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Sample records for false positive peptides

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

    Science.gov (United States)

    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.

  2. Correctness of Protein Identifications of Bacillus subtilis Proteome with the Indication on Potential False Positive Peptides Supported by Predictions of Their Retention Times

    Directory of Open Access Journals (Sweden)

    Katarzyna Macur

    2010-01-01

    Full Text Available The predictive capability of the retention time prediction model based on quantitative structure-retention relationships (QSRR was tested. QSRR model was derived with the use of set of peptides identified with the highest scores and originated from 8 known proteins annotated as model ones. The predictive ability of the QSRR model was verified with the use of a Bacillus subtilis proteome digest after separation and identification of the peptides by LC-ESI-MS/MS. That ability was tested with three sets of testing peptides assigned to the proteins identified with different levels of confidence. First, the set of peptides identified with the highest scores achieved in the search were considered. Hence, proteins identified on the basis of more than one peptide were taken into account. Furthermore, proteins identified on the basis of just one peptide were also considered and, depending on the possessed scores, both above and below the assumed threshold, were analyzed in two separated sets. The QSRR approach was applied as the additional constraint in proteomic research verifying results of MS/MS ion search and confirming the correctness of the peptides identifications along with the indication of the potential false positives.

  3. Positive consequences of false memories.

    Science.gov (United States)

    Howe, Mark L; Garner, Sarah R; Patel, Megan

    2013-01-01

    Previous research is replete with examples of the negative consequences of false memories. In the current research, we provide a different perspective on false memories and their development and demonstrate that false memories can have positive consequences. Specifically, we examined the role false memories play in subsequent problem-solving tasks. Children and adults studied and recalled neutral or survival-relevant lists of associated words. They then solved age-normed compound remote associates, some of whose solutions had been primed by false memories created when studying the previous lists. The results showed that regardless of age: (a) survival-related words were not only better recollected but were also more susceptible than neutral words to false memory illusions; and (b) survival-related false memories were better than neutral false memories as primes for problem-solving. These findings are discussed in the context of recent speculation concerning the positive consequences of false memories, and the adaptive nature of reconstructive memory. Copyright © 2013 John Wiley & Sons, Ltd.

  4. False Positive and False Negative Effects on Network Attacks

    Science.gov (United States)

    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.

  5. The positive consequences of false memories

    OpenAIRE

    Howe, M. L.; Garner, S. R.; Patel, M.

    2013-01-01

    Previous research is replete with examples of the negative consequences of false memories. In the current research, we provide a different perspective on false memories and their development and demonstrate that false memories can have positive consequences. Specifically, we examined the role false memories play in subsequent problem-solving tasks. Children and adults studied and recalled neutral or survival-relevant lists of associated words. They then solved age-normed compound remote assoc...

  6. Consequences of false-positive screening mammograms.

    Science.gov (United States)

    Tosteson, Anna N A; Fryback, Dennis G; Hammond, Cristina S; Hanna, Lucy G; Grove, Margaret R; Brown, Mary; Wang, Qianfei; Lindfors, Karen; Pisano, Etta D

    2014-06-01

    False-positive mammograms, a common occurrence in breast cancer screening programs, represent a potential screening harm that is currently being evaluated by the US Preventive Services Task Force. To measure the effect of false-positive mammograms on quality of life by measuring personal anxiety, health utility, and attitudes toward future screening. The Digital Mammographic Imaging Screening Trial (DMIST) quality-of-life substudy telephone survey was performed shortly after screening and 1 year later at 22 DMIST sites and included randomly selected DMIST participants with positive and negative mammograms. Mammogram requiring follow-up testing or referral without a cancer diagnosis. The 6-question short form of the Spielberger State-Trait Anxiety Inventory state scale (STAI-6) and the EuroQol EQ-5D instrument with US scoring. Attitudes toward future screening as measured by women's self-report of future intention to undergo mammographic screening and willingness to travel and stay overnight to undergo a hypothetical new type of mammography that would identify as many cancers with half the false-positive results. Among 1450 eligible women invited to participate, 1226 (84.6%) were enrolled, with follow-up interviews obtained in 1028 (83.8%). Anxiety was significantly higher for women with false-positive mammograms (STAI-6, 35.2 vs 32.7), but health utility scores did not differ and there were no significant differences between groups at 1 year. Future screening intentions differed by group (25.7% vs 14.2% more likely in false-positive vs negative groups); willingness to travel and stay overnight did not (9.9% vs 10.5% in false-positive vs negative groups). Future screening intention was significantly increased among women with false-positive mammograms (odds ratio, 2.12; 95% CI, 1.54-2.93), younger age (2.78; 1.5-5.0), and poorer health (1.63; 1.09-2.43). Women's anticipated high-level anxiety regarding future false-positive mammograms was associated with willingness

  7. An investigation of false positive dosimetry results

    International Nuclear Information System (INIS)

    Lewandowski, M.A.; Davis, S.A.; Goff, T.E.; Wu, C.F.

    1996-01-01

    The Waste Isolation Pilot Plant (WIPP) is a facility designed for the demonstration of the safe disposal of transuranic waste. Currently, the radiation source term is confined to sealed calibration and check sources since WIPP has not received waste for disposal. For several years the WIPP Dosimetry Group has operated a Harshaw Model 8800C reader to analyze Harshaw 8801-7776 thermoluminescent cards (3 TLD-700 and 1 TLD-600) with 8805 holder. The frequency of false positive results for quarterly dosimeter exchanges is higher than desired by the Dosimetry Group management. Initial observations suggested that exposure to intense ambient sunlight may be responsible for the majority of the false positive readings for element 3. A study was designed to investigate the possibility of light leaking through the holder and inducing a signal in element 3. This paper discusses the methods and results obtained, with special emphasis placed on recommendations to reduce the frequency of light-induced false positive readings

  8. Anti-streptavidin IgG antibody interference in anti-cyclic citrullinated peptide (CCP) IgG antibody assays is a rare but important cause of false-positive anti-CCP results.

    Science.gov (United States)

    Berth, Mario; Willaert, Sofie; De Ridder, Carol

    2018-02-21

    The detection of anti-cyclic citrullinated peptide (anti-CCP) IgG antibodies in blood is mainly used for the diagnosis of rheumatoid arthritis. Falsely elevated anti-CCP IgG antibodies due to anti-streptavidin IgG antibodies were suspected in our laboratory. In this study, we evaluated, in a standardized approach, the prevalence of anti-streptavidin IgG antibodies in a primary care setting and the effect of anti-streptavidin IgG antibodies on anti-CCP IgG assays from three different important commercial manufacturers (Abbott, Roche Diagnostics, Thermo Fisher Scientific). Three different populations were consecutively and prospectively studied: serum samples from 1000 ambulatory patients, 286 serum samples from patients for which anti-CCP was requested and 89 serum samples from patients which had previously given a positive anti-CCP result on Architect® i2000. The frequency of confirmed anti-streptavidin IgG-positive samples detected in this study was 0.6% (8/1375). Anti-CCP IgG was determined on the eight samples with confirmed anti-streptavidin IgG antibodies: with the Cobas® method, seven positive anti-CCP results were observed and five positive anti-CCP results with the Architect® method. No positive anti-CCP IgG results were obtained with the EliA™ method. Rheumatoid factor was negative in these eight samples. Anti-streptavidin IgG antibodies rarely cause false-positive results in some anti-CCP assays. However, despite being an infrequent assay problem, it could possibly lead to diagnostic confusion or even an incorrect diagnosis of rheumatoid arthritis.

  9. False positive acetaminophen concentrations in icteric serum

    Directory of Open Access Journals (Sweden)

    L. de Jong

    2016-04-01

    Full Text Available Introduction: Serum concentrations of acetaminophen are measured to predict the risk of hepatotoxicity in cases of acetaminophen overdose and to identify acetaminophen use in patients with acute liver injury without a known cause. The acetaminophen concentration determines if treatment with N-acetyl cysteine, the antidote for acetaminophen poisoning, is warranted. Description: A 49-year-old woman was admitted to our hospital with a hepatic encephalopathy and a total serum bilirubin concentration of 442 µmol/l. The acetaminophen concentration of 11.5 mg/l was measured with an enzymatic-colorimetric assay, thus treatment with N-acetyl cysteine was started. Interestingly, the acetaminophen concentration remained unchanged (11.5–12.3 mg/l during a period of 4 consecutive days. In contrast, the acetaminophen concentration measured by HPLC, a chromatographic technique, remained undetectable Discussion: In the presented case, elevated bilirubin was the most likely candidate to interfere with acetaminophen assay causing false positive results. Bilirubin has intense absorbance in the ultraviolet and visible regions of the electromagnetic spectrum and for that reason it causes interference in an enzymatic-colorimetric assay. Conclusion: False positive acetaminophen laboratory test results may be found in icteric serum, when enzymatic-colorimetric assays are used for determination of an acetaminophen concentration. Questionable acetaminophen results in icteric serum should be confirmed by a non-enzymatic method, by means of ultrafiltration of the serum, or by dilution studies. Keywords: Acetaminophen, Enzymatic-colorimetric assays, HPLC, Bilirubin, Interference, Paracetamol, Liver failure, Jaundice

  10. Analysis of false positive and false negative cytological diagnosis of breast lesions

    International Nuclear Information System (INIS)

    Jamal, Awtif A.; Mansoor, I.

    2001-01-01

    To study the reasons for interpretive errors in false negative and false positive diagnosis of breast carcinoma on fine needle aspiration cytology material. We reviewed only those cases in which cytohistological discrepancies were found, where the cytologic material was abnormal and to some extent misinterpreted or both. There was only one false negative case (false negative fraction 0.32%) proved histologically as ductal carcinoma and four false positive cases (false positive fraction 1.2%); 2 fibroadenoma; 1 fibrocystic disease; and 1 stromal fibrosis. Smears of the two false positive fibroadenoma cases showed very high cellularity, overcrowded clusters and frequent stripped nuclei. The fibrocystic case showed tight clusters of apocrine cells and sheets of loosely aggregated macrophages that were over interpreted. Smears of the false negative ductal carcinoma was hypocellular overall, and the cells showed minimal nuclear pleomorphism. Overcrowded clusters and hypercellular smears should be carefully assessed for uniformity of cells and detailed nuclear and cytomorphological features. If the full-blown malignant cytomorphological changes are not visible, a diagnosis of suspicious or inconclusive should be made and frozen section recommended before surgery. Hypocellularity and relatively nuclear monomorphism are the reasons for failure to diagnose malignant breast lesions. Careful attention should be paid to extreme nuclear monomorphism and absence of naked bipolar cells. A cytologically atypical or suspicious diagnosis together with positive radiological and clinical findings should suggest a diagnosis of malignancy. (author)

  11. Consequences of a false-positive mammography result

    DEFF Research Database (Denmark)

    von Euler-Chelpin, My; Bæksted, Christina; Vejborg, Ilse

    2016-01-01

    Background: Previous research showed women experiencing false-positive mammograms to have greater anxiety about breast cancer than women with normal mammograms. To elucidate psychological effects of false-positive mammograms, we studied impact on drug intake.  Methods: We calculated the ratio...... of drug use for women with false-positive versus women with normal mammograms, before and after the event, using population-based registers, 1997-2006. The ratio of the ratios (RRR) assessed the impact.  Results: Before the test, 40.3% of women from the false-positive group versus 36.2% from the normal...... group used anxiolytic and antidepressant drugs. There was no difference in use of beta blockers. Hormone therapy was used more frequently by the false-positive, 36.6% versus 28.7%. The proportion of women using anxiolytic and antidepressant drugs increased with 19% from the before to the after period...

  12. Automated Astrophysical False Positive Analysis of Transiting Planet Signals

    Science.gov (United States)

    Morton, Timothy

    2015-08-01

    Beginning with Kepler, but continuing with K2 and TESS, transiting planet candidates are now found at a much faster rate than follow-up observations can be obtained. Thus, distinguishing true planet candidates from astrophysical false positives has become primarily a statistical exercise. I will describe a new publicly available open-source Python package for analyzing the astrophysical false positive probabilities of transiting exoplanet signals. In addition, I will present results of applying this analysis to both Kepler and K2 planet candidates, resulting in the probabilistic validation of thousands of exoplanets, as well as identifying many likely false positives.

