictures. These errors were associated with medium to high levels of confidence, indicating some degree of false recollection. Critically, these false recollection judgments were greater for emotional compared to neutral items, especially for positively valenced items, in both AD patients and controls. Dysfunction of the amygdala and hippocampus in early AD may impair recollection, but AD did not disrupt the effect of emotion on false recollection judgments. Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. A note on the false discovery rate of novel peptides in proteogenomics.

    PubMed

    Zhang, Kun; Fu, Yan; Zeng, Wen-Feng; He, Kun; Chi, Hao; Liu, Chao; Li, Yan-Chang; Gao, Yuan; Xu, Ping; He, Si-Min

    2015-10-15

    Proteogenomics has been well accepted as a tool to discover novel genes. In most conventional proteogenomic studies, a global false discovery rate is used to filter out false positives for identifying credible novel peptides. However, it has been found that the actual level of false positives in novel peptides is often out of control and behaves differently for different genomes. To quantitatively model this problem, we theoretically analyze the subgroup false discovery rates of annotated and novel peptides. Our analysis shows that the annotation completeness ratio of a genome is the dominant factor influencing the subgroup FDR of novel peptides. Experimental results on two real datasets of Escherichia coli and Mycobacterium tuberculosis support our conjecture. yfu@amss.ac.cn or xupingghy@gmail.com or smhe@ict.ac.cn Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press.

  10. Prevalence of Adverse Drug Reactions to Highly Active Antiretroviral Therapy (HAART) among HIV Positive Patients in Imam Khomeini Hospital of Tehran, Iran.

    PubMed

    Koochak, Hamid E; Babaii, Azita; Pourdast, Alia; Golrokhy, Raheleh; Rasoolinejad, Mehrnaz; Khodaei, Sepideh; Moghadam, Saeed R J; Taheri, Reza R; Seyed Alinaghi, Seyed Ahmad

    2017-01-01

    The present study assessed the prevalence of adverse drug reactions (ADRs) among HIV positive patients taking antiretroviral therapy referred to Imam Khomeini Hospital in Tehran, Iran. This is a cross sectional study regarding side effects of Highly Active Antiretroviral Therapy (HAART) in HIV positive patients referred to Voluntary Counseling and Testing (VCT) center in Imam Khomeini Hospital of Tehran, Iran during a period of the year 2009 to 2010. Two hundred patients under antiretroviral treatment evaluated for the side effects of drug based on available records, face to face interviews and written lab data. Data was collected from a sample of 200 HIV positive patients (72% male). Injection drug use was the most common route of HIV transmission. Co-Infections with Hepatitis C virus (HCV) found in the majority of patients (60.5%). Tuberculosis was the most prevalent opportunistic infection. One hundred eighty eight (94%) patients experienced at least one adverse drug reaction. The most frequent clinical and paraclinical findings were skin rash (28%) and abnormal liver function tests (36%). Given the high prevalence of adverse drug reactions among HIV positive patients taking antiretroviral therapy (ART) in this study, clinicians should be aware of ADRs at the initiation of ART as complications can affect patients' adherence to the therapy. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  11. False memory and the associative network of happiness.

    PubMed

    Koo, Minkyung; Oishi, Shigehiro

    2009-02-01

    This research examines the relationship between individuals' levels of life satisfaction and their associative networks of happiness. Study 1 measured European Americans' degree of false memory of happiness using the Deese-Roediger-McDermott paradigm. Scores on the Satisfaction With Life Scale predicted the likelihood of false memory of happiness but not of other lure words such as sleep . In Study 2, European American participants completed an association-judgment task in which they judged the extent to which happiness and each of 15 positive emotion terms were associated with each other. Consistent with Study 1's findings, chronically satisfied individuals exhibited stronger associations between happiness and other positive emotion terms than did unsatisfied individuals. However, Koreans and Asian Americans did not exhibit such a pattern regarding their chronic level of life satisfaction (Study 3). In combination, results suggest that there are important individual and cultural differences in the cognitive structure and associative network of happiness.

  12. Do 15-month-old infants understand false beliefs?

    PubMed

    Onishi, Kristine H; Baillargeon, Renée

    2005-04-08

    For more than two decades, researchers have argued that young children do not understand mental states such as beliefs. Part of the evidence for this claim comes from preschoolers' failure at verbal tasks that require the understanding that others may hold false beliefs. Here, we used a novel nonverbal task to examine 15-month-old infants' ability to predict an actor's behavior on the basis of her true or false belief about a toy's hiding place. Results were positive, supporting the view that, from a young age, children appeal to mental states--goals, perceptions, and beliefs--to explain the behavior of others.

  13. Modeling Kepler Transit Light Curves as False Positives: Rejection of Blend Scenarios for Kepler-9, and Validation of Kepler-9 d, a Super-Earth-Size Planet in a Multiple System

    NASA Technical Reports Server (NTRS)

    Torres, Guillermo; Fressin, Francois; Batalha, Natalie M.; Borucki, William J.; Brown, Timothy M.; Bryson, Stephen T.; Buchhave, Lars A.; Charbonneau, David; Ciardi, David R.; Dunham, Edward W.; hide

    2011-01-01

    Light curves from the Kepler Mission contain valuable information on the nature of the phenomena producing the transit-like signals. To assist in exploring the possibility that they are due to an astrophysical false positive we describe a procedure (BLENDER) to model the photometry in terms of a blend rather than a planet orbiting a star. A blend may consist of a background or foreground eclipsing binary (or star-planet pair) whose eclipses are attenuated by the light of the candidate and possibly other stars within the photometric aperture. We apply BLENDER to the case of Kepler-9 (KIC 3323887), a target harboring two previously confirmed Saturn-size planets (Kepler-9 b and Kepler-9 c) showing transit timing variations, and an additional shallower signal with a 1.59 day period suggesting the presence of a super-Earth-size planet. Using BLENDER together with constraints from other follow-up observations we are able to rule out all blends for the two deeper signals and provide independent validation of their planetary nature. For the shallower signal, we rule out a large fraction of the false positives that might mimic the transits. The false alarm rate for remaining blends depends in part (and inversely) on the unknown frequency of small-size planets. Based on several realistic estimates of this frequency, we conclude with very high confidence that this small signal is due to a super-Earth-size planet (Kepler-9 d) in a multiple system, rather than a false positive. The radius is determined to be 1.64(exp)(sub-14),R, and current spectroscopic observations are as yet insufficient to establish its mass.

  14. False memories and memory confidence in borderline patients.

    PubMed

    Schilling, Lisa; Wingenfeld, Katja; Spitzer, Carsten; Nagel, Matthias; Moritz, Steffen

    2013-12-01

    Mixed results have been obtained regarding memory in patients with borderline personality disorder (BPD). Prior reports and anecdotal evidence suggests that patients with BPD are prone to false memories but this assumption has to been put to firm empirical test, yet. Memory accuracy and confidence was assessed in 20 BPD patients and 22 healthy controls using a visual variant of the false memory (Deese-Roediger-McDermott) paradigm which involved a negative and a positive-valenced picture. Groups did not differ regarding veridical item recognition. Importantly, patients did not display more false memories than controls. At trend level, borderline patients rated more items as new with high confidence compared to healthy controls. The results tentatively suggest that borderline patients show uncompromised visual memory functions and display no increased susceptibility for distorted memories. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. [Pitfalls in the histopathological diagnostics of endometrial carcinoma and its precursors : Clinically relevant differential diagnoses, avoidance of false positive diagnoses].

    PubMed

    Kommoss, F; Lax, S F

    2016-11-01

    Making an incorrect histopathological diagnosis of an endometrial lesion may lead to unwanted loss of fertility and therapy-associated morbidity; therefore, endometrial carcinomas need to be correctly typed and differentiated from hyperplastic precursors, benign lesions and artifacts. Typical diagnostic pitfalls are described in this article. Misdiagnosing endometrial lesions can be avoided by paying thorough attention to gross as well as microscopic features and by taking crucial differential diagnoses into consideration. These are, in particular, well-differentiated endometrioid adenocarcinoma of the endometrium versus atypical endometrial hyperplasia, myoinvasive endometrioid adenocarcinoma versus atypical polypoid adenomyoma and endometrioid carcinoma versus serous carcinoma of the endometrium with a predominantly glandular pattern. It is also important to consider the possibility of a false positive diagnosis of atypical endometrial hyperplasia or carcinoma in cases of biopsy-induced artifacts.

  16. Publication bias and the canonization of false facts

    PubMed Central

    Nissen, Silas Boye; Magidson, Tali; Gross, Kevin; Bergstrom, Carl T

    2016-01-01

    Science is facing a “replication crisis” in which many experimental findings cannot be replicated and are likely to be false. Does this imply that many scientific facts are false as well? To find out, we explore the process by which a claim becomes fact. We model the community’s confidence in a claim as a Markov process with successive published results shifting the degree of belief. Publication bias in favor of positive findings influences the distribution of published results. We find that unless a sufficient fraction of negative results are published, false claims frequently can become canonized as fact. Data-dredging, p-hacking, and similar behaviors exacerbate the problem. Should negative results become easier to publish as a claim approaches acceptance as a fact, however, true and false claims would be more readily distinguished. To the degree that the model reflects the real world, there may be serious concerns about the validity of purported facts in some disciplines. DOI: http://dx.doi.org/10.7554/eLife.21451.001 PMID:27995896

  17. Significance of immunoglobulin G4 (IgG4)-positive cells in extrahepatic cholangiocarcinoma: molecular mechanism of IgG4 reaction in cancer tissue.

    PubMed

    Harada, Kenichi; Shimoda, Shinji; Kimura, Yasushi; Sato, Yasunori; Ikeda, Hiroko; Igarashi, Saya; Ren, Xiang-Shan; Sato, Hirohide; Nakanuma, Yasuni

    2012-07-01

    IgG4 reactions consisting of marked infiltration by immunoglobulin G4 (IgG4)-positive plasma cells in affected organs is found in cancer patients as well as patients with IgG4-related diseases. Notably, extrahepatic cholangiocarcinomas accompanying marked IgG4 reactions clinicopathologically mimic IgG4-related sclerosing cholangitis. The regulatory cytokine interleukin (IL)-10 is thought to induce the differentiation of IgG4-positive cells. In this study, to clarify the mechanism of the IgG4 reaction in extrahepatic cholangiocarcinoma, we investigated nonprofessional antigen-presenting cells (APCs) generating IL-10-producing regulatory T cells (anergy T cells) and Foxp3-positive regulatory cells producing IL-10. Immunohistochemistry targeting IgG4, HLA-DR, CD80, CD86, and Foxp3 was performed using 54 cholangiocarcinoma specimens from 24 patients with gallbladder cancer, 22 patients with common bile duct cancer, and eight patients with cancer of the Papilla of Vater. Moreover, a molecular analysis of Foxp3 and IL-10 was performed using a cultured human cholangiocarcinoma cell line. Consequently, 43% of the cholangiocarcinomas were found to be abundant in IgG4. Those expressing HLA-DR but lacking costimulatory molecules (CD80 and CD86) and those expressing Foxp3 detected by an antibody recognizing the N terminus accounted for 54% and 39% of cases, respectively. Moreover, the number of IgG4-positive cells was larger in these cases than in other groups. In cultured cells, the presence of a splicing variant of Foxp3 messenger RNA and the expression of IL-10 were demonstrated. Extrahepatic cholangiocarcinoma is often accompanied by significant infiltration of IgG4-positive cells. Cholangiocarcinoma cells could play the role of nonprofessional APCs and Foxp3-positive regulatory cells, inducing IgG4 reactions via the production of IL-10 indirectly and directly, respectively. Copyright © 2012 American Association for the Study of Liver Diseases.

  18. False Belief Performance of Children Adopted Internationally.

    PubMed

    Hwa-Froelich, Deborah A; Matsuo, Hisako; Jacobs, Kristal

    2017-02-01

    The purpose of this study was to explore relationships among adoption, individual, and family variables on false belief performance of children adopted internationally (CAI). Using a quasiexperimental design, thirty-five 4-year-old children adopted from Asian and Eastern European countries before age 2 years were compared with a U.S. group of 33 nonadopted 4-year-old children on a standardized English-language measure, 3 false belief tasks, and a go/no-go inhibition measure. The adopted group differed significantly from the U.S. nonadopted group in expressive language and false belief performance. For the adopted group, inhibition measures were significantly correlated with core language scores. Core language scores and number of older siblings predicted false belief performance. Similar to children who are not adopted, language competence and living with older siblings positively influenced social understanding in CAI. Because CAI experience interrupted language acquisition and live with fewer older siblings, they are at risk of having weaker language competence and social understanding in their adopted language. When working with CAI, practitioners should assess social communication, language competence, and inhibition skills. They should assist adoptive families in providing socially mentored opportunities for their children to observe and interact with older children.

  19. Confabulation versus experimentally induced false memories in Korsakoff patients.

    PubMed

    Van Damme, Ilse; d'Ydewalle, Géry

    2010-09-01

    The present study focuses on both the clinical symptom of confabulation and experimentally induced false memories in patients suffering from Korsakoff's syndrome. Despite the vast amount of case studies of confabulating patients and studies investigating false memories in the Deese-Roediger-McDermott (DRM) paradigm, the nature of Korsakoff patients' confabulatory behaviour and its association with DRM false memories have been rarely examined. Hence, the first aim of the present study was to evaluate confabulatory responses in a large sample of chronic Korsakoff patients and matched controls by means of the Dalla Barba Confabulation Battery. Second, the association between (provoked) confabulation and the patients' DRM false recognition performance was investigated. Korsakoff patients mainly confabulated in response to questions about episodic memory and questions to which the answer was unknown. A positive association was obtained between confabulation and the tendency to accept unstudied distractor words as being old in the DRM paradigm. On the other hand, there was a negative association between confabulation and false recognition of critical lures. The latter could be attributed to the importance of strategic retrieval at delayed memory testing.

  20. Desensitization in delayed drug hypersensitivity reactions -- an EAACI position paper of the Drug Allergy Interest Group.