  13. False positive CT findings of parametrial invasion of cervical carcinoma

    International Nuclear Information System (INIS)

    Yoon, Chi Soon; Moon, Ki Ho; Park, Jong Yeon; Lee, Suck Hong; Kim, Byung Soo

    1994-01-01

    To evaluate the causative factors of the false positive CT findings of parametrial invasions of cervial cancer. We analyzed 17 parametria of 14 patients with the diseases staged over IIb on CT, but confirmed to be under stage IIa on pathology. The CT findings were retrospectively reviewed, and compared with pathologic findings. The causes of false positive diagnosis of parametrial invasions on CT were prominent cardinal ligaments (n = 12), vaginal fornix (n = 3), and prominent uterine vessels (n = 2). Familiarity with these CT finding may be helpful in avoiding false positive diagnosis of parametrial invasion in patients with uterine cervical carcinoma

  14. False positive CT findings of parametrial invasion of cervical carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Chi Soon; Moon, Ki Ho; Park, Jong Yeon; Lee, Suck Hong; Kim, Byung Soo [College of Medicine, Pusan National University, Busan (Korea, Republic of)

    1994-02-15

    To evaluate the causative factors of the false positive CT findings of parametrial invasions of cervial cancer. We analyzed 17 parametria of 14 patients with the diseases staged over IIb on CT, but confirmed to be under stage IIa on pathology. The CT findings were retrospectively reviewed, and compared with pathologic findings. The causes of false positive diagnosis of parametrial invasions on CT were prominent cardinal ligaments (n = 12), vaginal fornix (n = 3), and prominent uterine vessels (n = 2). Familiarity with these CT finding may be helpful in avoiding false positive diagnosis of parametrial invasion in patients with uterine cervical carcinoma.

  15. Epidemiology, public health, and the rhetoric of false positives

    DEFF Research Database (Denmark)

    Blair, Aaron; Saracci, Rodolfo; Vineis, Paolo

    2009-01-01

    BACKGROUND: As an observational science, epidemiology is regarded by some researchers as inherently flawed and open to false results. In a recent paper, Boffetta et al. [Boffetta P, McLaughlin JK, LaVecchia C, Tarone RE, Lipworth L, Blot WJ. False-positive results in cancer epidemiology: a plea f...

  16. False-positive 111In-pentetreotide Uptake in Gastritis

    International Nuclear Information System (INIS)

    Usmani, Sharjeel; Alshammari, Alshaima

    2013-01-01

    111 In-pentetreotide [ 111 In-octreoscan] is the most widely used radiolabeled somatostatin analog for evaluating neuroendocrine tumor overexpression of somatostatin receptors. False-positives studies of somatostatin receptor scintigraphy have been reported and often the cause is unexplained but assumed to be due to high number of somatostatin receptors in other pathologies. Causes of false-positives include visualization of the gallbladder, nasal mucosa and pulmonary hilar areas in respiratory infections, thyroid abnormalities, accessory spleens, recent Cerebrovascular accidents (CVA's) and activity at the site of a recent surgical incision. In infection or inflammation the cause of false-positive uptake is probably the result of tracer binding by somatostatin receptors on the inflammatory leukocytes. In this case report, we report, a 44-year-old male patient with false-positive 111 In-pentetreotide uptake due to gastritis

  17. Characterisation of false-positive observations in botanical surveys

    Directory of Open Access Journals (Sweden)

    Quentin J. Groom

    2017-05-01

    Full Text Available 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

  18. False positive and false negative FDG-PET scans in various thoracic diseases

    International Nuclear Information System (INIS)

    Chang, Jung Min; Lee, Hyun Ju; Goo, Jin Mo; Lee, Ho Young; Lee, Jong Jin; Chung, June Key; Im, Jung Gi

    2006-01-01

    Fluorodeoxygucose (FDG)-positron emission tomography (PET) is being used more and more to differentiate benign form malignant focal lesions and it has been shown to be more efficacious than conventional chest computed tomography (CT). However, FDG is not a cancer-specific agent, and false positive findings in benign diseases have been reported. Infectious diseases (mycobacterial, fungal, bacterial infection), sarcoidosis, radiation pneumonitis and post-operative surgical conditions have shown intense uptake on PET scan. On the other hand, tumors with low glycolytic activity such as adenomas, bronchioloalveolar carcinomas, carcinoid tumors, low grade lymphomas and small sized tumors have revealed false negative findings on PET scan, Furthermore, in diseases located near the physiologic uptake sites (heart, bladder, kidney, and liver), FDG-PET should be complemented with other imaging modalities to confirm results and to minimize false negative findings. Familiarity with these false positive and negative findings will help radiologists interpret PET scans more accurately and also will help to determine the significance of the findings. In this review, we illustrate false positive and negative findings of PET scan in a variety of diseases

  19. 'False-positive' and 'false-negative' test results in clinical urine drug testing.

    Science.gov (United States)

    Reisfield, Gary M; Goldberger, Bruce A; Bertholf, Roger L

    2009-08-01

    The terms 'false-positive' and 'false-negative' are widely used in discussions of urine drug test (UDT) results. These terms are inadequate because they are used in different ways by physicians and laboratory professionals and they are too narrow to encompass the larger universe of potentially misleading, inappropriate and unexpected drug test results. This larger universe, while not solely comprised of technically 'true' or 'false' positive or negative test results, presents comparable interpretive challenges with corresponding clinical implications. In this review, we propose the terms 'potentially inappropriate' positive or negative test results in reference to UDT results that are ambiguous or unexpected and subject to misinterpretation. Causes of potentially inappropriate positive UDT results include in vivo metabolic conversions of a drug, exposure to nonillicit sources of a drug and laboratory error. Causes of potentially inappropriate negative UDT results include limited assay specificity, absence of drug in the urine, presence of drug in the urine, but below established assay cutoff, specimen manipulation and laboratory error. Clinical UDT interpretation is a complicated task requiring knowledge of recent prescription, over-the-counter and herbal drug administration, drug metabolism and analytical sensitivities and specificities.

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

    Science.gov (United States)

    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

  1. Diagnostic Invasiveness and Psychosocial Consequences of False-Positive Mammography

    DEFF Research Database (Denmark)

    Heleno, Bruno M.; Siersma, Volkert Dirk; Brodersen, John

    2015-01-01

    of a cohort study of 454 womenwith abnormal screening mammography and 908 matched control women withnormal results. Using a condition-specific questionnaire (Consequences of Screening in Breast Cancer), we assessed 12 psychosocial consequences at 5 time points (0, 1, 6, 18, and 36 months after final diagnosis......) and compared the 2 groups of women with false-positives (invasive and noninvasive management groups). RESULTS: Among the 252 women with false-positive mammography eligible forthis study, psychosocial consequences were similar for those managed invasivelyand those managed noninvasively during the 36 months...... between those of women withnormal mammography and those of women determined to have breast cancer. CONCLUSIONS: We found no evidence that use of more invasive diagnosticswas associated with worse psychosocial consequences. It is therefore reasonableto pool subgroups of women with false...

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

    Science.gov (United States)

    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…

  3. False-positive Human Papillomavirus DNA tests in cervical screening

    DEFF Research Database (Denmark)

    Rebolj, Matejka; Pribac, Igor; Lynge, Elsebeth

    2011-01-01

    Based on data from randomised controlled trials (RCT) on primary cervical screening, it has been reported that the problem of more frequent false-positive tests in Human Papillomavirus (HPV) DNA screening compared to cytology could be overcome. However, these reports predominantly operated with a...

  4. False-positive urine pregnancy tests clinicians as detectives ...

    African Journals Online (AJOL)

    Reliably diagnosing pregnancy in women presenting with nonspecific abdominal pain can be lifesaving. If diagnostic tests are unreliable, however, valuable time and resources can be wasted pursuing unnecessary and potentially harmful interventions. After four false positive-urine pregnancy tests in one week, we began ...

  5. Evaluation of false positivity and cross reactivity in the investigation ...

    African Journals Online (AJOL)

    This study evaluated the causes of false positive Human Immunodeficiency Virus test results (F+HIV), cross reactivity of HIV antibodies with other non HIV antibodies, and efficiency of the serial and parallel testing algorithms. 100 blood samples randomly collected from clients attending the Heart to Heart HIV counseling and ...

  6. Improved accuracy of cell surface shaving proteomics in Staphylococcus aureus using a false-positive control

    DEFF Research Database (Denmark)

    Solis, Nestor; Larsen, Martin Røssel; Cordwell, Stuart J

    2010-01-01

    Proteolytic treatment of intact bacterial cells is an ideal means for identifying surface-exposed peptide epitopes and has potential for the discovery of novel vaccine targets. Cell stability during such treatment, however, may become compromised and result in the release of intracellular proteins...... that complicate the final analysis. Staphylococcus aureus is a major human pathogen, causing community and hospital-acquired infections, and is a serious healthcare concern due to the increasing prevalence of multiple antibiotic resistances amongst clinical isolates. We employed a cell surface "shaving" technique...... to trypsin and three identified in the control. The use of a subtracted false-positive strategy improved enrichment of surface-exposed peptides in the trypsin data set to approximately 80% (124/155 peptides). Predominant surface proteins were those associated with methicillin resistance-surface protein SACOL...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  9. False positive acetaminophen concentrations in patients with liver injury

    Science.gov (United States)

    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.

    2013-01-01

    Background 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. Methods 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. Results 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. Conclusions 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. PMID:18279672

  10. Adrenocortical Carcinoma: False Positive in an I-123 Metaiodobenzylguanidine Scan

    Energy Technology Data Exchange (ETDEWEB)

    Rey, Cristina Rodriguez; Candil, Aida Ortega; Galvan, Eliseo Vano; Martin, Maria Nieves Cabrera; Delgado, Jose Luis Carreras [Clinico San Carlos Hospital, Madrid (Spain)

    2016-06-15

    A 55-year-old man with a personal his history of left pheochromocytoma 2 years previously presented with an abdominal ultrasound showed a large left upper quadrant solid mass (calipers), with heterogeneous echogenicity and central cystic degeneration areas or necrosis. F-18 Fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT was performed as ACC was suspected. ACC is an uncommon malignant neoplasm of unknown cause; however, smoking and oral contraceptives may be risk factors. Patients usually present with advanced-stage disease and have poor prognosis, with a 2-year recurrence rate that ranges form 73 to 86 %. An MIBG scan was performed after injection of 185 MBq of I-123 MIBG intravenously. Single photon emission tomography (SPECT)/CT scan showed abnormal isotope accumulation in the tumor region. The patient underwent total resection of the tumor. The histology was of ACC, with areas of necrosis and cystic areas, so the result of the MIBG scan was a false positive. Authors divided false-positive MIBG studies into three categories. The first category is neuroendocrine lesions other than pheochromocytomas (tumors of the APUD series). the second category consists in adrenal lesions other than pheochromocytomas (adenomas, ACC) the reasons for this abnormal uptake are unclear. The third category consists of tracer uptake adjacent to the adrenal due to abnormalities in the route of excretion.

  11. Adrenocortical Carcinoma: False Positive in an I-123 Metaiodobenzylguanidine Scan

    International Nuclear Information System (INIS)

    Rey, Cristina Rodriguez; Candil, Aida Ortega; Galvan, Eliseo Vano; Martin, Maria Nieves Cabrera; Delgado, Jose Luis Carreras

    2016-01-01

    A 55-year-old man with a personal his history of left pheochromocytoma 2 years previously presented with an abdominal ultrasound showed a large left upper quadrant solid mass (calipers), with heterogeneous echogenicity and central cystic degeneration areas or necrosis. F-18 Fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT was performed as ACC was suspected. ACC is an uncommon malignant neoplasm of unknown cause; however, smoking and oral contraceptives may be risk factors. Patients usually present with advanced-stage disease and have poor prognosis, with a 2-year recurrence rate that ranges form 73 to 86 %. An MIBG scan was performed after injection of 185 MBq of I-123 MIBG intravenously. Single photon emission tomography (SPECT)/CT scan showed abnormal isotope accumulation in the tumor region. The patient underwent total resection of the tumor. The histology was of ACC, with areas of necrosis and cystic areas, so the result of the MIBG scan was a false positive. Authors divided false-positive MIBG studies into three categories. The first category is neuroendocrine lesions other than pheochromocytomas (tumors of the APUD series). the second category consists in adrenal lesions other than pheochromocytomas (adenomas, ACC) the reasons for this abnormal uptake are unclear. The third category consists of tracer uptake adjacent to the adrenal due to abnormalities in the route of excretion.