    PubMed

    Scherer, K; Brockow, K; Aberer, W; Gooi, J H C; Demoly, P; Romano, A; Schnyder, B; Whitaker, P; Cernadas, J S R; Bircher, A J

    2013-07-01

    Drug hypersensitivity may deprive patients of drug therapy, and occasionally no effective alternative treatment is available. Successful desensitization has been well documented in delayed drug hypersensitivity reactions. In certain situations, such as sulfonamide hypersensitivity in HIV-positive patients or hypersensitivity to antibiotics in patients with cystic fibrosis, published success rates reach 80%, and this procedure appears helpful for the patient management. A state of clinical tolerance may be achieved by the administration of increasing doses of the previously offending drug. However, in most cases, a pre-existent sensitization has not been proven by positive skin tests. Successful re-administration may have occurred in nonsensitized patients. A better understanding of the underlying mechanisms of desensitization is needed. Currently, desensitization in delayed hypersensitivity reactions is restricted to mild, uncomplicated exanthems and fixed drug eruptions. The published success rates vary depending on clinical manifestations, drugs, and applied protocols. Slower protocols tend to be more effective than rush protocols; however, underreporting of unsuccessful procedures is very probable. The decision to desensitize a patient must always be made on an individual basis, balancing risks and benefits. This paper reviews the literature and presents the expert experience of the Drug Hypersensitivity Interest Group of the European Academy of Allergy and Clinical Immunology. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. A critical reappraisal of false negative sentinel lymph node biopsy in melanoma.

    PubMed

    Manca, G; Romanini, A; Rubello, D; Mazzarri, S; Boni, G; Chiacchio, S; Tredici, M; Duce, V; Tardelli, E; Volterrani, D; Mariani, G

    2014-06-01

    Lymphatic mapping and sentinel lymph node biopsy (SLNB) have completely changed the clinical management of cutaneous melanoma. This procedure has been accepted worldwide as a recognized method for nodal staging. SLNB is able to accurately determine nodal basin status, providing the most useful prognostic information. However, SLNB is not a perfect diagnostic test. Several large-scale studies have reported a relatively high false-negative rate (5.6-21%), correctly defined as the proportion of false-negative results with respect to the total number of "actual" positive lymph nodes. The main purpose of this review is to address the technical issues that nuclear physicians, surgeons, and pathologists should carefully consider to improve the accuracy of SLNB by minimizing its false-negative rate. In particular, SPECT/CT imaging has demonstrated to be able to identify a greater number of sentinel lymph nodes (SLNs) than those found by planar lymphoscintigraphy. Furthermore, a unique definition in the international guidelines is missing for the operational identification of SLNs, which may be partly responsible for this relatively high false-negative rate of SLNB. Therefore, it is recommended for the scientific community to agree on the radioactive counting rate threshold so that the surgeon can be better radioguided to detect all the lymph nodes which are most likely to harbor metastases. Another possible source of error may be linked to the examination of the harvested SLNs by conventional histopathological methods. A more careful and extensive SLN analysis (e.g. molecular analysis by RT-PCR) is able to find more positive nodes, so that the false-negative rate is reduced. Older age at diagnosis, deeper lesions, histologic ulceration, head-neck anatomical location of primary lesions are the clinical factors associated with false-negative SLNBs in melanoma patients. There is still much controversy about the clinical significance of a false-negative SLNB on the prognosis

  2. Emotion and false memory: How goal-irrelevance can be relevant for what people remember.

    PubMed

    Van Damme, Ilse; Kaplan, Robin L; Levine, Linda J; Loftus, Elizabeth F

    2017-02-01

    Elaborating on misleading information concerning emotional events can lead people to form false memories. The present experiment compared participants' susceptibility to false memories when they elaborated on information associated with positive versus negative emotion and pregoal versus postgoal emotion. Pregoal emotion reflects appraisals that goal attainment or failure is anticipated but has not yet occurred (e.g., hope and fear). Postgoal emotion reflects appraisals that goal attainment or failure has already occurred (e.g., happiness and devastation). Participants watched a slideshow depicting an interaction between a couple and were asked to empathise with the protagonist's feelings of hope (positive pregoal), happiness (positive postgoal), fear (negative pregoal), or devastation (negative postgoal); in control conditions, no emotion was mentioned. Participants were then asked to reflect on details of the interaction that had occurred (true) or had not occurred (false), and that were relevant or irrelevant to the protagonist's goal. Irrespective of emotional valence, participants in the pregoal conditions were more susceptible to false memories concerning goal-irrelevant details than were participants in the other conditions. These findings support the view that pregoal emotions narrow attention to information relevant to goal pursuit, increasing susceptibility to false memories for irrelevant information.

  3. Do 15-Month-Old Infants Understand False Beliefs?

    PubMed Central

    Onishi, Kristine H.; Baillargeon, Renée

    2012-01-01

    For more than two decades, researchers have argued that young children do not understand mental states such as beliefs. Part of the evidence for this claim comes from preschoolers’ failure at verbal tasks that require the understanding that others may hold false beliefs. Here, we used a novel nonverbal task to examine 15-month-old infants’ ability to predict an actor’s behavior on the basis of her true or false belief about a toy’s hiding place. Results were positive, supporting the view that, from a young age, children appeal to mental states—goals, perceptions, and beliefs—to explain the behavior of others. PMID:15821091

  4. A novel duplex real time quantitative reverse transcription polymerase chain reaction for rubella virus with armored RNA as a noncompetitive internal positive control.

    PubMed

    Zhao, Lihong; Li, Ruiying; Liu, Aihua; Zhao, Shuping

    2015-07-01

    The objective of this study was to build and apply a duplex real time quantitative reverse transcription-polymerase chain reaction (RT-PCR) for rubella virus. Firstly, a 60-bp-long armored RV RNA was constructed in the laboratory. Secondly, a duplex real time RT-PCR assay was established. Thirdly, the 60-bp-long armored RV RNA was used as an internal positive control (IPC) for the duplex real time RT-PCR. And finally the duplex real time RT-PCR assay was applied to detect RV RNA in clinical specimens. The in-house assay has a high amplification efficiency (0.99), a high analytical sensitivity (200 copies/mL), and a good reproducibility. The diagnostic specificity and sensitivity of the in-house assay were both 100%, due to the monitoring of the armored RV RNA IPC. Therefore, the in-house duplex real time quantitative RT-PCR assay is a specific, sensitive, reproducible and accurate assay for quantitation of RV RNA in clinical specimens. And noncompetitive armored RV RNA IPC can monitor RT-PCR inhibition and prevent false-negative and inaccurate results in the real time detection system. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Heat treatment and false-positive heartworm antigen testing in ex vivo parasites and dogs naturally infected by Dirofilaria repens and Angiostrongylus vasorum.

    PubMed

    Venco, Luigi; Manzocchi, Simone; Genchi, Marco; Kramer, Laura H

    2017-11-09

    Heartworm antigen testing is considered sensitive and specific. Currently available tests are reported as detecting a glycoprotein found predominantly in the reproductive tract of the female worm and can reach specificity close to 100%. Main concerns regard sensitivity in the case of light infections, the presence of immature females or cases of all-male infections. Research and development have been aimed at increasing sensitivity. Recently, heat treatment of serum prior to antigen testing has been shown to result in an increase in positive antigen test results, presumably due to disruption of natural antigen-antibody complexes. Cross-reactions in dogs with both natural and experimental infections with Angiostrongylus vasorum and Spirocerca lupi have been reported, but cross-reactions with other helminths have not been extensively studied. In order to evaluate potential cross-reactivity with other canine and feline parasites, two studies were performed. Study 1: Live adults of Dirofilaria immitis, Dirofilaria repens, Toxocara canis, Toxocara cati, Dipylidium caninum, Taenia taeniaeformis and Mesocestoides spp. larvae were washed and incubated in tubes with saline solution. All worms were alive at the time of removal from the saline. Saline solutions containing excretory/secretory antigens were then tested for heartworm with six different, commercially available antigen tests. All results were evaluated blind by three of the authors. Study 2: Sera from dogs with natural infections by A. vasorum or D. repens, living in areas free of heartworm disease, were tested with the same tests before and after heat treatment (103 °C for 10 min). Results suggest that antigens detected by currently available tests are not specific for D. immitis. They may give positive results through detection of different parasites' antigens that are normally not released into the bloodstream or released in a low amount and/or bound to antibodies. Tests may even detect antigens released by

  6. Investigating Initial Disclosures and Reactions to Unexpected, Positive HPV Diagnosis.

    PubMed

    Smith, Rachel A; Hernandez, Rachael; Catona, Danielle

    2014-07-01

    Initial disclosures of health conditions are critical communication moments. Existing research focuses on disclosers; integrating confidants into studies of initial disclosures is needed. Guided by the disclosure decision-making model (DD-MM; Greene, 2009), this study examined what diagnosed persons and confidants may say when faced with unexpected test results and unexpected disclosures, respectively. Participants ( N = 151) recorded an audio-visual message for another person, after imagining that they or the other person had just received unexpected, positive HPV test results. The qualitative analysis revealed four themes: (1) impression management and social distance, (2) invisible symptoms and advice regarding future disclosures, (3) expressing and acknowledging emotional reactions, and (4) misunderstandings and lacking knowledge about HPV. These findings suggested that DD-MM may be a relevant framework for understanding not only when disclosers share, but what disclosers and confidants say in early conversations about new diagnoses. While disclosers' and confidants' messages showed marked similarities, important differences appeared. For example, confidants focused on assuaging disclosers' fear about the consequences, whereas disclosers expressed distress related to their uncertainty about the prognosis of an HPV infection and how to prepare for next steps. The discussion highlighted implications for the DD-MM, HPV disclosures, and future interventions.

  7. Posttraumatic growth moderates the effects of posttraumatic stress symptoms on adjustment and positive affective reactions in digestive system cancer patients.

    PubMed

    Ben-Zur, Hasida; Cohen, Miri; Gouzman, Julia

    2015-01-01

    The study aims were twofold: (1) To investigate the associations of posttraumatic stress symptoms (PTSS) and posttraumatic growth (PTG) with adjustment and affective reactions of digestive system cancer patients and (2) To assess the moderating effects of PTG on the associations of PTSS with adjustment and affective reactions. The sample consisted of 200 respondents 1-4 years following diagnosis and treatment for digestive system cancer. Participants completed questionnaires assessing PTSS, PTG, adjustment, positive affect (PA), and negative affect (NA). The results showed that PTG was positively associated with adjustment and PA, while PTSS was negatively associated with these outcomes and positively associated with NA. Moderation effects of PTG were also observed: The negative associations between PTSS and adjustment or PA were weaker under high levels than under low levels of PTG. It was concluded that PTG is important both as a contributor to better adjustment and PA, as well as a moderator of the detrimental effects of PTSS on adjustment and PA following recovery from cancer. Thus, when developing post-cancer intervention programs, PTG should be viewed as a factor to be encouraged and nurtured for the benefit of cancer patients' adjustment and their long-term well-being.

  8. [Metrological analysis of measuring systems in testing an anticipatory reaction to the position of a moving object].

    PubMed

    Aksiuta, E F; Ostashev, A V; Sergeev, E V; Aksiuta, V E

    1997-01-01

    The methods of the information (entropy) error theory were used to make a metrological analysis of the well-known commercial measuring systems for timing an anticipative reaction (AR) to the position of a moving object, which is based on the electromechanical, gas-discharge, and electron principles. The required accuracy of measurement was ascertained to be achieved only by using the systems based on the electron principle of moving object simulation and AR measurement.

  9. An Azulene-Based Discovery Experiment: Challenging Students to Watch for the "False Assumption"

    ERIC Educational Resources Information Center

    Garner, Charles M.

    2005-01-01

    A discovery-based experiment is developed depending on a "false assumption" that the students mistakenly assume they know the structure of a reaction product and are forced to reconcile observations that are inconsistent with this assumption. This experiment involves the chemistry of azulenes, an interesting class of intensely colored aromatic…

  10. [Reactions to food].

    PubMed

    Halvorsen, R; Eggesb M; Botten, G

    1995-12-10

    Adverse reactions to food occur in about 1-2% of the population, but are reported more frequently by patients. Most reactions to food are not caused by allergy. IgE-mediated food reactions are well known and of major clinical significance owing to their potentially dangerous, even life-threatening character. Adverse reactions to food can also be caused by immunological mechanisms other than IgE-mediated reactions such as, enzyme deficiencies, active pharmacological substances in food and psychological mechanisms. Double-blind provocation is the only way to diagnose a positive reaction to a food item with some certainty. Regretably no objective measures for food reactions exist.

  11. Apheresis technology correlates with bacterial contamination of platelets and reported septic transfusion reactions.

    PubMed

    Eder, Anne F; Dy, Beth A; DeMerse, Barbara; Wagner, Stephen J; Stramer, Susan L; O'Neill, E Mary; Herron, Ross M

    2017-12-01

    Apheresis technology to collect platelet (PLT) components differs among devices. We evaluated the relationship of the plateletpheresis device with bacterial contamination and reported septic transfusion reactions. Plateletpheresis was performed using Amicus (Fenwal, a Fresenius Kabi Company) or Trima (Trima Accel, TerumoBCT) from 2010 to 2014. All donations used inlet-line sample diversion and were tested by quality control (QC; Day 1) aerobic culture. Rates of bacterial contamination and septic reactions to PLTs were calculated for both devices. During the 5-year study period, plateletpheresis collections using Amicus and Trima devices totaled 1,486,888 and 671,955 donations, respectively. The rate of confirmed-positive bacterial cultures of apheresis PLT donations was significantly higher with Amicus than with Trima (252 vs. 112 per 10 6 donations [odds ratio {OR}, 2.3; 95% confidence interval {CI}, 1.8-2.9]). Septic transfusion reactions were caused by 30 apheresis PLT units from 25 contaminated Amicus procedures and three apheresis PLT units from three contaminated Trima procedures. The overall rate of septic reactions was significantly higher with apheresis PLT components collected with Amicus than with Trima (16.8 vs. 4.5 per 10 6 donations [OR, 3.8; 95% CI, 1.1-12.5]). All apheresis PLT components implicated in septic transfusion reactions had negative QC culture results incubated through Day 5 (i.e., false negatives). Apheresis technology affects bacterial contamination of plateletpheresis collections. The device-specific, higher rate of confirmed-positive bacterial culture results also correlated with a significantly higher rate of reported septic transfusion reactions to apheresis PLTs. © 2017 AABB.

  12. Veridical and false recall in adults who stutter.

    PubMed

    Byrd, Courtney T; Sheng, Li; Ratner, Nan Bernstein; Gkalitsiou, Zoi

    2015-02-01

    This study used a false memory paradigm to explore the veridical and false recall of adults who stutter. Twelve adults who stutter and 12 age-matched typically fluent peers listened to and then verbally recalled lists of words that consisted of either semantic or phonological associates or an equal number of semantic and phonological associates (i.e., hybrid condition) of a single, unpresented critical "lure" word. Three parameters of recall performance were measured across these 3 conditions: (a) number of accurately recalled words, (b) order of recall (primacy vs. recency effect), and (c) number of critical lures produced (i.e., false memories). Significant group differences were noted in recall accuracy specific to list type and also list position as well as relative to critical lure productions. Results suggest that certain basic memory processes (i.e., recency effect) and the processing of gist semantic information are largely intact in adults who stutter, but recall of verbatim phonological information and subvocal rehearsal may be deficient.