  12. Tentacle probes: eliminating false positives without sacrificing sensitivity.

    Science.gov (United States)

    Satterfield, Brent C; West, Jay A A; Caplan, Michael R

    2007-01-01

    The majority of efforts to increase specificity or sensitivity in biosensors result in trade-offs with little to no gain in overall accuracy. This is because a biosensor cannot be more accurate than the affinity interaction it is based on. Accordingly, we have developed a new class of reagents based on mathematical principles of cooperativity to enhance the accuracy of the affinity interaction. Tentacle probes (TPs) have a hairpin structure similar to molecular beacons (MBs) for enhanced specificity, but are modified by the addition of a capture probe for increased kinetics and affinity. They produce kinetic rate constants up to 200-fold faster than MB with corresponding stem strengths. Concentration-independent specificity was observed with no false positives at up to 1 mM concentrations of variant analyte. In contrast, MBs were concentration dependent and experienced false positives above 3.88 muM of variant analyte. The fast kinetics of this label-free reagent may prove important for extraction efficiency, hence sensitivity and detection time, in microfluidic assays. The concentration-independent specificity of TPs may prove extremely useful in assays where starting concentrations and purities are unknown as would be the case in bioterror or clinical point of care diagnostics.

  13. Protein complex prediction via dense subgraphs and false positive analysis.

    Directory of Open Access Journals (Sweden)

    Cecilia Hernandez

    Full Text Available Many proteins work together with others in groups called complexes in order to achieve a specific function. Discovering protein complexes is important for understanding biological processes and predict protein functions in living organisms. Large-scale and throughput techniques have made possible to compile protein-protein interaction networks (PPI networks, which have been used in several computational approaches for detecting protein complexes. Those predictions might guide future biologic experimental research. Some approaches are topology-based, where highly connected proteins are predicted to be complexes; some propose different clustering algorithms using partitioning, overlaps among clusters for networks modeled with unweighted or weighted graphs; and others use density of clusters and information based on protein functionality. However, some schemes still require much processing time or the quality of their results can be improved. Furthermore, most of the results obtained with computational tools are not accompanied by an analysis of false positives. We propose an effective and efficient mining algorithm for discovering highly connected subgraphs, which is our base for defining protein complexes. Our representation is based on transforming the PPI network into a directed acyclic graph that reduces the number of represented edges and the search space for discovering subgraphs. Our approach considers weighted and unweighted PPI networks. We compare our best alternative using PPI networks from Saccharomyces cerevisiae (yeast and Homo sapiens (human with state-of-the-art approaches in terms of clustering, biological metrics and execution times, as well as three gold standards for yeast and two for human. Furthermore, we analyze false positive predicted complexes searching the PDBe (Protein Data Bank in Europe database in order to identify matching protein complexes that have been purified and structurally characterized. Our analysis shows

  14. Clinical Brain Death with False Positive Radionuclide Cerebral Perfusion Scans

    Directory of Open Access Journals (Sweden)

    Sindhaghatta Venkatram

    2015-01-01

    Full Text Available Practice guidelines from the American Academy of Neurology for the determination of brain death in adults define brain death as “the irreversible loss of function of the brain, including the brainstem.” Neurological determination of brain death is primarily based on clinical examination; if clinical criteria are met, a definitive confirmatory test is indicated. The apnea test remains the gold standard for confirmation. In patients with factors that confound the clinical determination or when apnea tests cannot safely be performed, an ancillary test is required to confirm brain death. Confirmatory ancillary tests for brain death include (a tests of electrical activity (electroencephalography (EEG and somatosensory evoked potentials and (b radiologic examinations of blood flow (contrast angiography, transcranial Doppler ultrasound (TCD, and radionuclide methods. Of these, however, radionuclide studies are used most commonly. Here we present data from two patients with a false positive Radionuclide Cerebral Perfusion Scan (RCPS.

  15. Polio vaccines, SV40 and human tumours, an update on false positive and false negative results.

    Science.gov (United States)

    Elmishad, A G; Bocchetta, M; Pass, H I; Carbone, M

    2006-01-01

    Simian virus 40 (SV40) has been detected in different human tumours in numerous laboratories. The detection of SV40 in human tumours has been linked to the administration of SV40-contaminated polio vaccines from 1954 until 1963. Many of these reports linked SV40 to human mesothelioma. Some studies have failed to detect SV40 in human tumours and this has caused a controversy. Here we review the current literature. Moreover, we present evidence showing how differences in the sensitivities of methodologies can lead to a very different interpretation of the same study. The same 20 mesothelioma specimens all tested negative, 2/20 tested positive or 7/20 tested positive for SV40 Tag by simply changing the detection method on the same immuno-precipitation/western blot membranes. These results provide a simple explanation for some of the apparent discordant results reported in the literature.

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

    Science.gov (United States)

    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.

  17. Factors associated with false-positive and false-negative fecal immunochemical test results for colorectal cancer screening.

    Science.gov (United States)

    Wong, Martin C S; Ching, Jessica Y L; Chan, Victor C W; Lam, Thomas Y T; Luk, Arthur K C; Ng, Simon S M; Sung, Joseph J Y

    2015-03-01

    Certain subgroups have higher rates of false fecal immunochemical test (FIT) results, yet few studies have addressed this topic. To identify demographic factors associated with false-positive and false-negative FIT results in colorectal cancer screening. Retrospective database review of prospectively collected data. A bowel cancer screening center in Hong Kong invited participants for colorectal cancer screening (2008-2012). Study participants who underwent both FIT and colonoscopy in the first year (n = 4482) and underwent colonoscopy after negative FIT results for 3 consecutive years (n = 857). The diagnostic accuracy and predictive values of FIT according to participant characteristics. The sensitivity, specificity, positive predictive values, and negative predictive values for advanced neoplasia were 33.1%, 91.9%, 19.0%, and 96.0%, respectively. Participants 66 to 70 years of age had higher sensitivity, whereas older age, smoking, and use of aspirin/nonsteroidal anti-inflammatory drugs were associated with lower specificity. The rates of false-positive and false-negative results were 8.1% and 66.9%, respectively. Older age (66-70 years; adjusted odds ratio [AOR] 1.95; 95% confidence interval [CI], 1.35-2.81; P negative results and the absence of high-grade dysplasia (AOR for presence 0.41) were associated with false-negative results. Self-referred participants who received one type of qualitative FIT. These findings could be used to target screening more toward those with a higher risk of false-negative results and those with a lower risk of false-positive results for earlier colonoscopy. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

  18. Risk of breast cancer after false-positive test results in screening mammography

    DEFF Research Database (Denmark)

    von Euler-Chelpin, My Catarina; Risør, Louise Madeleine; Thorsted, Brian Larsen

    2012-01-01

    Screening for disease in healthy people inevitably leads to some false-positive tests in disease-free individuals. Normally, women with false-positive screening tests for breast cancer are referred back to routine screening. However, the long-term outcome for women with false-positive tests...

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

    Science.gov (United States)

    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; PTB tended to induce false-positive results (OR 30.297; 95%CI 7.069-129.849; PTB (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.

  20. Look Again: An Investigation of False Positive Detections in Combat Models

    National Research Council Canada - National Science Library

    Wainwright, Ryan K

    2008-01-01

    .... Existing combat models tend to overlook or downplay false positive detections. Signal Detection Theory provides the framework for analysis of an observer's hits, misses, correct rejections, and false alarms...

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

    DEFF Research Database (Denmark)

    Roman, Marta; Castells, Xavier; Hofvind, Solveig

    2016-01-01

    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 ...

  2. Increased risk of breast cancer in women with false-positive test

    DEFF Research Database (Denmark)

    von Euler-Chelpin, My; Kuchiki, Megumi; Vejborg, Ilse

    2014-01-01

    INTRODUCTION: Studies have shown that women with a false-positive result from mammography screening have an excess risk for breast cancer compared with women who only have negative results. We aimed to assess the excess risk of cancer after a false-positive result excluding cases of misclassifica...

  3. Addressing False Positives in Early Reading Assessment Using Intervention Response Data

    Science.gov (United States)

    McAlenney, Athena Lentini; Coyne, Michael D.

    2015-01-01

    The current study examined a solution to high false positive reading risk classification rates in early kindergarten by investigating a method of identifying students with possible false positive risk classifications and returning them to general classroom instruction. Researchers assessed kindergarten students (N = 105) identified as at risk who…

  4. False-Positive Rate Determination of Protein Target Discovery using a Covalent Modification- and Mass Spectrometry-Based Proteomics Platform

    Science.gov (United States)

    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 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.

  5. A Case of Systemic Lupus Erythematosus Associated with False Positive VDRL and TPHA

    Directory of Open Access Journals (Sweden)

    Muzeyyen Gonul

    2008-09-01

    Full Text Available Systemic lupus erythematosus (SLE is a connective tissue disease characterized by vasculitis, which may involve multiple organs as well as the skin. Serologic tests for syphilis may be false positive in SLE. Although the false positivity of VDRL (Venereal Disease Research Laboratory is commonly seen, false positivity of TPHA (Treponema pallidum haemagglutination is a rare condition. We present a case of SLE with false positive VDRL and TPHA. A 26-year-old woman was admitted to our clinic with violaceous papules and plaques with whitish desquamation and erosions, and crusts on the face, arms and back. The histopathological examination of the skin biopsy supported the diagnosis of discoid lupus erythematosus. The diagnosis of SLE was based on the presence of photosensitivity and the detection of leukopenia, anemia and positivities of antinuclear antibody, anti DNA, and VDRL. In addition to these findings, TPHA was found to be positive, but the ELISA test for syphilis and FTA ABS Ig M were negative. The positivity of VDRL and TPHA were accepted as false positives. We would like to point out that the false positivity of TPHA, although more rarely encountered, as well as that of VDRL, may be observed in SLE patients.

  6. Association between false-positive TORCH and antiphospholipid antibodies in healthy pregnant women.

    Science.gov (United States)

    De Carolis, S; Tabacco, S; Rizzo, F; Perrone, G; Garufi, C; Botta, A; Salvi, S; Benedetti Panici, P; Lanzone, A

    2018-04-01

    The present study investigated: (a) the presence of antiphospholipid antibodies and (b) the obstetric outcome in healthy pregnant women showing false-positive TORCH-Toxoplasmosis, Other: syphilis, varicella-zoster, Rubella, Cytomegalovirus (CMV), and Herpes infections-results. Data from 23 singleton healthy pregnancies with false-positive TORCH results were collected. Each woman was systematically screened for TORCH IgG and IgM during the pre-conception assessment and/or at the beginning of pregnancy. In the presence of IgM positivity, when indicated (CMV, toxoplasmosis, rubella, herpes simplex virus), IgG avidity was evaluated and, if possible, polymerase chain reaction was performed on an amniotic fluid sample in order to distinguish between primary infection or false positivity. The antiphospholipid antibodies tests were: lupus anticoagulant, anticardiolipin antibodies IgG, IgM, and anti-β2glicoprotein I IgG, IgM. The antiphospholipid antibodies tests, if positive, were repeated after 12 weeks to confirm the results. In pregnant women with false-positive TORCH, the overall prevalence of positive antiphospholipid antibodies for one or more tests was 52.2%. To clarify the correlation of false-positive TORCH results with clinical practice, obstetric outcome was analyzed in terms of live births, week of delivery, neonatal birth weight, and neonatal birth weight percentile. A statistically significant lower neonatal birth weight and neonatal birth weight percentile were observed in women with false-positive TORCH associated with antiphospholipid antibodies positivity (Group A) in comparison with those in women with false-positive TORCH without antiphospholipid antibodies positivity (Group B). No statistically significant difference was found for the week of delivery between the two groups. It is hoped that future studies will verify the life-long persistence of antiphospholipid antibodies positivity by follow-up of these women and identify who will develop a

  7. Predicting the risk of a false-positive test for women following a mammography screening programme

    DEFF Research Database (Denmark)

    Njor, Sisse Helle; Olsen, Anne Helene; Schwartz, Walter

    2007-01-01

    OBJECTIVES: The objectives of this study was to provide a simple estimate of the cumulative risk of a false-positive test for women participating in mammography screening. To test the method, we used data from two well-established, organized mammography screening programmes offering biennial...... screening to women aged 50-69 years in Copenhagen and Fyn, Denmark. METHODS: We defined the outcome from a screen as being either a false-positive test or not a false-positive test. We then tested whether the outcomes from subsequent screens were independent, and afterwards estimated the risk over 10...