  13. Children's False Memory and True Disclosure in the Face of Repeated Questions

    ERIC Educational Resources Information Center

    Schaaf, Jennifer M.; Alexander, Kristen Weede; Goodman, Gail S.

    2008-01-01

    The current study was designed to investigate children's memory and suggestibility for events differing in valence (positive or negative) and veracity (true or false). A total of 82 3- and 5-year-olds were asked repeated questions about true and false events, either in a grouped order (i.e., all questions about a certain event asked consecutively)…

  14. Technical adequacy of bisulfite sequencing and pyrosequencing for detection of mitochondrial DNA methylation: Sources and avoidance of false-positive detection.

    PubMed

    Owa, Chie; Poulin, Matthew; Yan, Liying; Shioda, Toshi

    2018-01-01

    The existence of cytosine methylation in mammalian mitochondrial DNA (mtDNA) is a controversial subject. Because detection of DNA methylation depends on resistance of 5'-modified cytosines to bisulfite-catalyzed conversion to uracil, examined parameters that affect technical adequacy of mtDNA methylation analysis. Negative control amplicons (NCAs) devoid of cytosine methylation were amplified to cover the entire human or mouse mtDNA by long-range PCR. When the pyrosequencing template amplicons were gel-purified after bisulfite conversion, bisulfite pyrosequencing of NCAs did not detect significant levels of bisulfite-resistant cytosines (brCs) at ND1 (7 CpG sites) or CYTB (8 CpG sites) genes (CI95 = 0%-0.94%); without gel-purification, significant false-positive brCs were detected from NCAs (CI95 = 4.2%-6.8%). Bisulfite pyrosequencing of highly purified, linearized mtDNA isolated from human iPS cells or mouse liver detected significant brCs (~30%) in human ND1 gene when the sequencing primer was not selective in bisulfite-converted and unconverted templates. However, repeated experiments using a sequencing primer selective in bisulfite-converted templates almost completely (< 0.8%) suppressed brC detection, supporting the false-positive nature of brCs detected using the non-selective primer. Bisulfite-seq deep sequencing of linearized, gel-purified human mtDNA detected 9.4%-14.8% brCs for 9 CpG sites in ND1 gene. However, because all these brCs were associated with adjacent non-CpG brCs showing the same degrees of bisulfite resistance, DNA methylation in this mtDNA-encoded gene was not confirmed. Without linearization, data generated by bisulfite pyrosequencing or deep sequencing of purified mtDNA templates did not pass the quality control criteria. Shotgun bisulfite sequencing of human mtDNA detected extremely low levels of CpG methylation (<0.65%) over non-CpG methylation (<0.55%). Taken together, our study demonstrates that adequacy of mtDNA methylation analysis

  15. Predicting radiologists' true and false positive decisions in reading mammograms by using gaze parameters and image-based features

    NASA Astrophysics Data System (ADS)

    Gandomkar, Ziba; Tay, Kevin; Ryder, Will; Brennan, Patrick C.; Mello-Thoms, Claudia

    2016-03-01

    Radiologists' gaze-related parameters combined with image-based features were utilized to classify suspicious mammographic areas ultimately scored as True Positives (TP) and False Positives (FP). Eight breast radiologists read 120 two-view digital mammograms of which 59 had biopsy proven cancer. Eye tracking data was collected and nearby fixations were clustered together. Suspicious areas on mammograms were independently identified based on thresholding an intensity saliency map followed by automatic segmentation and pruning steps. For each radiologist reported area, radiologist's fixation clusters in the area, as well as neighboring suspicious areas within 2.5° of the center of fixation, were found. A 45-dimensional feature vector containing gaze parameters of the corresponding cluster along with image-based characteristics was constructed. Gaze parameters included total number of fixations in the cluster, dwell time, time to hit the cluster for the first time, maximum number of consecutive fixations, and saccade magnitude of the first fixation in the cluster. Image-based features consisted of intensity, shape, and texture descriptors extracted from the region around the suspicious area, its surrounding tissue, and the entire breast. For each radiologist, a userspecific Support Vector Machine (SVM) model was built to classify the reported areas as TPs or FPs. Leave-one-out cross validation was utilized to avoid over-fitting. A feature selection step was embedded in the SVM training procedure by allowing radial basis function kernels to have 45 scaling factors. The proposed method was compared with the radiologists' performance using the jackknife alternative free-response receiver operating characteristic (JAFROC). The JAFROC figure of merit increased significantly for six radiologists.

  16. Two cases of false-positive dengue non-structural protein 1 (NS1) antigen in patients with hematological malignancies and a review of the literature on the use of NS1 for the detection of Dengue infection.

    PubMed

    Chung, Shimin J; Krishnan, Prabha U; Leo, Yee Sin

    2015-02-01

    Early diagnosis of dengue has been made easier in recent years owing to the advancement in diagnostic technologies. The rapid non-structural protein 1 (NS1) test strip is widely used in many developed and developing regions at risk of dengue. Despite the relatively high specificity of this test, we recently encountered two cases of false-positive dengue NS1 antigen in patients with underlying hematological malignancies. We reviewed the literature for causes of false-positive dengue NS1. © The American Society of Tropical Medicine and Hygiene.

  17. Assessment of two malaria rapid diagnostic tests in children under five years of age, with follow-up of false-positive pLDH test results, in a hyperendemic falciparum malaria area, Sierra Leone.

    PubMed

    Gerstl, Sibylle; Dunkley, Sophie; Mukhtar, Ahmed; De Smet, Martin; Baker, Samuel; Maikere, Jacob

    2010-01-21

    Most malaria rapid diagnostic tests (RDTs) use HRP2 detection, including Paracheck-Pf(R), but their utility is limited by persistent false positivity after treatment. PLDH-based tests become negative more quickly, but sensitivity has been reported below the recommended standard of 90%. A new pLDH test, CareStart three-line P.f/PAN-pLDH, claims better sensitivity with continued rapid conversion to negative. The study aims were to 1) compare sensitivity and specificity of CareStart to Paracheck-Pf(R) to diagnose falciparum malaria in children under five years of age, 2) assess how quickly false-positive CareStart tests become negative and 3) evaluate ease of use and inter-reader agreement of both tests. Participants were included if they were aged between two and 59 months, presenting to a Médecins Sans Frontières community health centre in eastern Sierra Leone with suspected malaria defined as fever (axillary temperature > 37.5 degrees C) and/or history of fever in the previous 72 hours and no signs of severe disease. The same capillary blood was used for the RDTs and the blood slide, the latter used as the gold standard reference. All positive participants were treated with supervised artesunate and amodiaquine treatment for three days. Participants with a persistent false-positive CareStart, but a negative blood slide on Day 2, were followed with repeated CareStart and blood slide tests every seven days until CareStart became negative or a maximum of 28 days. Sensitivity of CareStart was 99.4% (CI 96.8-100.0, 168/169) and of Paracheck-Pf(R), 98.8% (95% CI 95.8-99.8, 167/169). Specificity of CareStart was 96.0% (CI 91.9-98.4, 167/174) and of Paracheck-Pf(R), 74.7% (CI 67.6-81.0, 130/174) (p < 0.001). Neither test showed any change in sensitivity with decreasing parasitaemia. Of the 155 eligible follow-up CareStart participants, 63.9% (99/155) had a false-positive test on day 2, 21.3% (33/155) on day 7, 5.8% (9/155) on day 14, 1.9% (3/155) on day 21 and 0.6% (1

  18. False memory in aging: effects of emotional valence on word recognition accuracy.

    PubMed

    Piguet, Olivier; Connally, Emily; Krendl, Anne C; Huot, Jessica R; Corkin, Suzanne

    2008-06-01

    Memory is susceptible to distortions. Valence and increasing age are variables known to affect memory accuracy and may increase false alarm production. Interaction between these variables and their impact on false memory was investigated in 36 young (18-28 years) and 36 older (61-83 years) healthy adults. At study, participants viewed lists of neutral words orthographically related to negative, neutral, or positive critical lures (not presented). Memory for these words was subsequently tested with a remember-know procedure. At test, items included the words seen at study and their associated critical lures, as well as sets of orthographically related neutral words not seen at study and their associated unstudied lures. Positive valence was shown to have two opposite effects on older adults' discrimination of the lures: It improved correct rejection of unstudied lures but increased false memory for critical lures (i.e., lures associated with words studied previously). Thus, increased salience triggered by positive valence may disrupt memory accuracy in older adults when discriminating among similar events. These findings likely reflect a source memory deficit due to decreased efficiency in cognitive control processes with aging.

  19. Positive patch test reactions to oxidized limonene: exposure and relevance.

    PubMed

    Bråred Christensson, Johanna; Andersen, Klaus E; Bruze, Magnus; Johansen, Jeanne D; Garcia-Bravo, Begoña; Gimenez Arnau, Ana; Goh, Chee-Leok; Nixon, Rosemary; White, Ian R

    2014-11-01

    R-Limonene is a common fragrance terpene found in domestic and industrial products. R-Limonene autoxidizes on air exposure, and the oxidation products can cause contact allergy. In a recent multicentre study, 5.2% (range 2.3-12.1%) of 2900 patients showed a positive patch test reaction to oxidized R-limonene. To study the exposure to limonene among consecutive dermatitis patients reacting to oxidized R-limonene in an international setting, and to assess the relevance of the exposure for the patients' dermatitis. Oxidized R-limonene 3.0% (containing limonene hydroperoxides at 0.33%) in petrolatum was tested in 2900 consecutive dermatitis patients in Australia, Denmark, the United Kingdom, Singapore, Spain, and Sweden. A questionnaire assessing exposure to limonene-containing products was completed. Overall, exposure to products containing limonene was found and assessed as being probably relevant for the patients' dermatitis in 36% of the limonene-allergic patients. In Barcelona and Copenhagen, > 70% of the patients were judged to have had an exposure to limonene assessed as relevant. Oxidized R-limonene is a common fragrance allergen, and limonene was frequently found in the labelling on the patients' products, and assessed as relevant for the patients' dermatitis. A large number of domestic and occupational sources for contact with R-limonene were identified. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Teacher Education and the Enduring Significance of "False Empathy"

    ERIC Educational Resources Information Center

    Warren, Chezare A.; Hotchkins, Bryan K.

    2015-01-01

    The concept "False Empathy" posited by critical race theory luminary Richard Delgado ("Calif Law Rev" 84(1):61-100, 1996) easily obscures White teacher's good intentions to be effective educators of racially, culturally, and linguistically diverse students. It is argued here that critical race theory is useful for isolating and…

  1. Ab initio study of nitrogen and position-specific oxygen kinetic isotope effects in the NO + O3 reaction

    NASA Astrophysics Data System (ADS)

    Walters, Wendell W.; Michalski, Greg

    2016-12-01

    Ab initio calculations have been carried out to investigate nitrogen (k15/k14) and position-specific oxygen (k17/k16O & k18/k16) kinetic isotope effects (KIEs) for the reaction between NO and O3 using CCSD(T)/6-31G(d) and CCSD(T)/6-311G(d) derived frequencies in the complete Bigeleisen equations. Isotopic enrichment factors are calculated to be -6.7‰, -1.3‰, -44.7‰, -14.1‰, and -0.3‰ at 298 K for the reactions involving the 15N16O, 14N18O, 18O16O16O, 16O18O16O, and 16O16O18O isotopologues relative to the 14N16O and 16O3 isotopologues, respectively (CCSD(T)/6-311G(d)). Using our oxygen position-specific KIEs, a kinetic model was constructed using Kintecus, which estimates the overall isotopic enrichment factors associated with unreacted O3 and the oxygen transferred to NO2 to be -19.6‰ and -22.8‰, respectively, (CCSD(T)/6-311G(d)) which tends to be in agreement with previously reported experimental data. While this result may be fortuitous, this agreement suggests that our model is capturing the most important features of the underlying physics of the KIE associated with this reaction (i.e., shifts in zero-point energies). The calculated KIEs will useful in future NOx isotopic modeling studies aimed at understanding the processes responsible for the observed tropospheric isotopic variations of NOx as well as for tropospheric nitrate.

  2. The effects of increasing semantic-associate list length on the Deese-Roediger-McDermott false recognition memory: Dual false-memory process in retrieval from sub- and supraspan lists.

    PubMed

    Jou, Jerwen; Arredondo, Mario L; Li, Cheng; Escamilla, Eric E; Zuniga, Richard

    2017-10-01

    In this study, the number of semantic associates in Deese-Roediger-McDermott (DRM) lists was varied from 4 to 14 in a modified Sternberg paradigm. The false alarm (FA) and correct rejection (CR) reaction time (RT)/memory-set size (MSS) functions of critical lures showed a cross-over interaction at approximately MSS 7, suggesting a reversal of the relative dominance between these two responses to the critical lure at this point and also indicating the location of the boundary between the sub- and supraspan MSS. For the subspan lists, FA to critical lures was slower than CR, suggesting a slow, strategic mechanism driving the false memory. Conversely, for the supraspan lists, critical lure FA was faster than its CR, suggesting a spontaneous mechanism driving the false memory. Results of two experiments showed that an automatic, fast, and a slow, controlled process could be error-prone or error-corrective, depending on the length of the DRM memory list. Thus there is a dual retrieval process in false memory as in true memory. The findings can be explained by both the activation/monitoring and the fuzzy-trace theories.

  3. Discrete emotion-congruent false memories in the DRM paradigm.

    PubMed

    Bland, Cassandra E; Howe, Mark L; Knott, Lauren

    2016-08-01

    Research has shown that false-memory production is enhanced for material that is emotionally congruent with the mood of the participant at the time of encoding. So far this research has only been conducted to examine the influence of generic negative affective mood states and generic negative stimuli on false-memory production. In addition, much of the research is limited as it focuses on valence and arousal dimensions, and fails to take into account the more comprehensive nature of emotions. The current study demonstrates that this effect goes beyond general negative or positive moods and acts at a more discrete emotional level. Participants underwent a standard emotion-induction procedure before listening to negative emotional or neutral associative word lists. The emotions induced, negative word lists, and associated nonpresented critical lures, were related to either fear or anger, 2 negative valence emotions that are also both high in arousal. Results showed that when valence and arousal are controlled for, false memories are more likely to be produced for discrete emotionally congruent compared with incongruent materials. These results support spreading activation theories of false remembering and add to our understanding of the adaptive nature of false-memory production. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  4. Substrate-Directed Catalytic Selective Chemical Reactions.

    PubMed

    Sawano, Takahiro; Yamamoto, Hisashi

    2018-05-04

    The development of highly efficient reactions at only the desired position is one of the most important subjects in organic chemistry. Most of the reactions in current organic chemistry are reagent- or catalyst-controlled reactions, and the regio- and stereoselectivity of the reactions are determined by the inherent nature of the reagent or catalyst. In sharp contrast, substrate-directed reaction determines the selectivity of the reactions by the functional group on the substrate and can strictly distinguish sterically and electronically similar multiple reaction sites in the substrate. In this Perspective, three topics of substrate-directed reaction are mainly reviewed: (1) directing group-assisted epoxidation of alkenes, (2) ring-opening reactions of epoxides by various nucleophiles, and (3) catalytic peptide synthesis. Our newly developed synthetic methods with new ligands including hydroxamic acid derived ligands realized not only highly efficient reactions but also pinpointed reactions at the expected position, demonstrating the substrate-directed reaction as a powerful method to achieve the desired regio- and stereoselective functionalization of molecules from different viewpoints of reagent- or catalyst-controlled reactions.

  5. False Positive Stress Testing: Does Endothelial Vascular Dysfunction Contribute to ST-Segment Depression in Women? A Pilot Study.

    PubMed

    Sharma, Shilpa; Mehta, Puja K; Arsanjani, Reza; Sedlak, Tara; Hobel, Zachary; Shufelt, Chrisandra; Jones, Erika; Kligfield, Paul; Mortara, David; Laks, Michael; Diniz, Marcio; Bairey Merz, C Noel

    2018-06-19

    The utility of exercise-induced ST-segment depression for diagnosing ischemic heart disease (IHD) in women is unclear. Based on evidence that IHD pathophysiology in women involves coronary vascular dysfunction, we hypothesized that coronary vascular dysfunction contributes to exercise electrocardiography (Ex-ECG) ST-depression in the absence of obstructive CAD, so-called "false positive" results. We tested our hypothesis in a pilot study evaluating the relationship between peripheral vascular endothelial function and Ex-ECG. Twenty-nine asymptomatic women without cardiac risk factors underwent maximal Bruce protocol exercise treadmill testing and peripheral endothelial function assessment using peripheral arterial tonometry (Itamar EndoPAT 2000) to measure reactive hyperemia index (RHI). The relationship between RHI and Ex-ECG ST-segment depression was evaluated using logistic regression and differences in subgroups using two-tailed t-tests. Mean age was 54 ± 7 years, body mass index 25 ± 4 kg/m 2 , and RHI 2.51 ± 0.66. Three women (10%) had RHI less than 1.68, consistent with abnormal peripheral endothelial function, while 18 women (62%) met criteria for a positive Ex-ECG based on ST-segment depression in contiguous leads. Women with and without ST-segment depression had similar baseline and exercise vital signs, metabolic equivalents (METS) achieved, and RHI (all p>0.05). RHI did not predict ST-segment depression. Our pilot study demonstrates a high prevalence of exercise-induced ST-segment depression in asymptomatic, middle-aged, overweight women. Peripheral vascular endothelial dysfunction did not predict Ex-ECG ST-segment depression. Further work is needed to investigate the utility of vascular endothelial testing and Ex-ECG for IHD diagnostic and management purposes in women. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluoric acid, reaction products... Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... hydrofluoric acid, reaction products with heptane (PMN P-98-1036; CAS No. 207409-71-0) is subject to reporting...

  7. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluoric acid, reaction products... Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... hydrofluoric acid, reaction products with heptane (PMN P-98-1036; CAS No. 207409-71-0) is subject to reporting...

  8. Immediate reactions to iodinated contrast media.

    PubMed

    Morales-Cabeza, Cristina; Roa-Medellín, Dasha; Torrado, Inés; De Barrio, Manuel; Fernández-Álvarez, Carmen; Montes-Aceñero, Juan Francisco; De La Riva, Inmaculada; Prieto-García, Alicia

    2017-12-01

    Immediate hypersensitivity reactions (IHRs) to iodinated contrast media (ICMs) remain a common clinical concern. Positive skin test and basophil activation test results suggest a specific IgE-mediated mechanism in some cases. Skin test and controlled challenge test (CCT) are useful to manage these patients. To study clinical and allergologic features of IHRs to ICMs in a Spanish tertiary hospital during a 7-year period. Demographic and clinical data concerning the reaction were recorded. Patients treated at the Allergy Department of Hospital General Universitario Gregorio Marañón, Madrid, Spain, underwent skin tests. In those with positive results, CCTs with an alternative skin-test-negative ICM was performed. Global reaction rate was calculated and compared for each ICM. A total of 342 reactions occurred in 329 patients. Cutaneous symptoms were the most common (87.7%). A total of 196 patients underwent an allergy workup, 15 (7.6%) of whom had positive skin test results. Reactions were more severe in patients with positive vs negative skin test results (grade 1, 46.7% vs 73.6%; grade 2, 33.3% vs 20.9%; grade 3, 20% vs 5.46%; P < .05). Three patients had cross-reactivity to 3 ICMs, all including ioversol and iomeprol. Six patients allergic to iopamidol tolerated ioversol and 1 tolerated iomeprol. Four patients allergic to ioversol and 1 allergic to iomeprol tolerated iopamidol. The global reaction rate was 0.2%, differing for each ICM (iopamidol, 0.14%; ioversol, 0.2%; and iomeprol, 0.4%; P < .001). Positive skin test results were found in a low percentage of patients in whom skin test-based CCT identified an alternative non-cross-reactive ICM. Low-grade cross-reactivity was found, especially between iopamidol and ioversol. Reactions were more severe in patients with positive skin test results. The reaction rate was greater for iomeprol compared with iopamidol (reaction rate, 2.8%) and ioversol (reaction rate, 2%). This study identified a possible underlying

  9. Windstreaks -- False Color

    NASA Image and Video Library

    2015-01-30

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows windstreaks in Daedalia Planum.

  10. Siblings, Language, and False Belief in Low-Income Children

    ERIC Educational Resources Information Center

    Tompkins, Virginia; Farrar, M. Jeffrey; Guo, Ying

    2013-01-01

    The authors examined the relationship between number of siblings and false belief understanding (FBU) in 94 low-income 4-5-year-olds. Previous research with middle-income children has shown a positive association between number of siblings and FBU. However, it is unclear whether having multiple siblings in low-income families is related to better…

  11. Maltreatment increases spontaneous false memories but decreases suggestion-induced false memories in children.

    PubMed

    Otgaar, Henry; Howe, Mark L; Muris, Peter

    2017-09-01

    We examined the creation of spontaneous and suggestion-induced false memories in maltreated and non-maltreated children. Maltreated and non-maltreated children were involved in a Deese-Roediger-McDermott false memory paradigm where they studied and remembered negative and neutral word lists. Suggestion-induced false memories were created using a misinformation procedure during which both maltreated and non-maltreated children viewed a negative video (i.e., bank robbery) and later received suggestive misinformation concerning the event. Our results showed that maltreated children had higher levels of spontaneous negative false memories but lower levels of suggestion-induced false memories as compared to non-maltreated children. Collectively, our study demonstrates that maltreatment both increases and decreases susceptibility to memory illusions depending on the type of false memory being induced. Statement of contribution What is already known on this subject? Trauma affects memory. It is unclear how trauma affects false memory. What does this study add? This study focuses on two types of false memories. © 2017 The Authors. British Journal of Developmental Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

  12. Crater - False Color

    NASA Image and Video Library

    2015-01-14

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows an unnamed crater in Acidalia Planitia.

  13. Positive Patch-Test Reactions to Essential Oils in Consecutive Patients From North America and Central Europe.

    PubMed

    Warshaw, Erin M; Zug, Kathryn A; Belsito, Donald V; Fowler, Joseph F; DeKoven, Joel G; Sasseville, Denis; Maibach, Howard I; Mathias, C G Toby; DeLeo, Vincent A; Taylor, James S; Fransway, Anthony F; Marks, James G; Pratt, Melanie D; Zirwas, Matthew J; Geier, Johannes; Uter, Wolfgang

    Synthetic fragrances and natural essential oils (EOs) are used in perfumery and found in various cosmetics. Essential oils are also increasingly used to promote wellness. In previous studies, the sensitization potential of some EOs has been identified; however, the current prevalence of sensitivity is largely unknown. The aim of this study was to determine frequency of positive patch-test reactions to EOs tested in the baseline series, along with 3 fragrance markers (FMs) (fragrance mix I, fragrance mix II, and Myroxylon pereirae), in consecutive patients in the US/Canadian North American Contact Dermatitis Group (NACDG) (2009-2014) and the central European, trinational Information Network of Departments of Dermatology (IVDK) (2010-2014). This study used a retrospective analysis of patch-test results and relevant demographic/clinical data collected electronically by the networks, obtained with Santalum album 10% petrolatum (pet) (IVDK only); Cananga odorata 2% (NACDG) and 10% (IVDK) pet; Jasminum species 2% (NACDG) and 5% (IVDK) pet; Mentha piperita 2% pet; Melaleuca alternifolia, oxidized (tea tree oil), 5% pet; and Lavandula angustifolia 2% pet (latter 3 NACDG only). Overall, 62,354 patients were tested to 3 FMs and EOs (NACDG, 13,398; IVDK, 48,956); 11,568 (18.6%) reacted to at least 1 FM or EO, whereas 857 (1.4%) reacted to 1 or more EOs but none of the 3 FMs. For both the NACDG and IVDK populations, individuals who were positive to 1 or more of the 9 study allergens were significantly less likely to be male, have occupational skin disease, or have hand involvement and significantly more likely to have leg dermatitis and be 40 years and older (P's ≤ 0.005). Prevalence rates for EOs were as follows: S. album, 1.4% IVDK; C. odorata, 1.1% NACDG and 2.4% IVDK; Jasminum species, 0.7% NACDG and 1.4% IVDK; M. piperita, 0.9% NACDG; L. angustifolia, 0.3% NACDG; and M. alternifolia, 0.3% NACDG. Of the 140 NACDG patients who reacted to 1 or more of the 5 NACDG EOs but

  14. Pharmacovigilance data mining with methods based on false discovery rates: a comparative simulation study.

    PubMed

    Ahmed, I; Thiessard, F; Miremont-Salamé, G; Bégaud, B; Tubert-Bitter, P

    2010-10-01

    The early detection of adverse reactions caused by drugs that are already on the market is the prime concern of pharmacovigilance efforts; the methods in use for postmarketing surveillance are aimed at detecting signals pointing to potential safety concerns, on the basis of reports from health-care providers and from information available in various databases. Signal detection methods based on the estimation of false discovery rate (FDR) have recently been proposed. They address the limitation of arbitrary detection thresholds of the automatic methods in current use, including those last updated by the US Food and Drug Administration and the World Health Organization's Uppsala Monitoring Centre. We used two simulation procedures to compare the false-positive performances for three current methods: the reporting odds ratio (ROR), the information component (IC), the gamma Poisson shrinkage (GPS), and also for two FDR-based methods derived from the GPS model and Fisher's test. Large differences in FDR rates were associated with the signal-detection methods currently in use. These differences ranged from 0.01 to 12% in an analysis that was restricted to signals with at least three reports. The numbers of signals generated were also highly variable. Among fixed-size lists of signals, the FDR was lowered when the FDR-based approaches were used. Overall, the outcomes in both simulation studies suggest that improvement in effectiveness can be expected from use of the FDR-based GPS method.

  15. Channel - False Color

    NASA Image and Video Library

    2015-05-25

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of an unnamed channel in Terra Cimmeria.

  16. False Color Surface

    NASA Image and Video Library

    2014-12-26

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of the region near Nili Fossae.

  17. Crater - False Color

    NASA Image and Video Library

    2015-05-26

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of an unnamed crater in Terra Cimmeria.

  18. The prevalence of positive reactions in the atopy patch test with aeroallergens and food allergens in subjects with atopic eczema: a European multicenter study.

    PubMed

    Darsow, U; Laifaoui, J; Kerschenlohr, K; Wollenberg, A; Przybilla, B; Wüthrich, B; Borelli, S; Giusti, F; Seidenari, S; Drzimalla, K; Simon, D; Disch, R; Borelli, S; Devillers, A C A; Oranje, A P; De Raeve, L; Hachem, J-P; Dangoisse, C; Blondeel, A; Song, M; Breuer, K; Wulf, A; Werfel, T; Roul, S; Taieb, A; Bolhaar, S; Bruijnzeel-Koomen, C; Brönnimann, M; Braathen, L R; Didierlaurent, A; André, C; Ring, J

    2004-12-01

    The atopy patch test (APT) was proposed to evaluate IgE-mediated sensitizations in patients with atopic eczema (AE). The prevalence and agreement with clinical history and specific IgE (sIgE) of positive APT reactions was investigated in six European countries using a standardized method. A total of 314 patients with AE in remission were tested in 12 study centers on clinically uninvolved, non-abraded back skin with 200 index of reactivity (IR)/g of house dust mite Dermatophagoides pteronyssinus, cat dander, grass, and birch pollen allergen extracts with defined major allergen contents in petrolatum. Extracts of egg white, celery and wheat flour with defined protein content were also patch tested. APT values were evaluated at 24, 48, and 72 h according to the European Task Force on Atopic Dermatitis (ETFAD) guidelines. In addition, skin-prick test (SPT) and sIgE and a detailed history on allergen-induced eczema flares were obtained. Previous eczema flares, after contact with specific allergens, were reported in 1% (celery) to 34% (D. pteronyssinus) of patients. The frequency of clear-cut positive APT reactions ranged from 39% with D. pteronyssinus to 9% with celery. All ETFAD intensities occured after 48 and 72 h. Positive SPT (16-57%) and elevated sIgE (19-59%) results were more frequent. Clear-cut positive APT with all SPT and sIgE testing negative was seen in 7% of the patients, whereas a positive APT without SPT or sIgE for the respective allergen was seen in 17% of the patients. APT, SPT and sIgE results showed significant agreement with history for grass pollen and egg white (two-sided Pr > /Z/ < or = 0.01). In addition, SPT and sIgE showed significant agreement with history for the other aeroallergens. With regard to clinical history, the APT had a higher specificity (64-91% depending on the allergen) than SPT (50-85%) or sIgE (52-85%). Positive APT were associated with longer duration of eczema flares and showed regional differences. In 10 non

  19. Toward the breast screening balance sheet: cumulative risk of false positives for annual versus biennial mammograms commencing at age 40 or 50.