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

    Science.gov (United States)

    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

  9. The problem of false-positive human papillomavirus DNA tests in cervical screening

    DEFF Research Database (Denmark)

    Rebolj, Matejka; Pribac, Igor; Frederiksen, Maria Eiholm

    2013-01-01

    Human Papillomavirus (HPV) testing has been extensively studied in randomized controlled trials of primary cervical screening. Based on encouraging results concerning its high detection rates and a high negative predictive value for high-grade cervical intraepithelial neoplasia (CIN), HPV testing...... will probably replace cytology in future primary cervical screening. However, HPV testing is associated with more frequent false-positive tests compared to cytology. False-positive tests are defined as positive screening tests which are not subsequently confirmed with high-grade CIN. Several authors have...... testing leads to more screen-positive women being referred for colposcopy without having high-grade CIN, and to more women undergoing repeated testing. The only reasonable solution to the problem of false-positive tests appears to be a revised definition of a positive HPV screening test. However, further...

  10. Participation behaviour following a false positive test in the Copenhagen mammography screening programme

    DEFF Research Database (Denmark)

    Andersen, Sune Bangsbøll; Vejborg, Ilse; von Euler-Chelpin, My

    2008-01-01

    INTRODUCTION: There is an ongoing debate concerning possible disadvantages of mammography screening, one being the consequence of receiving a false positive test-result. It is argued that receiving a false positive answer may have short- and/or long-term adverse psychological effects on women......, but results from different studies are conflicting. We tested if there was a difference in continued participation behaviour between the group of women who have been subject to a false positive result and those who have not. MATERIAL AND METHODS: The study used the registers from the first six invitation...... rounds of the mammography screening programme in Copenhagen (1991-2003). We estimated the relative risk of not participating in the subsequent screening round for women with a false positive test using women with a negative test as baseline. As outcome measure odds ratios (OR) with 95% confidence...

  11. Psychological effects of false-positive results in expanded newborn screening in China.

    Directory of Open Access Journals (Sweden)

    Wen-Jun Tu

    Full Text Available OBJECTIVES: As more families participate expanded newborn screening for metabolic disorders in China, the overall number of false positives increases. Our goal was to assess the potential impact on parental stress, perceptions of the child's health, and family relationships. METHODS: Parents of 49 infants with false-positive screening results for metabolic disorders in the expanded newborn screening panel were compared with parents of 42 children with normal screening results. Parents first completed structured interview using likert scales, closed and open questions. Parents also completed the parenting stress index. RESULTS: A total of 88 mothers and 41 fathers were interviewed. More mothers in the false-positive group reported that their children required extra parental care (21%, compared with 5% of mothers in the normal-screened group (P<0.001. 39% of mothers in the false-positive group reported that they worry about their child's future development, compared with 10% of mothers in the normal-screened group (P<0.001. Fathers in the false-positive group did not differ from fathers in the normal-screened group in reporting worry about their child's extra care requirements, and their child's future development. Children with false-positive results compared with children with normal results were triple as likely to experience hospitalization (27%vs 9%, respectively; P<0.001. CONCLUSIONS: The results showing false-positive screening results may affect parental stress and the parent-child relationship. Parental stress and anxiety can be reduced with improved education and communication to parents about false-positive results.

  12. Novel approach to control false positive rate in fuzzy cluster analysis of fMRI

    Science.gov (United States)

    Jahanian, Hesamoddin; Soltanian-Zadeh, Hamid; Hossein-Zadeh, Gholam-Ali

    2004-04-01

    Fuzzy c-means (FCM) suffers from some limitations such as the need for a priori knowledge of the number of clusters, and unknown statistical significance and instability of the results, when it is applied to the raw fMRI time series. Based on randomization, we developed a method to control the false positive detection rate in FCM and estimate the statistical significance of the results. Using this novel approach, we proposed an fMRI activation detection method which uses FCM with controlled false positive rate. The ability of the method in controlling the false positive rate is shown by an analysis of false positives in activation maps of resting-state fMRI data. Controlling the false positive rate allows comparison of different feature spaces and fuzzy clustering methods. A new feature space, in multi and scalar wavelet domain, is proposed for activation detection in fMRI to address the stability problem. Finally, using the proposed method for controlling the false positive rate, the proposed feature space is compared to the cross-correlation feature space.

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

    Science.gov (United States)

    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.

  14. Peptide-Mediated Liposome Fusion: The Effect of Anchor Positioning

    Directory of Open Access Journals (Sweden)

    Niek S. A. Crone

    2018-01-01

    Full Text Available A minimal model system for membrane fusion, comprising two complementary peptides dubbed “E” and “K” joined to a cholesterol anchor via a polyethyleneglycol spacer, has previously been developed in our group. This system promotes the fusion of large unilamellar vesicles and facilitates liposome-cell fusion both in vitro and in vivo. Whilst several aspects of the system have previously been investigated to provide an insight as to how fusion is facilitated, anchor positioning has not yet been considered. In this study, the effects of placing the anchor at either the N-terminus or in the center of the peptide are investigated using a combination of circular dichroism spectroscopy, dynamic light scattering, and fluorescence assays. It was discovered that anchoring the “K” peptide in the center of the sequence had no effect on its structure, its ability to interact with membranes, or its ability to promote fusion, whereas anchoring the ‘E’ peptide in the middle of the sequence dramatically decreases fusion efficiency. We postulate that anchoring the ‘E’ peptide in the middle of the sequence disrupts its ability to form homodimers with peptides on the same membrane, leading to aggregation and content leakage.

  15. The relationship between TORCH complex false positivity and obstetric outcome in patients with antiphospholipid syndrome.

    Science.gov (United States)

    De Carolis, S; Santucci, S; Botta, A; Salvi, S; Degennaro, V A; Garufi, C; Garofalo, S; Ferrazzani, S; Scambia, G

    2012-06-01

    The presence of TORCH IgM positivity is not a specific indicator of primary infection; the assessment of IgG avidity index has been shown to be useful in identifying or excluding primary infection in pregnant women with no pre-gestational TORCH serology. TORCH is an acronym for Toxoplasmosis, Others (HBV, syphilis, Varicella-Zoster virus, Epstein Barr virus, Coxsackie virus and Parvovirus), Rubella, Cytomegalovirus (CMV) and Herpes Simplex. Data from 54 pregnancies in women with antiphospholipid syndrome (APS) were assessed in comparison with data from 222 healthy pregnant women as controls. Each woman in both groups was systematically screened for TORCH IgG and IgM during pre-conceptional evaluation and/or at the beginning of pregnancy. The assessment of IgG avidity was also evaluated in order to identify primary infection or false positivity. A significant increase of CMV IgM false positivity in APS in comparison with controls was detected. A worse pregnancy outcome was observed among APS patients having CMV IgM false positivity in comparison with APS patients without false positivity; in particular a statistically significant lower neonatal birth weight and a lower neonatal birth weight percentile were observed. Our data suggest that the presence of CMV IgM false positivity could represent a novel prognostic factor for poor pregnancy outcome in APS patients.

  16. GeneWaltz--A new method for reducing the false positives of gene finding

    Directory of Open Access Journals (Sweden)

    Misawa Kazuharu

    2010-09-01

    Full Text Available Abstract Background Identifying protein-coding regions in genomic sequences is an essential step in genome analysis. It is well known that the proportion of false positives among genes predicted by current methods is high, especially when the exons are short. These false positives are problematic because they waste time and resources of experimental studies. Methods We developed GeneWaltz, a new filtering method that reduces the risk of false positives in gene finding. GeneWaltz utilizes a codon-to-codon substitution matrix that was constructed by comparing protein-coding regions from orthologous gene pairs between mouse and human genomes. Using this matrix, a scoring scheme was developed; it assigned higher scores to coding regions and lower scores to non-coding regions. The regions with high scores were considered candidate coding regions. One-dimensional Karlin-Altschul statistics was used to test the significance of the coding regions identified by GeneWaltz. Results The proportion of false positives among genes predicted by GENSCAN and Twinscan were high, especially when the exons were short. GeneWaltz significantly reduced the ratio of false positives to all positives predicted by GENSCAN and Twinscan, especially when the exons were short. Conclusions GeneWaltz will be helpful in experimental genomic studies. GeneWaltz binaries and the matrix are available online at http://en.sourceforge.jp/projects/genewaltz/.

  17. Performance quantification of clustering algorithms for false positive removal in fMRI by ROC curves

    Directory of Open Access Journals (Sweden)

    André Salles Cunha Peres

    Full Text Available Abstract Introduction Functional magnetic resonance imaging (fMRI is a non-invasive technique that allows the detection of specific cerebral functions in humans based on hemodynamic changes. The contrast changes are about 5%, making visual inspection impossible. Thus, statistic strategies are applied to infer which brain region is engaged in a task. However, the traditional methods like general linear model and cross-correlation utilize voxel-wise calculation, introducing a lot of false-positive data. So, in this work we tested post-processing cluster algorithms to diminish the false-positives. Methods In this study, three clustering algorithms (the hierarchical cluster, k-means and self-organizing maps were tested and compared for false-positive removal in the post-processing of cross-correlation analyses. Results Our results showed that the hierarchical cluster presented the best performance to remove the false positives in fMRI, being 2.3 times more accurate than k-means, and 1.9 times more accurate than self-organizing maps. Conclusion The hierarchical cluster presented the best performance in false-positive removal because it uses the inconsistency coefficient threshold, while k-means and self-organizing maps utilize a priori cluster number (centroids and neurons number; thus, the hierarchical cluster avoids clustering scattered voxels, as the inconsistency coefficient threshold allows only the voxels to be clustered that are at a minimum distance to some cluster.

  18. Frequency of a false positive diagnosis of epilepsy: A systematic review of observational studies.

    Science.gov (United States)

    Xu, Ying; Nguyen, Dennis; Mohamed, Armin; Carcel, Cheryl; Li, Qiang; Kutlubaev, Mansur A; Anderson, Craig S; Hackett, Maree L

    2016-10-01

    To determine the frequency of false positive diagnoses of epilepsy and to explore its imitators and consequences. A systematic review of all published observational studies (to November 2015) was conducted to determine the proportion of false positive diagnoses of epilepsy. We included studies of people of all ages receiving a diagnosis of epilepsy. All observational study designs were included with the exception of case-reports and case series with fewer than 3 participants. Data were available from 27 studies (31 reports), reporting considerably varied frequencies of false positive diagnoses. The frequency of false positive diagnosis range from 2% to 71%. The data also suggest that syncope and psychogenic non-epileptic paroxysmal events were the commonest imitators of epilepsy. Misdiagnosis led to mismanagement with anti-epileptic drugs (AEDs) and affected legal driving status and employment. False positive diagnosis of epilepsy is common, even though there is considerable heterogeneity across studies. All potential imitators should be considered and clinicians should be cautious introducing AEDs without a definite diagnosis given the risk of side effects, and the possible impact on legal driving status and employment. Copyright © 2016 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

  19. Retrospective analysis for the false positive diagnosis of PET-CT scan in lung cancer patients.

    Science.gov (United States)

    Feng, Mingxia; Yang, Xuemei; Ma, Qiang; He, Yong

    2017-10-01

    Early diagnosis is pivotal for prognosis of lung cancer patients. Positron emission tomography/computed tomography (PET-CT) is a useful method for human cancer diagnosis. In this study, we aimed to explore the false positive diagnosis of PET-CT in lung cancerIn total, 754 patients diagnosed with lung cancer via PET-CT were retrospectively collected in this study. Histopathological detection served as gold standard. The diagnostic accuracy of PET-CT was defined as the proportion of lung cancer cases confirmed by pathological diagnosis in the study subjects, and the percentages of misdiagnosed cases represented the false positive diagnosis of PET-CT. Chi-square test and logistic regression analysis were used to analyze the association of pathologically confirmed result with clinical characteristics.Among all the patients, 705 cases were pathologically confirmed with lung cancer. The diagnostic accuracy of PET-CT was 93.5%, and the false positive rate was 6.50%. Among the false positive patients, inflammatory pseudotumor (42.86%) and tuberculoma (36.74%) were the most pathological types. In the positive detection group, adenocarcinoma (57.16%) and squamous carcinoma (33.19%) were the main pathological types, and 68.09% of the lung cancer patients were at the advanced stages. The false positive rate were related with age, diabetes, interleukin-6 (IL-6) level, and T-spot test (all P < .05).PET-CT could be a good diagnostic method for lung cancer, but the false positive cases could appear. Detection of inflammatory indicators such as IL-6 and T-spot TB test may help improve the diagnostic accuracy of PET-CT.

  20. Influence of false-positive mammography results on subsequent screening: do physician recommendations buffer negative effects?

    Science.gov (United States)

    DeFrank, Jessica T; Rimer, Barbara K; Bowling, J Michael; Earp, Jo Anne; Breslau, Erica S; Brewer, Noel T

    2012-03-01

    Cancer screening guidelines often include discussion about the unintended negative consequences of routine screening. This prospective study examined effects of false-positive mammography results on women's adherence to subsequent breast cancer screening and psychological well-being. We also assessed whether barriers to screening exacerbated the effects of false-positive results. We conducted secondary analyses of data from telephone interviews and medical claims records for 2406 insured women. The primary outcome was adherence to screening guidelines, defined as adherent (10-14 months), delayed (15-34 months), or no subsequent mammogram on record. About 8% of women reported that their most recent screening mammograms produced false-positive results. In the absence of self-reported advice from their physicians to be screened, women were more likely to have no subsequent mammograms on record if they received false-positive results than if they received normal results (18% vs. 7%, OR = 3.17, 95% CI = 1.30, 7.70). Receipt of false-positive results was not associated with this outcome for women who said their physicians had advised regular screening in the past year (7% vs. 10%, OR = 0.74, 95% CI = 0.38, 1.45). False-positive results were associated with greater breast cancer worry (P thinking more about the benefits of screening (P positive mammography results, coupled with reports that women's physicians did not advise regular screening, could lead to non-adherence to future screening. Abnormal mammograms that do not result in cancer diagnoses are opportunities for physicians to stress the importance of regular screening.

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

    Science.gov (United States)

    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.

  2. Image Watermarking Scheme for Specifying False Positive Probability and Bit-pattern Embedding

    Science.gov (United States)

    Sayama, Kohei; Nakamoto, Masayoshi; Muneyasu, Mitsuji; Ohno, Shuichi

    This paper treats a discrete wavelet transform(DWT)-based image watermarking with considering the false positive probability and bit-pattern embedding. We propose an iterative embedding algorithm of watermarking signals which are K sets pseudo-random numbers generated by a secret key. In the detection, K correlations between the watermarked DWT coefficients and watermark signals are computed by using the secret key. L correlations are made available for the judgment of the watermark presence with specified false positive probability, and the other K-L correlations are corresponding to the bit-pattern signal. In the experiment, we show the detection results with specified false positive probability and the bit-pattern recovery, and the comparison of the proposed method against JPEG compression, scaling down and cropping.

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

    Science.gov (United States)

    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.

  4. Reducing False-Positive Pregnancy Test Results in Patients With Cancer.

    Science.gov (United States)

    McCash, Samuel I; Goldfrank, Deborah J; Pessin, Melissa S; Ramanathan, Lakshmi V

    2017-10-01

    To assess whether the use of a laboratory test specific for intact human chorionic gonadotropin (hCG) would reduce the number of false-positive pregnancy test results. From October 21, 2014, to January 20, 2015, and April 1, 2015, to June 2, 2015, all serum samples sent for pregnancy screening at a large cancer center with a value of 5 milli-international units/mL or greater total β-hCG were frozen and stored and then retested using intact hCG reagent. We compared the accuracy of total β-hCG and intact hCG results for the diagnosis of clinically confirmed pregnancy. A negative test was defined as 14 milli-international units/mL or less, our current institutional cutoff. We also assessed a cutoff of less than 5 milli-international units/mL, a historical cutoff to rule out pregnancy. We performed intact hCG testing on 64 patient samples, of which 34 had originally resulted positive when tested for total β-hCG. These included 21 cases of clinically confirmed pregnancy and 13 false-positive cases. No women were pregnant when their intact hCG concentration was 14 milli-international units/mL or less, and all pregnancies were detected at and above this concentration. Intact hCG reduced the number of false-positive pregnancy test results from 13 to 1, a 92% reduction (95% CI 64-99%), corresponding to a reduction in the false-positive rate from 38% (95% CI 22-56%) to 3% (95% CI 1-15%). The use of intact hCG reagent in patients with cancer reduces the rate of false-positive pregnancy test results without increasing the rate of false-negative test results.

  5. Categorizing Mistaken False Positives in Regulation of Human and Environmental Health

    DEFF Research Database (Denmark)

    Hansen, Steffen Foss; Krayer von Krauss, Martin Paul; Tickner, J.A.

    2007-01-01

    ," 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...

  6. Waiting time and the psychosocial consequences of false-positive mammography

    DEFF Research Database (Denmark)

    Heleno, Bruno M.; Siersma, Volkert; Brodersen, John

    2015-01-01

    Background: There is wide variation in the psychosocial response to false-positive mammography. We aimed to assess whether women having to wait longer to exclude cancer had increased psychosocial consequences that persisted after cancer was ruled out. Findings: We selected women with false......-positive mammography (n = 272), screened for breast cancer in Copenhagen and Funen (Denmark) over a 1-year period. We measured psychosocial consequences immediately before women attended their recall visit and 1, 6, 18 and 36 months after women received their final diagnosis. After women were told that cancer had been...

  7. Incidence and impact of false-positive urine pneumococcal antigen testing in hospitalized patients.

    Science.gov (United States)

    Ryscavage, Patrick A; Noskin, Gary A; Bobb, Anne; Bardowski, Laura; Zembower, Teresa R

    2011-08-01

    Immunochromatographic urine pneumococcal antigen testing (ICT) has become a common diagnostic tool for those presenting with possible invasive pneumococcal disease. The incidence and clinical impact of ICT false-positivity on hospitalized patients has not been assessed outside of specific patient subpopulations. ICT performance needs to be assessed in a real-world clinical setting. This study aims to describe the incidence and clinical impact of ICT false-positivity in a hospital setting over a 19-month period. A retrospective cohort study was performed to assess the incidence of false-positive (FP) ICT among hospitalized patients from November 21, 2007 to June 30, 2009. The primary objective was to describe the incidence of FP ICT results. The secondary objective was to describe what clinical impact, if any, could be attributed to FP ICT results. During the study period, 52 positive ICT results were obtained, of which 5 (9.6%) were deemed falsely positive. Interestingly, two of the 5 FP results were from patients who had received 23-valent pneumococcal vaccine (PPV) in the 2 days prior to ICT. The management of all 5 patients was impacted by the FP results through unnecessary antimicrobial treatment and/or deferral of further clinical evaluation. Health care providers should be aware of the potential for ICT FP and should order and interpret these tests within an informed clinical framework.

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

    Directory of Open Access Journals (Sweden)

    Baveewo Steven

    2012-03-01

    Full Text Available Abstract 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.

  9. False memory for positive and negative life events. The role of mental imagery

    Directory of Open Access Journals (Sweden)

    Mairean, C.

    2015-07-01

    Full Text Available A false memory appears when a person recalls memories of events that did not actually happen to him or her. The present study focused on situational and personal determinants of spontaneous false memories. Specifically, we aimed to investigate the role of emotional valence of an event, as well as the individual differences in mental imagery in evocation false memory. Three videos in which related details were not shown but were presented during a recognition task were used to induce spontaneous false memories. The three videos are different in terms of valence, reflecting positive, negative and neutral events. A scale for measuring mental imagery was also used. A sample of 132 participants completed the study. The results showed that the positive event lead to a higher level of false memory than the negative event. Moreover, the participants differ in their susceptibility to false memories based on the level of imagery, but the interaction between the emotional valence of the event and mental imagery is not significant. The results are discussed from the perspective of their legal and clinical implications.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mordang, Jan-Jurre, E-mail: Jan-Jurre.Mordang@radboudumc.nl; Gubern-Mérida, Albert; Karssemeijer, Nico [Diagnostic Image Analysis Group, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen 6525 GA (Netherlands); Heeten, Gerard den [The National Training Centre for Breast Cancer Screening, Nijmegen 6503 GJ, The Netherlands and Department of Radiology, Amsterdam Medical Center, Amsterdam 1100 DD (Netherlands)

    2016-04-15

    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 performance 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 specificity

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

    Science.gov (United States)

    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...

  12. Predicting the risk of a false-positive test for women following a mammography screening programme

    DEFF Research Database (Denmark)

    Njor, Sisse Helle; Olsen, Anne Helene; Schwartz, Walter

    2007-01-01

    OBJECTIVES: The objectives of this study was to provide a simple estimate of the cumulative risk of a false-positive test for women participating in mammography screening. To test the method, we used data from two well-established, organized mammography screening programmes offering biennial...... be calculated in a simple way relatively early after the start of a mammography screening programme....

  13. Long-term psychosocial consequences of false-positive screening mammography

    DEFF Research Database (Denmark)

    Brodersen, John; Siersma, Volkert Dirk

    2013-01-01

    Cancer screening programs have the potential of intended beneficial effects, but they also inevitably have unintended harmful effects. In the case of screening mammography, the most frequent harm is a false-positive result. Prior efforts to measure their psychosocial consequences have been limited...

  14. Examination of long-lasting parental concern after false-positive results of neonatal hearing screening

    NARCIS (Netherlands)

    Ploeg, C.P.B. van der; Lanting, C.I.; Kauffman-Boer, M.A. de; Uilenburg, N.N.; Ridder-Sluiter, J.G. de; Verkerk, P.H.

    2008-01-01

    Objective: To investigate whether false-positive outcomes on neonatal hearing screening cause long-lasting parental concerns. Methods: A general population of parents whose children had participated in the universal neonatal hearing screening (UNHS) programme were examined. Parents filled out a

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

    Science.gov (United States)

    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…

  16. A method to reduce ancestry related germline false positives in tumor only somatic variant calling

    Directory of Open Access Journals (Sweden)

    Rebecca F. Halperin

    2017-10-01

    Full Text Available Abstract Background Significant clinical and research applications are driving large scale adoption of individualized tumor sequencing in cancer in order to identify tumors-specific mutations. When a matched germline sample is available, somatic mutations may be identified using comparative callers. However, matched germline samples are frequently not available such as with archival tissues, which makes it difficult to distinguish somatic from germline variants. While population databases may be used to filter out known germline variants, recent studies have shown private germline variants result in an inflated false positive rate in unmatched tumor samples, and the number germline false positives in an individual may be related to ancestry. Methods First, we examined the relationship between the germline false positives and ancestry. Then we developed and implemented a tumor only caller (LumosVar that leverages differences in allelic frequency between somatic and germline variants in impure tumors. We used simulated data to systematically examine how copy number alterations, tumor purity, and sequencing depth should affect the sensitivity of our caller. Finally, we evaluated the caller on real data. Results We find the germline false-positive rate is significantly higher for individuals of non-European Ancestry largely due to the limited diversity in public polymorphism databases and due to population-specific characteristics such as admixture or recent expansions. Our Bayesian tumor only caller (LumosVar is able to greatly reduce false positives from private germline variants, and our sensitivity is similar to predictions based on simulated data. Conclusions Taken together, our results suggest that studies of individuals of non-European ancestry would most benefit from our approach. However, high sensitivity requires sufficiently impure tumors and adequate sequencing depth. Even in impure tumors, there are copy number alterations that result

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

    Science.gov (United States)

    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.