    PubMed

    Winch, Caleb J; Sherman, Kerry A; Boyages, John

    2015-01-01

    This study aimed to: (1) Estimate cumulative risk of recall from breast screening where no cancer is detected (a harm) in Australia; (2) Compare women screened annually versus biennially, commencing age 40 versus 50; and (3) Compare with international findings. At the no-cost metropolitan program studied, women attended biennial screening, but were offered annual screening if regarded at elevated risk for breast cancer. The cumulative risk of at least one recall was estimated using discrete-time survival analysis. Cancer detection statistics were computed. In total, 801,636 mammograms were undertaken in 231,824 women. Over 10 years, cumulative risk of recall was 13.3 % (95 % CI 12.7-13.8) for those screened biennially, and 19.9 % (CI 16.6-23.2) for those screened annually from age 50-51. Cumulative risk of complex false positive involving a biopsy was 3.1 % (CI 2.9-3.4) and 5.0 % (CI 3.4-6.6), respectively. From age 40-41, the risk of recall was 15.1 % (CI 14.3-16.0) and 22.5 % (CI 17.9-27.1) for biennial and annual screening, respectively. Corresponding rates of complex false positive were 3.3 % (CI 2.9-3.8) and 6.3 % (CI 3.4-9.1). Over 10 mammograms, invasive cancer was detected in 3.4 % (CI 3.3-3.5) and ductal carcinoma in situ in 0.7 % (CI 0.6-0.7) of women, with a non-significant trend toward a larger proportion of Tis and T1N0 cancers in women screened annually (74.5 %) versus biennially (70.1 %), χ (2) = 2.77, p = 0.10. Cancer detection was comparable to international findings. Recall risk was equal to European estimates for women screening from 50 and lower for screening from 40. Recall risk was half of United States' rates across start age and rescreening interval categories. Future benefit/harm balance sheets may be useful for communicating these findings to women.

  20. Cellular and Biophysical Pipeline for the Screening of Peroxisome Proliferator-Activated Receptor Beta/Delta Agonists: Avoiding False Positives

    PubMed Central

    Batista, Fernanda Aparecida Heleno

    2018-01-01

    Peroxisome proliferator-activated receptor beta/delta (PPARß/δ) is considered a therapeutic target for metabolic disorders, cancer, and cardiovascular diseases. Here, we developed one pipeline for the screening of PPARß/δ agonists, which reduces the cost, time, and false-positive hits. The first step is an optimized 3-day long cellular transactivation assay based on reporter-gene technology, which is supported by automated liquid-handlers. This primary screening is followed by a confirmatory transactivation assay and by two biophysical validation methods (thermal shift assay (TSA) and (ANS) fluorescence quenching), which allow the calculation of the affinity constant, giving more information about the selected hits. All of the assays were validated using well-known commercial agonists providing trustworthy data. Furthermore, to validate and test this pipeline, we screened a natural extract library (560 extracts), and we found one plant extract that might be interesting for PPARß/δ modulation. In conclusion, our results suggested that we developed a cheaper and more robust pipeline that goes beyond the single activation screening, as it also evaluates PPARß/δ tertiary structure stabilization and the ligand affinity constant, selecting only molecules that directly bind to the receptor. Moreover, this approach might improve the effectiveness of the screening for agonists that target PPARß/δ for drug development.

  1. 40 CFR 721.9265 - Reaction product of dichlorobenzidine and substituted alkylamide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction product of dichlorobenzidine... Significant New Uses for Specific Chemical Substances § 721.9265 Reaction product of dichlorobenzidine and... substance identified generically as a reaction product of dichlorobenzidine and substituted alkylamide (PMN...

  2. 40 CFR 721.9265 - Reaction product of dichlorobenzidine and substituted alkylamide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction product of dichlorobenzidine... Significant New Uses for Specific Chemical Substances § 721.9265 Reaction product of dichlorobenzidine and... substance identified generically as a reaction product of dichlorobenzidine and substituted alkylamide (PMN...

  3. 40 CFR 721.10210 - Soybean oil, epoxidized, reaction products with diethanolamine.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Soybean oil, epoxidized, reaction... Significant New Uses for Specific Chemical Substances § 721.10210 Soybean oil, epoxidized, reaction products... chemical substance identified as soybean oil, epoxidized, reaction products with diethanolamine (PMN P-09...

  4. Massive-training artificial neural network (MTANN) for reduction of false positives in computer-aided detection of polyps: Suppression of rectal tubes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Suzuki, Kenji; Yoshida, Hiroyuki; Naeppi, Janne

    2006-10-15

    One of the limitations of the current computer-aided detection (CAD) of polyps in CT colonography (CTC) is a relatively large number of false-positive (FP) detections. Rectal tubes (RTs) are one of the typical sources of FPs because a portion of a RT, especially a portion of a bulbous tip, often exhibits a cap-like shape that closely mimics the appearance of a small polyp. Radiologists can easily recognize and dismiss RT-induced FPs; thus, they may lose their confidence in CAD as an effective tool if the CAD scheme generates such ''obvious'' FPs due to RTs consistently. In addition, RT-induced FPs maymore » distract radiologists from less common true positives in the rectum. Therefore, removal RT-induced FPs as well as other types of FPs is desirable while maintaining a high sensitivity in the detection of polyps. We developed a three-dimensional (3D) massive-training artificial neural network (MTANN) for distinction between polyps and RTs in 3D CTC volumetric data. The 3D MTANN is a supervised volume-processing technique which is trained with input CTC volumes and the corresponding ''teaching'' volumes. The teaching volume for a polyp contains a 3D Gaussian distribution, and that for a RT contains zeros for enhancement of polyps and suppression of RTs, respectively. For distinction between polyps and nonpolyps including RTs, a 3D scoring method based on a 3D Gaussian weighting function is applied to the output of the trained 3D MTANN. Our database consisted of CTC examinations of 73 patients, scanned in both supine and prone positions (146 CTC data sets in total), with optical colonoscopy as a reference standard for the presence of polyps. Fifteen patients had 28 polyps, 15 of which were 5-9 mm and 13 were 10-25 mm in size. These CTC cases were subjected to our previously reported CAD scheme that included centerline-based segmentation of the colon, shape-based detection of polyps, and reduction of FPs by use of a Bayesian neural network based on geometric and

  5. A Comparison between Students Who Receive and Who Do Not Receive a Writing Readiness Interventions on Handwriting Quality, Speed and Positive Reactions

    ERIC Educational Resources Information Center

    Lifshitz, Nirit; Har-Zvi, Shirley

    2015-01-01

    Proper acquisition of handwriting is required for success in school. This study compared the effects of two writing readiness interventions, "Traffic Light" and "Word and Sound" on kindergartners' handwriting quality, speed and positive reactions to writing. Handwriting readiness training for kindergarten children is…

  6. SU-G-BRB-03: Assessing the Sensitivity and False Positive Rate of the Integrated Quality Monitor (IQM) Large Area Ion Chamber to MLC Positioning Errors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boehnke, E McKenzie; DeMarco, J; Steers, J

    2016-06-15

    Purpose: To examine both the IQM’s sensitivity and false positive rate to varying MLC errors. By balancing these two characteristics, an optimal tolerance value can be derived. Methods: An un-modified SBRT Liver IMRT plan containing 7 fields was randomly selected as a representative clinical case. The active MLC positions for all fields were perturbed randomly from a square distribution of varying width (±1mm to ±5mm). These unmodified and modified plans were measured multiple times each by the IQM (a large area ion chamber mounted to a TrueBeam linac head). Measurements were analyzed relative to the initial, unmodified measurement. IQM readingsmore » are analyzed as a function of control points. In order to examine sensitivity to errors along a field’s delivery, each measured field was divided into 5 groups of control points, and the maximum error in each group was recorded. Since the plans have known errors, we compared how well the IQM is able to differentiate between unmodified and error plans. ROC curves and logistic regression were used to analyze this, independent of thresholds. Results: A likelihood-ratio Chi-square test showed that the IQM could significantly predict whether a plan had MLC errors, with the exception of the beginning and ending control points. Upon further examination, we determined there was ramp-up occurring at the beginning of delivery. Once the linac AFC was tuned, the subsequent measurements (relative to a new baseline) showed significant (p <0.005) abilities to predict MLC errors. Using the area under the curve, we show the IQM’s ability to detect errors increases with increasing MLC error (Spearman’s Rho=0.8056, p<0.0001). The optimal IQM count thresholds from the ROC curves are ±3%, ±2%, and ±7% for the beginning, middle 3, and end segments, respectively. Conclusion: The IQM has proven to be able to detect not only MLC errors, but also differences in beam tuning (ramp-up). Partially supported by the Susan Scott

  7. Factors associated with false positives in MDQ screening for bipolar disorder: Insight into the construct validity of the scale.

    PubMed

    Paterniti, Sabrina; Bisserbe, Jean-Claude

    2018-05-29

    Identifying bipolar patients in the first phases of the illness is essential to establish adequate treatment. The goal of this study was to examine the discriminant ability of the Mood Disorders Questionnaire (MDQ) in recognizing bipolar patients referred to a tertiary care structure. Between 2006 and 2012, we assessed 843 individuals referred to the Mood Disorders Program by family physicians in the community. The Structured Clinical Interview for DSM-IV-TR (SCID) was used to assess diagnoses. A nurse collected the information about lifetime symptoms of (hypo)mania in 759 individuals using the MDQ. Univariate chi-square test and logistic regression were used for the statistical analysis. Overall, 86% of the sample had a current anxiety or depressive disorder. When compared to the diagnoses formulated through the SCID, the sensitivity of the MDQ was 75.0%, the specificity was 74%, the positive predictive value was 55%, and the negative predictive value was 88%. Among non-bipolar patients, current post-traumatic stress disorder, borderline personality disorder, current or early remission substance use disorder, and the history of childhood abuse were independently associated with false positive screening using the MDQ. Individuals with current substance use disorders were under-represented, whether or not the patients were aware of their diagnosis of bipolar disorder was not recorded, and the history of childhood abuse was collected based on an open interview. The self-rated measure of the symptoms listed by the MDQ seems to measure a dimension shared by both bipolar disorder and other conditions characterized by affective instability and impulsivity. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. 40 CFR 717.12 - Significant adverse reactions that must be recorded.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Significant adverse reactions that... SIGNIFICANT ADVERSE REACTIONS TO HEALTH OR THE ENVIRONMENT General Provisions § 717.12 Significant adverse reactions that must be recorded. (a) Except as provided in paragraph (b) of this section, significant...

  9. 40 CFR 717.12 - Significant adverse reactions that must be recorded.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Significant adverse reactions that... SIGNIFICANT ADVERSE REACTIONS TO HEALTH OR THE ENVIRONMENT General Provisions § 717.12 Significant adverse reactions that must be recorded. (a) Except as provided in paragraph (b) of this section, significant...

  10. Melas Chasma - False Color

    NASA Image and Video Library

    2015-10-08

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. Today's false color image shows part of the floor of Melas Chasma. The dark blue region in this false color image is sand dunes. Orbit Number: 12061 Latitude: -12.2215 Longitude: 289.105 Instrument: VIS Captured: 2004-09-02 10:11 http://photojournal.jpl.nasa.gov/catalog/PIA19793

  11. High risk of false positive results in a widely used diagnostic test for detection of the porcine reproductive and respiratory syndrome virus (PRRSV).

    PubMed

    Fetzer, C; Pesch, S; Ohlinger, V F

    2006-06-15

    During 2003 and 2004, increasing numbers of positive PRRSV RT-PCR results were reported from herds negative for PRRSV infection. Interestingly, three herds represent nucleus herds with no animal contacts from outside and without clinical symptoms of PRRS until now. Since these positive results that were obtained using a PCR protocol adapted to routine laboratory conditions could not be reproduced with other PRRSV specific RT-PCRs, controlled negative and positive samples were used to examine this phenomenon. A RT-PCR assay for detection and differential diagnosis of the European and North American genotypes of the porcine reproductive and respiratory syndrome virus (PRRSV) according to the method previously published by Oleksiewicz et al. [Oleksiewicz, M.B., Botner, A., Madsen, K.G., Storgaard, T., 1998. Sensitive detection and typing of porcine reproductive and respiratory syndrome virus by RT-PCR amplification of whole viral genes. Vet. Microbiol. 64, 7-22] was investigated in parallel to another recently published method [Pesch, S., 2003. Etablierung einer Nachweismethode für die zwei Genotypen von dem porcine reproductive and respiratory syndrome virus (PRRSV) und ein Beitrag zu seiner molekularen Epidemiologie. Thesis, Institute of Virology, Faculty of Veterinary Medicine, University of Leipzig]. A panel of 228 clinical samples sent in for PRRSV routine diagnostics served as test panel. It was found that both methods have similar analytical sensitivity. However, the primers published by Oleksiewicz were shown to yield a very high proportion of false positive results under routine diagnostic laboratory conditions, i.e. they resulted in RT-PCR products with non-PRRSV sequences, that were indistinguishable from truly positive reagents in standard gel electrophoresis settings. The reason for and possible implications of this finding as well as the risk of modifying published methods without control are discussed.

  12. [Neuropsychological study of false memory in patients with amnesia mild cognitive impairment].

    PubMed

    Xie, Dan-dan; Cheng, Huai-dong; Yin, Chang-lin; Lü, Xin-yi; Wang, Kai

    2011-01-18

    To explore the profile of false memory in aMCI (amnesia mild cognitive impairment) and to elucidate the neuropsychological mechanism of false memory. False memory provoked by pictures and feeling-of-knowing (FOK) test in episodic memory (EM) were conducted in 25 aMCI patients at our hospital from October 2009 to May 2010. And 25 age and education level-matched healthy patients were recruited into the healthy control (HC) group. As compared with HC group, the rate of false memory was higher in the aMCI group. The rate of false memory in recall stage was 26% ± 7% and that of questionnaire stage 28% ± 12%. And the difference between two group was significant (t = 14.437, 7.597, P < 0.05). The FOK-EM of correct judgment and false recognition in the aMCI group (41% ± 10%) was higher than the HC group. And the difference was significant (t = 4.207, P < 0.05). The rates of false memory in recall and questionnaire stages were positively correlated with FOK-EM in aMCI group (r = 0.563, 0.705, P < 0.01). The aMCI patients tend to have more false memory provoked by pictures. The deficit of memory monitoring in aMCI may be the foundation of false memory.