  18. False positive rate of rapid oral fluid HIV tests increases as kits near expiration date.

    Directory of Open Access Journals (Sweden)

    Shelley N Facente

    Full Text Available BACKGROUND: Because a recent cluster of false positive results on the OraQuick ADVANCE Rapid HIV-1/2 Antibody Test occurred in San Francisco on test kits close to their expiration date, we decided to assess the relationship between time to expiration and rate of false positive results from tests used with oral fluid. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed results of 20,904 tests with either an initial HIV-negative result (n = 20,828 or a preliminary positive result that was then negative on confirmatory tests (n = 76. We computed specificity for kits with time to expiration from or = 6 months, with exact binomial confidence intervals, then used logistic regression to estimate the independent association of time to expiration with false positive results, adjusting for site and technician effects. For 1,108 kits used in the last month before expiration, specificity was 98.83% (95% exact binomial confidence interval (CI 98.00%-99.37%; the upper bound is below the claimed specificity of 99.60%. After adjustment using regression standardization for the effects of site, test lot, and technician factors, adjusted specificity in the last month before expiration was 99.18% (95% bootstrap confidence interval 98.60-99.57%. CONCLUSIONS/SIGNIFICANCE: We found that specificity of the OraQuick ADVANCE with oral fluid declined significantly with < or = 1 month remaining to expiration, leaving little margin for error from other sources.

  19. False positive seroreactivity to brucellosis in tuberculosis patients: a prevalence study

    Directory of Open Access Journals (Sweden)

    Mojtaba Varshochi

    2011-03-01

    Full Text Available Mojtaba Varshochi1,2, Jafar Majidi2, Marjan Amini1, Kamyar Ghabili3, Mohammadali M Shoja31Department of Infectious Disease, Tabriz University of Medical Sciences, Tabriz, Iran; 2Infectious Disease and Tropical Medicine Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; 3Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences, Tabriz, IranBackground: The rising worldwide incidence of tuberculosis (TB increases the demand for knowledge about its potential seroreactivity with other microbial agents. A few reports and the authors’ experiences indicate that tuberculosis may result in a false-positive brucellosis serology. This may cause a diagnostic challenge because of the close clinical resemblance of these two infections.Objective: The aim of the present prevalence study was to elucidate brucellosis seroreactivity in patients with active TB.Methods: Ninety-eight patients with newly diagnosed and active TB were studied using an enzyme-linked immunosorbent assay (ELISA and Wright’s and Coombs–Wright’s tests. Seventy-five healthy individuals were used as controls. The patients showed signs of recovery after starting a standard anti-TB regimen and had no clinical evidence of brucellosis at a subsequent 6-month follow-up. The data were analyzed statistically by Fisher’s exact test using SPSS 11.0.Results: We found that 9.2% of TB patients versus 1.3% of healthy controls had positive results on the anti-Brucella IgG ELISA (P = 0.04. Five TB patients were found to have agglutination on Wright’s tests, while none of the controls showed agglutination.Conclusion: Active TB patients may have some seroreactivity with Brucella antigens, and Brucella IgG ELISA may give a false positive in these patients. Clinicians should consider false positive brucellosis seroreactivity in patients with active TB.Keywords: false positive serology, ELISA, diagnosis

  20. Diagnostic Issues and Controversies in DSM-5: Return of the False Positives Problem.

    Science.gov (United States)

    Wakefield, Jerome C

    2016-01-01

    The fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) was the most controversial in the manual's history. This review selectively surveys some of the most important changes in DSM-5, including structural/organizational changes, modifications of diagnostic criteria, and newly introduced categories. It analyzes why these changes led to such heated controversies, which included objections to the revision's process, its goals, and the content of altered criteria and new categories. The central focus is on disputes concerning the false positives problem of setting a valid boundary between disorder and normal variation. Finally, this review highlights key problems and issues that currently remain unresolved and need to be addressed in the future, including systematically identifying false positive weaknesses in criteria, distinguishing risk from disorder, including context in diagnostic criteria, clarifying how to handle fuzzy boundaries, and improving the guidelines for "other specified" diagnosis.

  1. Analysis of False Positive Errors of an Acute Respiratory Infection Text Classifier due to Contextual Features.

    Science.gov (United States)

    South, Brett R; Shen, Shuying; Chapman, Wendy W; Delisle, Sylvain; Samore, Matthew H; Gundlapalli, Adi V

    2010-03-01

    Text classifiers have been used for biosurveillance tasks to identify patients with diseases or conditions of interest. When compared to a clinical reference standard of 280 cases of Acute Respiratory Infection (ARI), a text classifier consisting of simple rules and NegEx plus string matching for specific concepts of interest produced 569 (4%) false positive (FP) cases. Using instance level manual annotation we estimate the prevalence of contextual attributes and error types leading to FP cases. Errors were due to (1) Deletion errors from abbreviations, spelling mistakes and missing synonyms (57%); (2) Insertion errors from templated document structures such as check boxes, and lists of signs and symptoms (36%) and; (3) Substitution errors from irrelevant concepts and alternate meanings for the same word (6%). We demonstrate that specific concept attributes contribute to false positive cases. These results will inform modifications and adaptations to improve text classifier performance.

  2. The scope of false-positive iodine-131 images for thyroid carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Greenler, D.P.; Klein, H.A.

    1989-02-01

    Iodine-131 is used to detect and treat functioning lesions of papillary and follicular carcinoma of the thyroid. False-positive images although rare, do occur, with major categories being (1) body secretions, (2) pathologic transudates and inflammation, (3) nonspecific mediastinal uptake, and (4) neoplasms of nonthyroidal origin. The authors present eight cases that fall into the first three categories, including three types not previously reported--a lymphoepithelial cyst, a scrotal hydrocele, and a skin burn. The classification of mediastinal uptake as false positive is tentative. High-dose images and those exploiting therapeutic doses have an increased detection rate for both true and spurious lesions. Appropriate caution is advised in the interpretation of I-131 images.

  3. Newly formed skeletal muscle fibers are prone to false positive immunostaining by rabbit antibodies

    DEFF Research Database (Denmark)

    Andersen, Ditte C; Kliem, Anette; Schrøder, Henrik Daa

    2011-01-01

    Reports on muscle biology and regeneration often implicate immuno(cyto/histo)chemical protein characterization using rabbit polyclonal antibodies. In this study we demonstrate that newly formed myofibers are especially prone to false positive staining by rabbit antibodies and this unwanted staining...... is only recognized (1) by a negative muscle tissue control that does not harbor the protein to be examined (fx. from knockout mouse) or (2) by use of a nonsense rabbit antibody that has been prepared in the same way as the antibody of interest. However, many muscle immuno(cyto/histo)chemical studies only...... rely on controls that reveal non-specific binding by the secondary antibody and neglect that the primary rabbit antibody itself may cause false positive staining of the muscle. We suggest that reliable immuno-based protein detection in newly formed muscle fibers at least requires a nonsense rabbit...

  4. Cross-reactive Carbohydrate Determinant Contributes to the False Positive IgE Antibody to Peanut

    Directory of Open Access Journals (Sweden)

    Komei Ito

    2005-01-01

    Conclusions: Social education about the features of peanut allergy is needed in Japan. Anti-CCD IgE antibody was suggested to be one of the mechanisms contributing to the false positive detection of peanut IgE. Detection of anti-HRP or anti-bromelain IgE can be a useful tool to recognize the presence of anti-CCD antibodies.

  5. False-positive indium-111 labeled leukocyte scintigram in a patient with a painful hip prosthesis

    International Nuclear Information System (INIS)

    Feldman, N.; Makler, P.T. Jr.; Alavi, A.

    1986-01-01

    A Tronzo hip prosthesis is designed to elicit an inflammatory reaction in order to promote prosthesis stability. A three-phased bone scan and Ga-67 imaging in conjunction with physical examination and laboratory findings failed to demonstrate evidence for osteomyelitis in a patient with a painful hip prosthesis, in whom images obtained with In-111-labeled leukocytes were positive. This observation demonstrated that the interpretation of the latter technique in demonstrating inflammation can cause a false impression of an infectious process

  6. Shape based automated detection of pulmonary nodules with surface feature based false positive reduction

    International Nuclear Information System (INIS)

    Nomura, Y.; Itoh, H.; Masutani, Y.; Ohtomo, K.; Maeda, E.; Yoshikawa, T.; Hayashi, N.

    2007-01-01

    We proposed a shape based automated detection of pulmonary nodules with surface feature based false positive (FP) reduction. In the proposed system, the FP existing in internal of vessel bifurcation is removed using extracted surface of vessels and nodules. From the validation with 16 chest CT scans, we find that the proposed CAD system achieves 18.7 FPs/scan at 90% sensitivity, and 7.8 FPs/scan at 80% sensitivity. (orig.)

  7. Expected Planet and False Positive Detection Rates for the Transiting Exoplanet Survey Satellite

    OpenAIRE

    Brown, Timothy M.; Latham, David W.

    2008-01-01

    The proposed Transiting Exoplanet Survey Satellite (TESS) will survey the entire sky to locate the nearest and brightest transiting extrasolar planets with orbital periods up to about 36 days. Here we estimate the number and kind of astrophysical false positives that TESS will report, along with the number of extrasolar planets. These estimates are then used to size the ground-based follow-up observing efforts needed to confirm and characterize the planets. We estimate that the needed observi...

  8. Heterophilic antibodies interfering with radioimmunoassay. A false-positive pregnancy test

    Energy Technology Data Exchange (ETDEWEB)

    Vladutiu, A.O.; Sulewski, J.M.; Pudlak, K.A.; Stull, C.G.

    1982-11-19

    A young woman with amenorrhea had a consistently positive pregnancy test result (serum radioimmunoassay measurement of ..beta..-human chorionic gonadotropin hormone). No fetal or placental tissue was found after uterine curettage and exploratory laparotomy. The false-positive pregnancy test result was due to heterophilic antibovine and antigoat antibodies in the patient's serum. These antibodies interfered with radioimmunoassays using goat antibodies. This case shows that serum heterophilic antibodies can interfere with immunoassays and result in unnecessary diagnostic procedures and/or unnecessary treatment.

  9. Heterophilic antibodies interfering with radioimmunoassay. A false-positive pregnancy test

    International Nuclear Information System (INIS)

    Vladutiu, A.O.; Sulewski, J.M.; Pudlak, K.A.; Stull, C.G.

    1982-01-01

    A young woman with amenorrhea had a consistently positive pregnancy test result (serum radioimmunoassay measurement of #betta#-human chorionic gonadotropin hormone). No fetal or placental tissue was found after uterine curettage and exploratory laparotomy. The false-positive pregnancy test result was due to heterophilic antibovine and antigoat antibodies in the patient's serum. These antibodies interfered with radioimmunoassays using goat antibodies. This case shows that serum heterophilic antibodies can interfere with immunoassays and result in unnecessary diagnostic procedures and/or unnecessary treatment

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

    Science.gov (United States)

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

    2018-03-03

    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.

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

    Science.gov (United States)

    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.

  12. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria.

    Science.gov (United States)

    Nawrocki, Kathryn L; Crispell, Emily K; McBride, Shonna M

    2014-10-13

    Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis.

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

    NARCIS (Netherlands)

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

    2017-01-01

    Purpose: 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

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

    NARCIS (Netherlands)

    Mordang, J.J.; Gubern Merida, A.; Bria, A.; Tortorella, F.; Heeten, G.; Karssemeijer, N.

    2017-01-01

    PURPOSE: 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

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

    Science.gov (United States)

    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.

  16. False-Positive TDxFLx urine Amphetamine/Metamphetamine II assay from Ofloxacin

    International Nuclear Information System (INIS)

    Nomier, Mahmoud A.; Al-Huseini, Hani K.