  13. Psychosomatic disorders of gravida status: false and denied pregnancies.

    PubMed

    Kenner, William D; Nicolson, Stephen E

    2015-01-01

    The authors review the literature on two dramatic psychosomatic disorders of reproduction and offer a potential classification of pregnancy denial. Information on false and denied pregnancies is summarized by comparing the descriptions, differential diagnoses, epidemiology, patient characteristics, psychological factors, abdominal tone, and neuroendocrinology. Pregnancy denial's association with neonaticide is reviewed. False and denied pregnancies have fooled women, families, and doctors for centuries as the body obscures her true condition. Improvements in pregnancy testing have decreased reports of false pregnancy. However, recent data suggests 1/475 pregnancies are denied to 20 weeks, and 1/2455 may go undiagnosed to delivery. Factors that may contribute to the unconscious deception include abdominal muscle tone, persistent corpus luteum function, and reduced availability of biogenic amines in false pregnancy, and posture, fetal position, and corpus luteum insufficiency in denied pregnancy. For each condition, there are multiple reports in which the body reveals her true pregnancy status as soon as the woman is convinced of her diagnosis. Forensic literature on denied pregnancy focused on the woman's rejection of motherhood, while psychiatric studies have revealed that trauma and dissociation drive her denial. False pregnancy has firm grounding as a classic psychosomatic disorder. Pregnancy denial's association with neonaticide has led to misleading forensic data, which obscures the central role of trauma and dissociation. A reappraisal of pregnancy denial confirms it as the somatic inverse of false pregnancy. With that perspective, clinicians can help women understand their pregnancy status to avoid unexpected deliveries with tragic outcomes. Copyright © 2015 The Academy of Psychosomatic Medicine. Published by Elsevier Inc. All rights reserved.

  14. Developmental reversals in false memory: Effects of emotional valence and arousal.

    PubMed

    Brainerd, C J; Holliday, R E; Reyna, V F; Yang, Y; Toglia, M P

    2010-10-01

    Do the emotional valence and arousal of events distort children's memories? Do valence and arousal modulate counterintuitive age increases in false memory? We investigated those questions in children, adolescents, and adults using the Cornell/Cortland Emotion Lists, a word list pool that induces false memories and in which valence and arousal can be manipulated factorially. False memories increased with age for unpresented semantic associates of word lists, and net accuracy (the ratio of true memory to total memory) decreased with age. These surprising developmental trends were more pronounced for negatively valenced materials than for positively valenced materials, they were more pronounced for high-arousal materials than for low-arousal materials, and developmental increases in the effects of arousal were small in comparison with developmental increases in the effects of valence. These findings have ramifications for legal applications of false memory research; materials that share the emotional hallmark of crimes (events that are negatively valenced and arousing) produced the largest age increases in false memory and the largest age declines in net accuracy. Copyright 2010 Elsevier Inc. All rights reserved.

  15. False memories for aggressive acts.

    PubMed

    Laney, Cara; Takarangi, Melanie K T

    2013-06-01

    Can people develop false memories for committing aggressive acts? How does this process compare to developing false memories for victimhood? In the current research we used a simple false feedback procedure to implant false memories for committing aggressive acts (causing a black eye or spreading malicious gossip) or for victimhood (receiving a black eye). We then compared these false memories to other subjects' true memories for equivalent events. False aggressive memories were all too easy to implant, particularly in the minds of individuals with a proclivity towards aggression. Once implanted, the false memories were indistinguishable from true memories for the same events, on several dimensions, including emotional content. Implications for aggression-related memory more generally as well as false confessions are discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Reactions to abortion and subsequent mental health.

    PubMed

    Fergusson, David M; Horwood, L John; Boden, Joseph M

    2009-11-01

    There has been continued interest in the extent to which women have positive and negative reactions to abortion. To document emotional reactions to abortion, and to examine the links between reactions to abortion and subsequent mental health outcomes. Data were gathered on the pregnancy and mental health history of a birth cohort of over 500 women studied to the age of 30. Abortion was associated with high rates of both positive and negative emotional reactions; however, nearly 90% of respondents believed that the abortion was the right decision. Analyses showed that the number of negative responses to the abortion was associated with increased levels of subsequent mental health disorders (P<0.05). Further analyses suggested that, after adjustment for confounding, those having an abortion and reporting negative reactions had rates of mental health disorders that were approximately 1.4-1.8 times higher than those not having an abortion. Abortion was associated with both positive and negative emotional reactions. The extent of negative emotional reactions appeared to modify the links between abortion and subsequent mental health problems.

  17. A case of placental trisomy 18 mosaicism causing a false negative NIPT result.

    PubMed

    Yang, Jiexia; Qi, Yiming; Guo, Fangfang; Hou, Yaping; Peng, Haishan; Wang, Dongmei; Oy, Haoxin; Yin, Aihua

    2017-01-01

    The non-invasive prenatal testing that evaluates circulating cell free DNA, and has been established as an additional pregnancy test for detecting the common fetal trisomies 21, 18 and 13 is rapidly revolutionizing prenatal screening as a result of its increased sensitivity and specificity. However, false positive and false negative results still exist. We presented a case in which the non-invasive prenatal testing results were normal at 15 gestational age (GA), but an ultrasound examination at 30GA showed that the fetus had heart abnormalities, and the third trimester ultrasound at 33GA noted multiple anomalies including a 3.0 mm ventricular septal defect. Along with cordocentesis at 33GA, the cord blood sample cytogenetics analysis showed a mos 47,XN,+18[61]/46,XN[39] T18 karyotype. Six placental biopsies confirmed that the chromosome 18 placenta chimerism ratio had changed from 33% to 72%. Ultimately, the pregnancy was interrupted at 34GA. We presented this case to highlight the need to clearly explain false positive or false negative results to patients. We believe that this information will also influence the development of future diagnostic test methodologies.

  18. 40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction product of alkane-diol and... Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical... as reaction product of alkanediol and epichlorohydrin (PMN P-89-760) is subject to reporting under...

  19. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Dimer acid/rosin amidoamine reaction... Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... generically as Dimer acid/rosin amidoamine reaction product (PMN P-99-0143) is subject to reporting under this...

  20. 40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction product of alkane-diol and... Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical... as reaction product of alkanediol and epichlorohydrin (PMN P-89-760) is subject to reporting under...

  1. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluoric acid, reaction products... New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... identified generically as a hydrofluoric acid, reaction products with octane (PMN P-99-0052) is subject to...

  2. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluoric acid, reaction products... New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... identified generically as a hydrofluoric acid, reaction products with octane (PMN P-99-0052) is subject to...

  3. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Dimer acid/rosin amidoamine reaction... Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... generically as Dimer acid/rosin amidoamine reaction product (PMN P-99-0143) is subject to reporting under this...

  4. 40 CFR 721.10212 - 1,2-Ethanediol, reaction products with epichlorohydrin.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false 1,2-Ethanediol, reaction products with... Specific Chemical Substances § 721.10212 1,2-Ethanediol, reaction products with epichlorohydrin. (a... 1,2-ethanediol, reaction products with epichlorohydrin (PMN P-09-241; CAS No. 705265-31-2) is...

  5. Hybrid capacitors utilizing halogen-based redox reactions at interface between carbon positive electrode and aqueous electrolytes

    NASA Astrophysics Data System (ADS)

    Yamazaki, Shigeaki; Ito, Tatsuya; Murakumo, Yuka; Naitou, Masashi; Shimooka, Toshiharu; Yamagata, Masaki; Ishikawa, Masashi

    2016-09-01

    We propose novel hybrid capacitors (HCs) with electrolyte-involved redox reactions of bromide or iodide species by pretreatment of an activated carbon positive electrode. The treatment is simple; impregnation of pores at an activated carbon fiber cloth (ACFC) as a positive electrode with bromine- or iodine-containing water before cell assembly. The treated positive electrode is applied to a HC cell with a non-treated negative electrode of ACFC and its electrochemical performance is investigated by galvanostatic cycling and leakage current tests. Few studies on such "electrolytic" charge storage systems have provided acceptable capacitor performance because of inevitable self-discharge caused by diffusion of charged species form an electrode to the other one through an electrolyte. Nevertheless, our electrolyte-redox-based HCs show excellent performance without undesirable diffusion of charged species. Moreover, the present HC utilizing a bromide redox system fulfills a practical cell voltage of 1.8 V in spite of an aqueous electrolyte system. This high voltage provides excellent energy density, which is 5 times higher than that in a conventional aqueous electric double-layer capacitor (EDLC), and 1.2 times higher even than that in a 2.7 V-class non-aqueous EDLC, while keeping high charge-discharge rate capability.

  6. Developmental Aspects of Reaction to Positive Inducements

    ERIC Educational Resources Information Center

    Lindskold, Svenn; And Others

    1970-01-01

    Probes children's behavioral sensitivity to variation in reward probability and magnitude (bribes) and suggests that preadolescent children do respond to promises of positive inducements for cooperation in a mixed-motive situation. (WY)

  7. 21 CFR 73.3127 - Vinyl alcohol/methyl methacrylate-dye reaction products.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Vinyl alcohol/methyl methacrylate-dye reaction... Vinyl alcohol/methyl methacrylate-dye reaction products. (a) Identity. The color additives are formed by... methacrylate-dye reaction product listed under this section into commerce shall submit to the Food and Drug...

  8. 21 CFR 73.3127 - Vinyl alcohol/methyl methacrylate-dye reaction products.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Vinyl alcohol/methyl methacrylate-dye reaction... Vinyl alcohol/methyl methacrylate-dye reaction products. (a) Identity. The color additives are formed by... methacrylate-dye reaction product listed under this section into commerce shall submit to the Food and Drug...

  9. Impact of false-negative sentinel lymph node biopsy on survival in patients with cutaneous melanoma.

    PubMed

    Caracò, C; Marone, U; Celentano, E; Botti, G; Mozzillo, N

    2007-09-01

    Sentinel lymph node biopsy is widely accepted as standard care in melanoma despite lack of pertinent randomized trials results. A possible pitfall of this procedure is the inaccurate identification of the sentinel lymph node leading to biopsy and analysis of a nonsentinel node. Such a technical failure may yield a different prognosis. The purpose of this study is to analyze the incidence of false negativity and its impact on clinical outcome and to try to understand its causes. The Melanoma Data Base at National Cancer Institute of Naples was analyzed comparing results between false-negative and tumor-positive sentinel node patients focusing on overall survival and prognostic factors influencing the clinical outcome. One hundred fifty-one cases were diagnosed to be tumor-positive after sentinel lymph node biopsy and were subjected to complete lymph node dissection. Thirty-four (18.4%)patients with tumor-negative sentinel node subsequently developed lymph node metastases in the basin site of the sentinel procedure. With a median follow-up of 42.8 months the 5-year overall survival was 48.4% and 66.3% for false-negative and tumor-positive group respectively with significant statistical differences (P < .03). The sensitivity of sentinel lymph node biopsy was 81.6%, and a regional nodal basin recurrence after negative-sentinel node biopsy means a worse prognosis, compared with patients submitted to complete lymph node dissection after a positive sentinel biopsy. The evidence of higher number of tumor-positive nodes after delayed lymphadenectomy in false-negative group compared with tumor-positive sentinel node cases, confirmed the importance of an early staging of lymph nodal involvement. Further data will better clarify the role of prognostic factors to identify cases with a more aggressive biological behavior of the disease.

  10. Gale Crater - False Color

    NASA Image and Video Library

    2017-02-15

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. Today's false color image shows part of Gale Crater. Basaltic sands are dark blue in this type of false color combination. The Curiosity Rover is located in another portion of Gale Crater, far southwest of this image. Orbit Number: 51803 Latitude: -4.39948 Longitude: 138.116 Instrument: VIS Captured: 2013-08-18 09:04 http://photojournal.jpl.nasa.gov/catalog/PIA21312

  11. Stress and emotional valence effects on children's versus adolescents' true and false memory.

    PubMed

    Quas, Jodi A; Rush, Elizabeth B; Yim, Ilona S; Edelstein, Robin S; Otgaar, Henry; Smeets, Tom

    2016-01-01

    Despite considerable interest in understanding how stress influences memory accuracy and errors, particularly in children, methodological limitations have made it difficult to examine the effects of stress independent of the effects of the emotional valence of to-be-remembered information in developmental populations. In this study, we manipulated stress levels in 7-8- and 12-14-year-olds and then exposed them to negative, neutral, and positive word lists. Shortly afterward, we tested their recognition memory for the words and false memory for non-presented but related words. Adolescents in the high-stress condition were more accurate than those in the low-stress condition, while children's accuracy did not differ across stress conditions. Also, among adolescents, accuracy and errors were higher for the negative than positive words, while in children, word valence was unrelated to accuracy. Finally, increases in children's and adolescents' cortisol responses, especially in the high-stress condition, were related to greater accuracy but not false memories and only for positive emotional words. Findings suggest that stress at encoding, as well as the emotional content of to-be-remembered information, may influence memory in different ways across development, highlighting the need for greater complexity in existing models of true and false memory formation.

  12. Social influence and mental routes to the production of authentic false memories and inauthentic false memories.

    PubMed

    Wagner, Michael F; Skowronski, John J

    2017-05-01

    Two studies assessed the extent to which people incorporated false facts provided by bogus others into their own recognition memory reports, and how these false memory reports were affected by: (a) truth of the information in others' summaries supporting the false facts, (b) motivation to process stories and summaries, (c) source credibility, and (d) ease of remembering original facts. False memory report frequency increased when false facts in a summary were supported by true information and varied inversely with the ease with which original facts could be remembered. Results from a measure probing participants' memory perceptions suggest that some false memories are authentic: People sometimes lack awareness of both the incorporation of false facts into their memory reports and where the false facts came from. However, many false memories are inauthentic: Despite reporting a false memory, people sometimes retain knowledge of the original stimulus and/or the origin of false facts. Copyright © 2017. Published by Elsevier Inc.

  13. Stress and anxiety effects on positive skin test responses in young adults with allergic rhinitis.

    PubMed

    Heffner, Kathi L; Kiecolt-Glaser, Janice K; Glaser, Ronald; Malarkey, William B; Marshall, Gailen D

    2014-07-01

    Anxiety and psychological stress affect allergy-related immune function. How these relations influence the evaluations of patients with allergic rhinitis is unknown. To examine whether anxiety and stress exposure affect skin prick test (SPT) responses to common allergens for which patients with atopy showed no prior positive SPT response. Patients with allergic rhinitis, evidenced by clinical history and SPT results, were admitted twice to a hospital research unit for 4 hours. In a crossover design, SPT wheals were assessed before and after the Trier Social Stress Test and then the following morning; for comparison, SPT wheals were assessed before and after a laboratory session without a stressor. Analyses focused on wheal responses for common allergens that tested negative (wheal size <3 mm larger than saline) from SPTs performed at multiple baseline assessments. After the Trier Social Stress Test, more anxious patients with atopy had a higher incidence of positive SPT reactions to antigens that previously tested negative. Anxiety was unrelated to positive SPT incidence under nonstressful conditions. Based on clinical symptom reports, newly positive SPT reactions after the stressor were apparently corrections of previously false-negative SPT reactions. The SPT wheal responses for allergens previously testing negative were enhanced after a stressor. Histamine (positive control) or saline (negative control) SPT responses were not affected. A laboratory stressor affected allergen SPT responses in more anxious patients with allergic rhinitis. In addition to clinical history, assessment of anxiety and current stress at the time of the SPT may provide valuable information about a patient's allergic status and aid in clinical decision making. Copyright © 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  14. 19 CFR 11.13 - False designations of origin and false descriptions; false marking of articles of gold or silver.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... descriptions; false marking of articles of gold or silver. 11.13 Section 11.13 Customs Duties U.S. CUSTOMS AND... gold or silver. (a) Articles which bear, or the containers which bear, false designations of origin, or.... 1405q, and shall be detained. (b) Articles made in whole or in part of gold or silver or alloys thereof...