    2004-01-01

    Immunoassays are widely used in testing urine for illicit drugs. Ofloaxcin and a number of other quinolones were found to induce false-positive opiates (OP) urine immunoassays. This can result in misleading conclusions in the concept of drug abuse The aim of present study was to evaluate the effects of ofloxacin in theraputic doses on the induction of false-positive urine immunoassays for common drugs of abuse in healthy male volunteers. The study was conducted on 6 healthy male volunteers, aging between 35-45 years. Two doses of 400 mg ofloxacin each, were given orally to each volunteer at 12 hours interval and urine samples were collected before ofloaxcin administration and 5-7.5 hours after the second dose. Urine samples were subjected for OP, amphetamine/methamphetamine II (AM/MA II), cocaine and cannabinoids assays on TDxFLx analyzer. Ofloxacin produced significant increase (P cutoff) for AM/MA II assays, were found in all volunteers after ofloaxcin administration. The study recomends strongly the confirmation of positive urine immunoassay results for drugs of abuseby a more specific methodology e.g. gas chromatography/ mass spectroscopy (GC/MS). (author)

  17. False-positive reduction in CAD mass detection using a competitive classification strategy

    International Nuclear Information System (INIS)

    Li Lihua; Zheng Yang; Zhang Lei; Clark, Robert A.

    2001-01-01

    High false-positive (FP) rate remains to be one of the major problems to be solved in CAD study because too many false-positively cued signals will potentially degrade the performance of detecting true-positive regions and increase the call-back rate in CAD environment. In this paper, we proposed a novel classification method for FP reduction, where the conventional 'hard' decision classifier is cascaded with a 'soft' decision classification with the objective to reduce false-positives in the cases with multiple FPs retained after the 'hard' decision classification. The 'soft' classification takes a competitive classification strategy in which only the 'best' ones are selected from the pre-classified suspicious regions as the true mass in each case. A neural network structure is designed to implement the proposed competitive classification. Comparative studies of FP reduction on a database of 79 images by a 'hard' decision classification and a combined 'hard'-'soft' classification method demonstrated the efficiency of the proposed classification strategy. For example, for the high FP sub-database which has only 31.7% of total images but accounts for 63.5% of whole FPs generated in single 'hard' classification, the FPs can be reduced for 56% (from 8.36 to 3.72 per image) by using the proposed method at the cost of 1% TP loss (from 69% to 68%) in whole database, while it can only be reduced for 27% (from 8.36 to 6.08 per image) by simply increasing the threshold of 'hard' classifier with a cost of TP loss as high as 14% (from 69% to 55%). On the average in whole database, the FP reduction by hybrid 'hard'-'soft' classification is 1.58 per image as compared to 1.11 by 'hard' classification at the TP costs described above. Because the cases with high dense tissue are of higher risk of cancer incidence and false-negative detection in mammogram screening, and usually generate more FPs in CAD detection, the method proposed in this paper will be very helpful in improving

  18. Suture Granuloma Showing False-Positive Findings on FDG-PET

    Directory of Open Access Journals (Sweden)

    Kohei Takahara

    2013-01-01

    Full Text Available We report a case of a 33-year-old male with a mixed germ-cell testicular tumor. Postoperative follow-up FDG-PET revealed concentration of FDG in the left inguinal area which is not tumor metastasis or local recurrence but suture reactivity granuloma. In this paper, we reviewed suture granulomas associated with false-positive findings on FDG-PET after surgery. If FDG-PET will be used more frequently in the future, it will be necessary to refrain from using silk thread in order to prevent any unnecessary surgery.

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

    International Nuclear Information System (INIS)

    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 for a false-positive indium-111 WBC scan

  20. Comparison of cumulative false-positive risk of screening mammography in the United States and Denmark

    DEFF Research Database (Denmark)

    Kemp Jacobsen, Katja; Abraham, Linn; Buist, Diana S M

    2015-01-01

    INTRODUCTION: In the United States (US), about one-half of women screened with annual mammography have at least one false-positive test after ten screens. The estimate for European women screened ten times biennially is much lower. We evaluate to what extent screening interval, mammogram type......, and statistical methods, can explain the reported differences. METHODS: We included all screens from women first screened at age 50-69 years in the US Breast Cancer Surveillance Consortium (BCSC) (n=99,455) between 1996-2010, and from two population-based mammography screening programs in Denmark (n=230,452 and n...

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

    Directory of Open Access Journals (Sweden)

    Van den Ende Jef

    2010-07-01

    Full Text Available Abstract 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.

  2. Reporting instructions significantly impact false positive rates when reading chest radiographs

    International Nuclear Information System (INIS)

    Robinson, John W.; Brennan, Patrick C.; Mello-Thoms, Claudia; Lewis, Sarah J.

    2016-01-01

    To determine the impact of specific reporting tasks on the performance of radiologists when reading chest radiographs. Ten experienced radiologists read a set of 40 postero-anterior (PA) chest radiographs: 21 nodule free and 19 with a proven solitary nodule. There were two reporting conditions: an unframed task (UFT) to report any abnormality and a framed task (FT) reporting only lung nodule/s. Jackknife free-response operating characteristic (JAFROC) figure of merit (FOM), specificity, location sensitivity and number of true positive (TP), false positive (FP), true negative (TN) and false negative (FN) decisions were used for analysis. JAFROC FOM for tasks showed a significant reduction in performance for framed tasks (P = 0.006) and an associated decrease in specificity (P = 0.011) but no alteration to the location sensitivity score. There was a significant increase in number of FP decisions made during framed versus unframed tasks for nodule-containing (P = 0.005) and nodule-free (P = 0.011) chest radiographs. No significant differences in TP were recorded. Radiologists report more FP decisions when given specific reporting instructions to search for nodules on chest radiographs. The relevance of clinical history supplied to radiologists is called into question and may induce a negative effect. (orig.)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  5. Empirical methods for controlling false positives and estimating confidence in ChIP-Seq peaks

    Directory of Open Access Journals (Sweden)

    Courdy Samir J

    2008-12-01

    Full Text Available Abstract Background High throughput signature sequencing holds many promises, one of which is the ready identification of in vivo transcription factor binding sites, histone modifications, changes in chromatin structure and patterns of DNA methylation across entire genomes. In these experiments, chromatin immunoprecipitation is used to enrich for particular DNA sequences of interest and signature sequencing is used to map the regions to the genome (ChIP-Seq. Elucidation of these sites of DNA-protein binding/modification are proving instrumental in reconstructing networks of gene regulation and chromatin remodelling that direct development, response to cellular perturbation, and neoplastic transformation. Results Here we present a package of algorithms and software that makes use of control input data to reduce false positives and estimate confidence in ChIP-Seq peaks. Several different methods were compared using two simulated spike-in datasets. Use of control input data and a normalized difference score were found to more than double the recovery of ChIP-Seq peaks at a 5% false discovery rate (FDR. Moreover, both a binomial p-value/q-value and an empirical FDR were found to predict the true FDR within 2–3 fold and are more reliable estimators of confidence than a global Poisson p-value. These methods were then used to reanalyze Johnson et al.'s neuron-restrictive silencer factor (NRSF ChIP-Seq data without relying on extensive qPCR validated NRSF sites and the presence of NRSF binding motifs for setting thresholds. Conclusion The methods developed and tested here show considerable promise for reducing false positives and estimating confidence in ChIP-Seq data without any prior knowledge of the chIP target. They are part of a larger open source package freely available from http://useq.sourceforge.net/.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  8. Using ELISPOT to expose false positive skin test conversion in tuberculosis contacts.

    Directory of Open Access Journals (Sweden)

    Philip C Hill

    2007-01-01

    Full Text Available Repeat tuberculin skin tests may be false positive due to boosting of waned immunity to past mycobacterial exposure. We evaluated whether an ELISPOT test could identify tuberculosis (TB contacts with boosting of immunity to non-tuberculous mycobacterial exposure.We conducted tuberculin and ELISPOT tests in 1665 TB contacts: 799 were tuberculin test negative and were offered a repeat test after three months. Those with tuberculin test conversion had an ELISPOT, chest X-ray and sputum analysis if appropriate. We compared converters with non-converters, assessed the probability of each of four combinations of ELISPOT results over the two time points and estimated boosting with adjustment for ELISPOT sensitivity and specificity. 704 (72% contacts had a repeat tuberculin test; 176 (25% had test conversion, which increased with exposure to a case (p = 0.002, increasing age (p = 0.0006 and BCG scar (p = 0.06. 114 tuberculin test converters had ELISPOT results: 16(14% were recruitment positive/follow-up positive, 9 (8% positive/negative, 34 (30% negative/positive, and 55 (48% were negative/negative. There was a significant non-linear effect of age for ELISPOT results in skin test converters (p = 0.038. Estimates of boosting ranged from 32%-41% of skin test converters with increasing age. Three converters were diagnosed with TB, two had ELISPOT results: both were positive, including one at recruitment.We estimate that approximately one third of tuberculin skin test conversion in Gambian TB case contacts is due to boosting of immunity to non-tuberculous mycobacterial exposure. Further longitudinal studies are required to confirm whether ELISPOT can reliably identify case contacts with tuberculin test conversion that would benefit most from prophylactic treatment.

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

    Science.gov (United States)

    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 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, fibroadenoma and papilloma for benign cases. We need to pay particular attention to the collection and assessment of aspirates for these histological types of breast disease. In particular, several

  10. A mode of error: Immunoglobulin binding protein (a subset of anti-citrullinated proteins can cause false positive tuberculosis test results in rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    Maria Greenwald

    2017-12-01

    Full Text Available Citrullinated Immunoglobulin Binding Protein (BiP is a newly described autoimmune target in rheumatoid arthritis (RA, one of many cyclic citrullinated peptides(CCP or ACPA. BiP is over-expressed in RA patients causing T cell expansion and increased interferon levels during incubation for the QuantiFERON-Gold tuberculosis test (QFT-G TB. The QFT-G TB has never been validated where interferon is increased by underlying disease, as for example RA.Of ACPA-positive RA patients (n = 126, we found a 13% false-positive TB test rate by QFT-G TB. Despite subsequent biologic therapy for 3 years of all 126 RA patients, none showed evidence of TB without INH. Most of the false-positive RA patients after treatment with biologic therapy reverted to a negative QFT-G test. False TB tests correlated with ACPA level (p < 0.02.Three healthy women without arthritis or TB exposure had negative QFT-G TB. In vitro, all three tested positive every time for TB correlating to the dose of BiP or anti-BiP added, at 2 ug/ml, 5 ug/ml, 10 ug/ml, and 20 ug/ml.BiP naturally found in the majority of ACPA-positive RA patients can result in a false positive QFT-G TB. Subsequent undertreatment of RA, if biologic therapy is withheld, and overtreatment of presumed latent TB may harm patients. Keywords: Tuberculosis, IGRA, Rheumatoid arthritis, Interferon, Anti-citrullinated peptide antibody (ACPA, Immunoglobulin binding protein (BiP

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

    Energy Technology Data Exchange (ETDEWEB)

    James, Conrad D.; Pohl, Kenneth Roy; Derzon, Mark Steven; McClain, Jaime; Achyuthan, Komandoor

    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 for 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.

  12. False positive reduction for pulmonary nodule detection using two-dimensional principal component analysis

    Science.gov (United States)

    Choi, Wook-Jin; Choi, Tae-Sun

    2009-08-01

    Pulmonary nodule detection is a binary classification problem. The main objective is to classify nodule from the lung computed tomography (CT) images. The intra class variability is mainly due to the grey-level variance, texture differences and shape. The purpose of this study is to develop a novel nodule detection method which is based on Two-dimensional Principal Component Analysis (2DPCA). We extract the futures using 2DPCA from nodule candidate images. Nodule candidates are classified using threshold. The proposed method reduces False Positive (FP) rate. We tested the proposed algorithm by using Lung Imaging Database Consortium (LIDC) database of National Cancer Institute (NCI). The experimental results demonstrate the effectiveness and efficiency of the proposed method. The proposed method achieved 85.11% detection rate with 1.13 FPs per scan.