  15. 19 CFR 11.13 - False designations of origin and false descriptions; false marking of articles of gold or silver.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... descriptions; false marking of articles of gold or silver. 11.13 Section 11.13 Customs Duties U.S. CUSTOMS AND... gold or silver. (a) Articles which bear, or the containers which bear, false designations of origin, or.... 1405q, and shall be detained. (b) Articles made in whole or in part of gold or silver or alloys thereof...

  16. 19 CFR 11.13 - False designations of origin and false descriptions; false marking of articles of gold or silver.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... descriptions; false marking of articles of gold or silver. 11.13 Section 11.13 Customs Duties U.S. CUSTOMS AND... gold or silver. (a) Articles which bear, or the containers which bear, false designations of origin, or.... 1405q, and shall be detained. (b) Articles made in whole or in part of gold or silver or alloys thereof...

  17. 19 CFR 11.13 - False designations of origin and false descriptions; false marking of articles of gold or silver.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... descriptions; false marking of articles of gold or silver. 11.13 Section 11.13 Customs Duties U.S. CUSTOMS AND... gold or silver. (a) Articles which bear, or the containers which bear, false designations of origin, or.... 1405q, and shall be detained. (b) Articles made in whole or in part of gold or silver or alloys thereof...

  18. 19 CFR 11.13 - False designations of origin and false descriptions; false marking of articles of gold or silver.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... descriptions; false marking of articles of gold or silver. 11.13 Section 11.13 Customs Duties U.S. CUSTOMS AND... gold or silver. (a) Articles which bear, or the containers which bear, false designations of origin, or.... 1405q, and shall be detained. (b) Articles made in whole or in part of gold or silver or alloys thereof...

  19. Level of visual acuity necessary to avoid false-positives on the HRR and Ishihara color vision tests.

    PubMed

    Ng, Jason S; Shih, Brian

    2017-05-11

    Minimizing false-positives (FPs) when evaluating color vision is important in eye care. Identification of plate 1 (demonstration plate) is often considered a way to avoid FPs. However, few studies have quantified the minimum level of visual acuity (VA) that would minimize FPs for the Ishihara and HRR color tests. Threshold levels of optical defocus were obtained from 25 color normal subjects. Blur levels were obtained for Ishihara (38 plate) plates 1, 10, and 15 and 4th edition HRR plates 1, 7, 10, and 20 using the method of limits. Corresponding VAs were measured through these blur levels at 40 centimeters after adjusting for the dioptric distance difference. Analysis of variance testing was used to analyze the data. Mean optical defocus values in diopters (mean ± SD) for HRR plates 1, 7, 10, and 20 were 6.23 ± 1.61, 1.23 ± 1.16, 2.41 ± 1.31, and 7.96 ± 2.03, respectively, and for Ishihara plates 1, 10, and 15 were 5.70 ± 1.52, 3.68 ± 1.71, and 4.62 ± 1.56, respectively. There was a significant difference between the screening and demonstration plates for both tests (p<0.001). Based on the plate in each test that was found to be the least tolerant to blur, the average minimum VAs needed to identify the screening plates were approximately 20/180 for the Ishihara test and 20/50 for the HRR test. Identifying the demonstration plate in the Ishihara and HRR tests does not ensure FPs will be avoided.

  20. Adaptive false memory: Imagining future scenarios increases false memories in the DRM paradigm.

    PubMed

    Dewhurst, Stephen A; Anderson, Rachel J; Grace, Lydia; van Esch, Lotte

    2016-10-01

    Previous research has shown that rating words for their relevance to a future scenario enhances memory for those words. The current study investigated the effect of future thinking on false memory using the Deese/Roediger-McDermott (DRM) procedure. In Experiment 1, participants rated words from 6 DRM lists for relevance to a past or future event (with or without planning) or in terms of pleasantness. In a surprise recall test, levels of correct recall did not vary between the rating tasks, but the future rating conditions led to significantly higher levels of false recall than the past and pleasantness conditions did. Experiment 2 found that future rating led to higher levels of false recognition than did past and pleasantness ratings but did not affect correct recognition. The effect in false recognition was, however, eliminated when DRM items were presented in random order. Participants in Experiment 3 were presented with both DRM lists and lists of unrelated words. Future rating increased levels of false recognition for DRM lures but did not affect correct recognition for DRM or unrelated lists. The findings are discussed in terms of the view that false memories can be associated with adaptive memory functions.

  1. True and false recall and dissociation among maltreated children: the role of self-schema.

    PubMed

    Valentino, Kristin; Cicchetti, Dante; Rogosch, Fred A; Toth, Sheree L

    2008-01-01

    The current investigation addresses the manner through which trauma affects basic memory and self-system processes. True and false recall for self-referent stimuli were assessed in conjunction with dissociative symptomatology among abused (N=76), neglected (N=92), and nonmaltreated (N=116) school-aged children. Abused, neglected, and nonmaltreated children did not differ in the level of processing self-schema effect or in the occurrence and frequency of false recall. Rather, differences in the affective valence of false recall emerged as a function of maltreatment subtype and age. Regarding dissociation, the abused children displayed higher levels of dissociative symptomatology than did the nonmaltreated children. Although abused, neglected, and nonmaltreated children did not exhibit differences in the valence of their self-schemas, positive and negative self-schemas were related to self-integration differently among the subgroups of maltreatment. Negative self-schemas were associated with increased dissociation among the abused children, whereas positive self-schemas were related to increased dissociation for the neglected children. Thus, positive self-schemas displayed by the younger neglected children were related to higher dissociation, suggestive of defensive self-processing. Implications for clinical intervention are underscored.

  2. Recognition of lesion correspondence on two mammographic views: a new method of false-positive reduction for computerized mass detection

    NASA Astrophysics Data System (ADS)

    Sahiner, Berkman; Petrick, Nicholas; Chan, Heang-Ping; Paquerault, Sophie; Helvie, Mark A.; Hadjiiski, Lubomir M.

    2001-07-01

    We used the correspondence of detected structures on two views of the same breast for false-positive (FP) reduction in computerized detection of mammographic masses. For each initially detected object on one view, we considered all possible pairings with objects on the other view that fell within a radial band defined by the nipple-to-object distances. We designed a 'correspondence classifier' to classify these pairs as either the same mass (a TP-TP pair) or a mismatch (a TP-FP, FP-TP or FP-FP pair). For each pair, similarity measures of morphological and texture features were derived and used as input features in the correspondence classifier. Two-view mammograms from 94 cases were used as a preliminary data set. Initial detection provided 6.3 FPs/image at 96% sensitivity. Further FP reduction in single view resulted in 1.9 FPs/image at 80% sensitivity and 1.1 FPs/image at 70% sensitivity. By combining single-view detection with the correspondence classifier, detection accuracy improved to 1.5 FPs/image at 80% sensitivity and 0.7 FPs/image at 70% sensitivity. Our preliminary results indicate that the correspondence of geometric, morphological, and textural features of a mass on two different views provides valuable additional information for reducing FPs.

  3. Melas Chasma - False Color

    NASA Image and Video Library

    2017-07-13

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. Today's false color image shows part of Melas Chasma. Orbit Number: 59750 Latitude: -10.5452 Longitude: 290.307 Instrument: VIS Captured: 2015-06-03 12:33 https://photojournal.jpl.nasa.gov/catalog/PIA21705

  4. Melas Chasma - False Color

    NASA Image and Video Library

    2015-08-21

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. Today's false color image shows part of Melas Chasma. Orbit Number: 10289 Latitude: -9.9472 Longitude: 285.933 Instrument: VIS Captured: 2004-04-09 12:43 http://photojournal.jpl.nasa.gov/catalog/PIA19756

  5. Young Adolescents' Responses to Positive Events: Associations with Positive Affect and Adjustment

    ERIC Educational Resources Information Center

    Gentzler, Amy L.; Morey, Jennifer N.; Palmer, Cara A.; Yi, Chit Yuen

    2013-01-01

    This study examined how maximizing and minimizing responses to positive events were associated with sustained positive feelings about the events and adjustment in a community sample of 56 young adolescents (31 boys and 25 girls, 10-14 years of age). On daily reports, adolescents reported their positive emotional reactions to their best event each…

  6. Conditional reasoning with false premises facilitates the transition between familiar and abstract reasoning.

    PubMed

    Markovits, Henry; Lortie-Forgues, Hugues

    2011-01-01

    Abstract reasoning is critical for science and mathematics, but is very difficult. In 3 studies, the hypothesis that alternatives generation required for conditional reasoning with false premises facilitates abstract reasoning is examined. Study 1 (n = 372) found that reasoning with false premises improved abstract reasoning in 12- to 15-year-olds. Study 2 (n = 366) found a positive effect of simply generating alternatives, but only in 19-year-olds. Study 3 (n = 92) found that 9- to 11-year-olds were able to respond logically with false premises, whereas no such ability was observed in 6- to 7-year-olds. Reasoning with false premises was found to improve reasoning with semiabstract premises in the older children. These results support the idea that alternatives generation with false premises facilitates abstract reasoning. © 2011 The Authors. Child Development © 2011 Society for Research in Child Development, Inc.

  7. Method for predicting enzyme-catalyzed reactions

    DOEpatents

    Hlavacek, William S.; Unkefer, Clifford J.; Mu, Fangping; Unkefer, Pat J.

    2013-03-19

    The reactivity of given metabolites is assessed using selected empirical atomic properties in the potential reaction center. Metabolic reactions are represented as biotransformation rules. These rules are generalized from the patterns in reactions. These patterns are not unique to reactants but are widely distributed among metabolites. Using a metabolite database, potential substructures are identified in the metabolites for a given biotransformation. These substructures are divided into reactants or non-reactants, depending on whether they participate in the biotransformation or not. Each potential substructure is then modeled using descriptors of the topological and electronic properties of atoms in the potential reaction center; molecular properties can also be used. A Support Vector Machine (SVM) or classifier is trained to classify a potential reactant as a true or false reactant using these properties.

  8. Terra Cimmeria - False Color

    NASA Image and Video Library

    2016-10-11

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. Today's false color image shows dust devil tracks (dark blue linear feature) in Terra Cimmeria. Orbit Number: 43463 Latitude: -53.1551 Longitude: 125.069 Instrument: VIS Captured: 2011-10-01 23:55 http://photojournal.jpl.nasa.gov/catalog/PIA21009

  9. Russell Crater - False Color

    NASA Image and Video Library

    2017-06-01

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. Today's false color image shows part of Russell Crater in Noachis Terra. Orbit Number: 59591 Latitude: -54.471 Longitude: 13.1288 Instrument: VIS Captured: 2015-05-21 10:57 https://photojournal.jpl.nasa.gov/catalog/PIA21674

  10. A Luenberger observer for reaction-diffusion models with front position data

    NASA Astrophysics Data System (ADS)

    Collin, Annabelle; Chapelle, Dominique; Moireau, Philippe

    2015-11-01

    We propose a Luenberger observer for reaction-diffusion models with propagating front features, and for data associated with the location of the front over time. Such models are considered in various application fields, such as electrophysiology, wild-land fire propagation and tumor growth modeling. Drawing our inspiration from image processing methods, we start by proposing an observer for the eikonal-curvature equation that can be derived from the reaction-diffusion model by an asymptotic expansion. We then carry over this observer to the underlying reaction-diffusion equation by an ;inverse asymptotic analysis;, and we show that the associated correction in the dynamics has a stabilizing effect for the linearized estimation error. We also discuss the extension to joint state-parameter estimation by using the earlier-proposed ROUKF strategy. We then illustrate and assess our proposed observer method with test problems pertaining to electrophysiology modeling, including with a realistic model of cardiac atria. Our numerical trials show that state estimation is directly very effective with the proposed Luenberger observer, while specific strategies are needed to accurately perform parameter estimation - as is usual with Kalman filtering used in a nonlinear setting - and we demonstrate two such successful strategies.

  11. False feedback and beliefs influence name recall in younger and older adults.

    PubMed

    Strickland-Hughes, Carla M; West, Robin Lea; Smith, Kimberly A; Ebner, Natalie C

    2017-09-01

    Feedback is an important self-regulatory process that affects task effort and subsequent performance. Benefits of positive feedback for list recall have been explored in research on goals and feedback, but the effect of negative feedback on memory has rarely been studied. The current research extends knowledge of memory and feedback effects by investigating face-name association memory and by examining the potential mediation of feedback effects, in younger and older adults, through self-evaluative beliefs. Beliefs were assessed before and after name recognition and name recall testing. Repeated presentation of false positive feedback was compared to false negative feedback and a no feedback condition. Results showed that memory self-efficacy declined over time for participants in the negative and no feedback conditions but was sustained for those receiving positive feedback. Furthermore, participants who received negative feedback felt older after testing than before testing. For name recall, the positive feedback group outperformed the negative feedback and no feedback groups combined, with no age interactions. The observed feedback-related effects on memory were fully mediated by changes in memory self-efficacy. These findings advance our understanding of how beliefs are related to feedback in memory and inform future studies examining the importance of self-regulation in memory.

  12. Negative affect promotes encoding of and memory for details at the expense of the gist: affect, encoding, and false memories.

    PubMed

    Storbeck, Justin

    2013-01-01

    I investigated whether negative affective states enhance encoding of and memory for item-specific information reducing false memories. Positive, negative, and neutral moods were induced, and participants then completed a Deese-Roediger-McDermott (DRM) false-memory task. List items were presented in unique spatial locations or unique fonts to serve as measures for item-specific encoding. The negative mood conditions had more accurate memories for item-specific information, and they also had fewer false memories. The final experiment used a manipulation that drew attention to distinctive information, which aided learning for DRM words, but also promoted item-specific encoding. For the condition that promoted item-specific encoding, false memories were reduced for positive and neutral mood conditions to a rate similar to that of the negative mood condition. These experiments demonstrated that negative affective cues promote item-specific processing reducing false memories. People in positive and negative moods encode events differently creating different memories for the same event.

  13. 40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Reaction products of substituted... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9300 Reaction products of... significant new uses subject to reporting. (1) The chemical substance identified generically as reaction...

  14. 40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Reaction products of substituted... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9300 Reaction products of... significant new uses subject to reporting. (1) The chemical substance identified generically as reaction...

  15. 40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Reaction products of substituted... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9300 Reaction products of... significant new uses subject to reporting. (1) The chemical substance identified generically as reaction...

  16. 40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction products of substituted... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9300 Reaction products of... significant new uses subject to reporting. (1) The chemical substance identified generically as reaction...

  17. 40 CFR 721.10211 - Octadecanoic acid, reaction products with diethylenetriamine and urea, acetates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Octadecanoic acid, reaction products... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10211 Octadecanoic acid, reaction... subject to reporting. (1) The chemical substance identified as octadecanoic acid, reaction products with...

  18. 40 CFR 721.9300 - Reaction products of substituted hydroxy-alkanes and polyalkylpolyisocyanatocarbomono- cycle.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction products of substituted... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9300 Reaction products of... significant new uses subject to reporting. (1) The chemical substance identified generically as reaction...

  19. 40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Ethyl silicate, reaction products with... Significant New Uses for Specific Chemical Substances § 721.9514 Ethyl silicate, reaction products with.... (1) The chemical substance identified generically as Ethyl silicate, reaction products with modified...

  20. 40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Ethyl silicate, reaction products with... Significant New Uses for Specific Chemical Substances § 721.9514 Ethyl silicate, reaction products with.... (1) The chemical substance identified generically as Ethyl silicate, reaction products with modified...

  1. Frequency of positive patch test reactions to preservatives: The Australian experience.

    PubMed

    Chow, Elizabeth T; Avolio, Andrea M; Lee, Adriene; Nixon, Rosemary

    2013-02-01

    Preservatives are important causes of allergic contact dermatitis. The frequency of allergy to preservatives in Australia has been unknown to date. Our objectives are to report the frequency of positive preservative patch test reactions in Australia, comparing them to the published international data, as well as exploring the current regulations in place for preservative use in Australia. This was the first retrospective study of patch testing results, aggregated from four patch test clinics in three centres in Melbourne and Sydney. In all, 6845 patients were patch-tested during 1993-2006 and in this period the five most frequent preservative allergens were formaldehyde (4.6%), Euxyl K400 (containing methyldibromo glutaronitrile and phenoxyethanol) (3.3%), quaternium-15 (2.9%), diazolidinyl urea (2.4%), and methylchloroisothiazolinone/methylisothiazolinone (2.3%). These were followed by dimethylol dimethyl DMDM hydantoin (2.1%), chloroacetamide (2.1%) and imidazolidinyl urea (1.9%). The least frequent sensitisers were parabens (1.1%), 2-bromo-2-nitropropane-1, 3-diol (0.9%) and benzyl alcohol (0.4%). Formaldehyde was the most prevalent preservative allergen. Chloroacetamide allergy was more commonly seen in Australia. Parabens, 2-bromo-2-nitropropane-1,3-diol and benzyl alcohol were the least frequent sensitisers. Household products in Australia are not required to list all ingredients preventing sensitised individuals from properly assessing their exposure. © 2012 The Authors Australasian Journal of Dermatology © 2012 The Australasian College of Dermatologists.

  2. Makhambet Crater - False Color

    NASA Image and Video Library

    2015-01-29

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows Makhambet Crater.

  3. Emotional content enhances true but not false memory for categorized stimuli.

    PubMed

    Choi, Hae-Yoon; Kensinger, Elizabeth A; Rajaram, Suparna

    2013-04-01

    Past research has shown that emotion enhances true memory, but that emotion can either increase or decrease false memory. Two theoretical possibilities-the distinctiveness of emotional stimuli and the conceptual relatedness of emotional content-have been implicated as being responsible for influencing both true and false memory for emotional content. In the present study, we sought to identify the mechanisms that underlie these mixed findings by equating the thematic relatedness of the study materials across each type of valence used (negative, positive, or neutral). In three experiments, categorically bound stimuli (e.g., funeral, pets, and office items) were used for this purpose. When the encoding task required the processing of thematic relatedness, a significant true-memory enhancement for emotional content emerged in recognition memory, but no emotional boost to false memory (exp. 1). This pattern persisted for true memory with a longer retention interval between study and test (24 h), and false recognition was reduced for emotional items (exp. 2). Finally, better recognition memory for emotional items once again emerged when the encoding task (arousal ratings) required the processing of the emotional aspect of the study items, with no emotional boost to false recognition (EXP. 3). Together, these findings suggest that when emotional and neutral stimuli are equivalently high in thematic relatedness, emotion continues to improve true memory, but it does not override other types of grouping to increase false memory.

  4. Analysis of polyphosphates in fish and shrimps tissues by two different ion chromatography methods: implications on false-negative and -positive findings.

    PubMed

    Kaufmann, A; Maden, K; Leisser, W; Matera, M; Gude, T

    2005-11-01

    Inorganic polyphosphates (di-, tri- and higher polyphosphates) can be used to treat fish, fish fillets and shrimps in order to improve their water-binding capacity. The practical relevance of this treatment is a significant gain of weight caused by the retention/uptake of water and natural juice into the fish tissues. This practice is legal; however, the use of phosphates has to be declared. The routine control testing of fish for the presence of polyphosphates, produced some results that were difficult to explain. One of the two analytical methods used determined low diphosphate concentrations in a number of untreated samples, while the other ion chromatography (IC) method did not detect them. This initiated a number of investigations: results showed that polyphosphates in fish and shrimps tissue undergo a rapid enzymatic degradation, producing the ubiquitous orthophosphate. This led to the conclusion that sensitive analytical methods are required in order to detect previous polyphosphate treatment of a sample. The polyphosphate concentrations detected by one of the analytical methods could not be explained by the degradation of endogenous high-energy nucleotides like ATP into diphosphate, but by a coeluting compound. Further investigations by LC-MS-MS proved that the substance responsible for the observed peak was inosine monophsosphate (IMP) and not as thought the inorganic diphosphate. The method producing the false-positive result was modified and both methods were ultimately able to detect polyphosphates well separated from natural nucleotides. Polyphosphates could no longer be detected (<0.5 mg kg-1) after modification of the analytical methodology. The relevance of these findings lies in the fact that similar analytical methods are employed in various control laboratories, which might lead to false interpretation of measurements.

  5. Coinfection of hepatitis A virus genotype IA and IIIA complicated with autoimmune hemolytic anemia, prolonged cholestasis, and false-positive immunoglobulin M anti-hepatitis E virus: a case report.

    PubMed

    Kim, Hee Sup; Jeong, Sook Hyang; Jang, Je Hyuck; Myung, Hyung Joon; Kim, Jin Wook; Bang, Soo Mee; Song, Sang Hoon; Kim, Haeryoung; Yun, Hae Sun

    2011-12-01

    A 37-year-old male presented with fever and jaundice was diagnosed as hepatitis A complicated with progressive cholestasis and severe autoimmune hemolytic anemia. He was treated with high-dose prednisolone (1.5 mg/kg), and eventually recovered. His initial serum contained genotype IA hepatitis A virus (HAV), which was subsequently replaced by genotype IIIA HAV. Moreover, at the time of development of hemolytic anemia, he became positive for immunoglobulin M (IgM) anti-hepatitis E virus (HEV). We detected HAV antigens in the liver biopsy specimen, while we detected neither HEV antigen in the liver nor HEV RNA in his serum. This is the first report of hepatitis A coinfected with two different genotypes manifesting with autoimmune hemolytic anemia, prolonged cholestasis, and false-positive IgM anti-HEV.

  6. Coinfection of hepatitis A virus genotype IA and IIIA complicated with autoimmune hemolytic anemia, prolonged cholestasis, and false-positive immunoglobulin M anti-hepatitis E virus: a case report

    PubMed Central

    Kim, Hee-Sup; Jang, Je-Hyuck; Myung, Hyung-Joon; Kim, Jin-Wook; Bang, Soo-Mee; Song, Sang Hoon; Kim, Haeryoung; Yun, Hae Sun

    2011-01-01

    A 37-year-old male presented with fever and jaundice was diagnosed as hepatitis A complicated with progressive cholestasis and severe autoimmune hemolytic anemia. He was treated with high-dose prednisolone (1.5 mg/kg), and eventually recovered. His initial serum contained genotype IA hepatitis A virus (HAV), which was subsequently replaced by genotype IIIA HAV. Moreover, at the time of development of hemolytic anemia, he became positive for immunoglobulin M (IgM) anti-hepatitis E virus (HEV). We detected HAV antigens in the liver biopsy specimen, while we detected neither HEV antigen in the liver nor HEV RNA in his serum. This is the first report of hepatitis A coinfected with two different genotypes manifesting with autoimmune hemolytic anemia, prolonged cholestasis, and false-positive IgM anti-HEV. PMID:22310798

  7. Early False-Belief Understanding.

    PubMed

    Scott, Rose M; Baillargeon, Renée

    2017-04-01

    Intense controversy surrounds the question of when children first understand that others can hold false beliefs. Results from traditional tasks suggest that false-belief understanding does not emerge until about 4 years of age and constitutes a major developmental milestone in social cognition. By contrast, results from nontraditional tasks, which have steadily accumulated over the past 10 years, suggest that false-belief understanding is already present in infants (under age 2 years) and toddlers (age 2-3 years) and thus forms an integral part of social cognition from early in life. Here we first present an overview of the findings from nontraditional tasks. We then return to traditional tasks and argue that processing difficulties, rather than limitations in false-belief understanding, account for young children's failure at these tasks. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. False-negative type-specific glycoprotein G antibody responses in STI clinic patients with recurrent HSV-1 or HSV-2 DNA positive genital herpes, The Netherlands.

    PubMed

    van Rooijen, Martijn S; Roest, Wim; Hansen, Gino; Kwa, David; de Vries, Henry J C

    2016-06-01

    Herpes simplex virus (HSV) type-discriminating antibody tests (glycoprotein G (gG) directed) are used to identify naïve persons and differentiate acute infections from recurrences. We studied test characteristics of three commercially available antibody tests in patients with recurrent (established by viral PCR tests) herpes simplex virus type 1 (HSV-1) or herpes simplex virus type 2 (HSV-2) genital herpes episodes. Serum samples (at minimum 3 months after t=0) were examined for the presence of gG-1-specific or gG-2-specific antibodies using the HerpeSelect 1 and 2 Immunoblot IgG, the HerpeSelect 1 and 2 enzyme linked immunoassays IgG and the LIAISON HSV-1 and HSV-2 IgG indirect chemiluminescence immunoassays. The immunoblot was HSV-1 positive in 70.6% (95% CI 44.0% to 89.7%), the LIAISON in 88.2% (95% CI 63.5% to 98.5%) and the ELISA in 82.4% (95% CI 56.6% to 96.2%) of the 17 patients with a recurrent HSV-1 episode. From 33 patients with a recurrent HSV-2 episode, the immunoblot was HSV-2 positive in 84.8% (95% CI 68.1% to 94.9%), the LIAISON in 69.7% (95% CI 51.3% to 84.4%) and the ELISA in 84.8% (95% CI 68.1% to 94.9%). Among 15/17 (88.2%; 95% CI 63.5% to 98.5%) patients with HSV-1 and 30/33 (90.1%; 95% CI 75.7% to 98.1%) patients with HSV-2, HSV-1 or HSV-2 antibodies, respectively, were detected in at least one of the three antibody tests. Commercial type-specific gG HSV-1 or HSV-2 antibody assays were false negative in 12-30% of patients with recurrent HSV-1 or HSV-2 DNA positive genital lesions. The clinical and epidemiological use of type-specific HSV serology can be hampered by false-negative results, especially if based on a single test. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  9. 40 CFR 721.10058 - Reaction product of alkylphenol, aromatic cyclicamine, alkyl diglycidyl dibenzene, and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction product of alkylphenol... Reaction product of alkylphenol, aromatic cyclicamine, alkyl diglycidyl dibenzene, and formaldehyde... identified generically as reaction product of alkylphenol, aromatic cyclicamine, alkyl diglycidyl dibenzene...

  10. 40 CFR 721.10059 - Reaction product of alkylphenyl glycidyl ether, polyalkylenepolyamine, and alkyl diglycidyl...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction product of alkylphenyl... Reaction product of alkylphenyl glycidyl ether, polyalkylenepolyamine, and alkyl diglycidyl dibenzene... identified generically as reaction product of alkylphenyl glycidyl ether, polyalkylenepolyamine, and alkyl...

  11. 40 CFR 721.10059 - Reaction product of alkylphenyl glycidyl ether, polyalkylenepolyamine, and alkyl diglycidyl...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction product of alkylphenyl... Reaction product of alkylphenyl glycidyl ether, polyalkylenepolyamine, and alkyl diglycidyl dibenzene... identified generically as reaction product of alkylphenyl glycidyl ether, polyalkylenepolyamine, and alkyl...

  12. 40 CFR 721.10058 - Reaction product of alkylphenol, aromatic cyclicamine, alkyl diglycidyl dibenzene, and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction product of alkylphenol... Reaction product of alkylphenol, aromatic cyclicamine, alkyl diglycidyl dibenzene, and formaldehyde... identified generically as reaction product of alkylphenol, aromatic cyclicamine, alkyl diglycidyl dibenzene...

  13. Renaudot Crater - False Color

    NASA Image and Video Library

    2015-01-15

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of Renaudot Crater.

  14. Granicus Valles - False Color

    NASA Image and Video Library

    2015-01-12

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of Granicus Valles.

  15. Candor Labes - False Color

    NASA Image and Video Library

    2014-12-25

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of Candor Labes.

  16. Coprates Chasma - False Color

    NASA Image and Video Library

    2015-01-08

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of Coprates Chasma.

  17. Schaeberle Crater - False Color

    NASA Image and Video Library

    2015-01-26

    The THEMIS VIS camera contains 5 filters. The data from different filters can create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of the floor of Schaeberle Crater, including small dunes.

  18. Nili Patera - False Color

    NASA Image and Video Library

    2015-01-02

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of Nili Patera.

  19. Atlantis Chaos - False Color

    NASA Image and Video Library

    2014-12-23

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of Atlantis Chaos.

  20. Coprates Chasma - False Color

    NASA Image and Video Library

    2015-01-01

    The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This false color image from NASA 2001 Mars Odyssey spacecraft shows part of Coprates Chasma.