  13. False Positive STEMI Activations in a Regional Network: Comprehensive Analysis and Clinical Impact. Results From the Catalonian Codi Infart Network.

    Science.gov (United States)

    Regueiro, Ander; Fernández-Rodríguez, Diego; Freixa, Xavier; Bosch, Xavier; Martín-Yuste, Victoria; Brugaletta, Salvatore; Roqué, Mercè; Sabaté, Manel; Masotti, Mónica

    2017-07-12

    ST-segment elevation myocardial infarction (STEMI) network activation by a noncardiologist reduces delay times but may increase the rate of false-positive STEMI diagnoses. We aimed to determine the prevalence, predictors, and clinical impact of false-positive activations within the Catalonian STEMI network (Codi Infart). From January 2010 through December 2011, all consecutive patients treated within the Codi Infart network were included. Code activations were classified as appropriate if they satisfied both electrocardiogram and clinical STEMI criteria. Appropriate activations were classified as false positives using 2 nonexclusive definitions: a) "angiographic" if a culprit coronary artery was not identified, and b) "clinical" if the discharge diagnosis was other than STEMI. In total, 5701 activations were included. Appropriate activation was performed in 87.8% of the episodes. The rate of angiographic false positives was 14.6%, while the rate of clinical false positives was 11.6%. Irrespective of the definition, female sex, left bundle branch block, and previous myocardial infarction were independent predictors of false-positive STEMI diagnoses. Using the clinical definition, hospitals without percutaneous coronary intervention and patients with complications during the first medical contact also had a false-positive STEMI diagnoses rate higher than the mean. In-hospital and 30-day mortality rates were similar for false-positive and true-positive STEMI patients after adjustment for possible confounders. False-positive STEMI diagnoses were frequent. Outcomes were similar for patients with a true-positive or false-positive STEMI diagnosis treated within a STEMI network. The presence of any modifiable predictors of a false-positive STEMI diagnosis warrants careful assessment to optimize the use of STEMI networks. Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  14. Computer-Aided Detection in Digital Mammography: False-Positive Marks and Their Reproducibility in Negative Mammograms

    International Nuclear Information System (INIS)

    Kim, Seung Ja; Moon, Woo Kyung; Cho, Nariya; Chang, Jung Min; Seong, Min Hyun

    2009-01-01

    Background: There are relatively few studies reporting the frequency of false-positive computer-aided detection (CAD) marks and their reproducibility in normal cases. Purpose: To evaluate retrospectively the false-positive mark rate of a CAD system and the reproducibility of false-positive marks in two sets of negative digital mammograms. Material and Methods: Two sets of negative digital mammograms were obtained in 360 women (mean age 57 years, range 30-76 years) with an approximate interval of 1 year (mean time 343.7 days), and a CAD system was applied. False-positive CAD marks and the reproducibility were determined. Results: Of the 360 patients, 252 (70.0%) and 240 (66.7%) patients had 1-7 CAD marks on the initial and second mammograms, respectively. The false-positive CAD mark rate was 1.5 (1.1 for masses and 0.4 for calcifications) and 1.4 (1.0 for masses and 0.4 for calcifications) per examination in the initial and second mammograms, respectively. The reproducibility of the false-positive CAD marks was 12.0% for both mass (81/680) and microcalcification (33/278) marks. Conclusion: False-positive CAD marks were seen in approximately 70% of normal cases. However, the reproducibility was very low. Radiologists must be familiar with the findings of false-positive CAD marks, since they are very common and can increase the recall rate in screening

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

    International Nuclear Information System (INIS)

    Fink-Bennett, D.

    1982-01-01

    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 revealed 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

  16. False positive localisation of C-11 methionine in a colloid nodule

    International Nuclear Information System (INIS)

    Mahajan, Sonia; Tripathi, Madhavi; Jaimini, Abhinav; Dinesh, Anant

    2011-01-01

    A 45-year-old female diagnosed with carcinoma of the left breast on histopathological examination underwent both 18 F-flourodeoxyglucose (FDG) and 11C-methionine (MET) positron emission tomography/computed tomography (PET/CT) as part of a protocol comparing the utility of these tracers for predicting a response to neoadjuvant chemotherapy in breast carcinoma. Abnormal FDG and MET accumulation was noted in the left breast primary, left axillary lymph nodes, and also in a well-defined nodule present in the left lobe of the thyroid gland. Keeping in mind the possibility of thyroid neoplasm/metastasis, the patient was referred for fine needle aspiration cytology (FNAC) from the thyroid nodule that revealed features of a simple colloid nodule. Focal thyroid lesions incidentally found on 18 F-FDG PET/CT have a high risk of thyroid malignancy. Non-specific accumulation of FDG in thyroid adenomas is also known. This case highlights a potential cause for false positive on C-11 MET PET/CT in colloid adenomas, which should be kept in mind while using this tracer for oncological indications

  17. Reduction of false positives by extracting fuzzy rules from data for polyp detection in CTC scans

    Science.gov (United States)

    Siddique, Musib M.; Zheng, Yalin; Yang, Xiaoyun; Beddoe, Gareth

    2008-03-01

    This paper presents an adaptive neural network based Fuzzy Inference System (ANFIS) to reduce the false positive (FP) rate of detected colonic polyps in Computed Tomography Colonography (CTC) scans. Extracted fuzzy rules establish linguistically interpretable relationships in the data that are easy to understand, validate, and extend. The system takes several features identified from regions extracted by a segmentation algorithm and decides whether the regions are true polyps. In the training phase, subtractive clustering is used to down-sample the negative regions in order to get balanced data. The rule extraction method is based on estimating clusters in the data using the subtractive clustering algorithm; each cluster obtained corresponds to a fuzzy rule that maps a region in the input space to an output class. After the number of rules and initial rule parameters are obtained by cluster estimation, the rule parameters are optimized using a hybrid learning algorithm which is a combination of least-squares estimation with back propagation. The evolved Sugeno-type FIS has been tested on a total of 129 scans with 99 polyps of sizes 5-15 mm by experienced radiologists. The results indicate that for 93% detection sensitivity (on polyps), the evolved FIS method is able to remove 88% of FPs generated by the segmentation algorithm leaving 7.5 FP per scan. The high sensitivity rate of our results show the promise of neuro-fuzzy classifiers as an aid for interpreting CTC examinations.

  18. Computerized detection of unruptured aneurysms in MRA images: reduction of false positives using anatomical location features

    Science.gov (United States)

    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.

  19. Limited agreement of independent RNAi screens for virus-required host genes owes more to false-negative than false-positive factors.

    Directory of Open Access Journals (Sweden)

    Linhui Hao

    Full Text Available 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.

  20. Reducing the false positive rate in the non-parametric analysis of molecular coevolution

    Directory of Open Access Journals (Sweden)

    O'Dea Shirley

    2008-04-01

    Full Text Available Abstract Background The strength of selective constraints operating on amino acid sites of proteins has a multifactorial nature. In fact, amino acid sites within proteins coevolve due to their functional and/or structural relationships. Different methods have been developed that attempt to account for the evolutionary dependencies between amino acid sites. Researchers have invested a significant effort to increase the sensitivity of such methods. However, the difficulty in disentangling functional co-dependencies from historical covariation has fuelled the scepticism over their power to detect biologically meaningful results. In addition, the biological parameters connecting linear sequence evolution to structure evolution remain elusive. For these reasons, most of the evolutionary studies aimed at identifying functional dependencies among protein domains have focused on the structural properties of proteins rather than on the information extracted from linear multiple sequence alignments (MSA. Non-parametric methods to detect coevolution have been reported to be especially susceptible to produce false positive results based on the properties of MSAs. However, no formal statistical analysis has been performed to definitively test the differential effects of these properties on the sensitivity of such methods. Results Here we test the effect that variations on the MSA properties have over the sensitivity of non-parametric methods to detect coevolution. We test the effect that the size of the MSA (number of sequences, mean pairwise amino acid distance per site and the strength of the coevolution signal have on the ability of non-parametric methods to detect coevolution. Our results indicate that all three factors have significant effects on the accuracy of non-parametric methods. Further, introducing statistical filters improves the sensitivity and increases the statistical power of the methods to detect functional coevolution. Statistical

  1. Factors influencing accuracy of referral and the likelihood of false positive referral by optometrists in Bradford, United Kingdom.

    Science.gov (United States)

    Davey, Christopher James; Scally, Andrew J; Green, Clare; Mitchell, Edwin S; Elliott, David B

    2016-01-01

    Levels of false positive referral to ophthalmology departments can be high. This study aimed to evaluate commonality between false positive referrals in order to find the factors which may influence referral accuracy. In 2007/08, a sample of 431 new Ophthalmology referrals from the catchment area of Bradford Royal Infirmary were retrospectively analysed. The proportion of false positive referrals generated by optometrists decreases with experience at a rate of 6.2% per year since registration (p<0.0001). Community services which involved further investigation done by the optometrist before directly referring to the hospital were 2.7 times less likely to refer false positively than other referral formats (p=0.007). Male optometrists were about half as likely to generate a false positive referral than females (OR=0.51, p=0.008) and as multiple/corporate practices in the Bradford area employ less experienced and more female staff, independent practices generate about half the number of false positive referrals (OR=0.52, p=0.005). Clinician experience has the greatest effect on referral accuracy although there is also a significant effect of gender with women tending to refer more false positives. This may be due to a different approach to patient care and possibly a greater sensitivity to litigation. The improved accuracy of community services (which often refer directly after further investigation) supports further growth of these schemes. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  2. Effect of radiologist experience on the risk of false-positive results in breast cancer screening programs

    International Nuclear Information System (INIS)

    Zubizarreta Alberdi, Raquel; Llanes, Ana B.F.; Ortega, Raquel Almazan; Exposito, Ruben Roman; Collado, Jose M.V.; Oliveres, Xavier Castells; Queiro Verdes, Teresa; Natal Ramos, Carmen; Sanz, Maria Ederra; Salas Trejo, Dolores

    2011-01-01

    To evaluate the effect of radiologist experience on the risk of false-positive results in population-based breast cancer screening programmes. We evaluated 1,440,384 single-read screening mammograms, corresponding to 471,112 women aged 45-69 years participating in four Spanish programmes between 1990 and 2006. The mammograms were interpreted by 72 radiologists. The overall percentage of false-positive results was 5.85% and that for false-positives resulting in an invasive procedure was 0.38%. Both the risk of false-positives overall and of false-positives leading to an invasive procedure significantly decreased (p 14,999 mammograms with respect to the reference category (<500). The risk of both categories of false-positives was also significantly reduced (p < 0.001) as radiologists' years of experience increased: OR 0.96 and OR 0.84, respectively, for 1 year's experience and OR 0.72 and OR 0.73, respectively, for more than 4 years' experience with regard to the category of <1 year's experience. Radiologist experience is a determining factor in the risk of a false-positive result in breast cancer screening. (orig.)

  3. Is the false-positive rate in mammography in North America too high?

    Science.gov (United States)

    Mothersill, Carmel E; Seymour, Colin B; McNeill, Fiona E

    2016-01-01

    The practice of investigating pathological abnormalities in the breasts of females who are asymptomatic is primarily employed using X-ray mammography. The importance of breast screening is reflected in the mortality-based benefits observed among females who are found to possess invasive breast carcinoma prior to the manifestation of clinical symptoms. It is estimated that population-based screening constitutes a 17% reduction in the breast cancer mortality rate among females affected by invasive breast carcinoma. In spite of the significant utility that screening confers in those affected by invasive cancer, limitations associated with screening manifest as potential harms affecting individuals who are free of invasive disease. Disease-free and benign tumour-bearing individuals who are subjected to diagnostic work-up following a screening examination constitute a population of cases referred to as false positives (FPs). This article discusses factors contributing to the FP rate in mammography and extends the discussion to an assessment of the consequences associated with FP reporting. We conclude that the mammography FP rate in North America is in excess based upon the observation of overtreatment of in situ lesions and the disproportionate distribution of detriment and benefit among the population of individuals recalled for diagnostic work-up subsequent to screening. To address the excessive incidence of FPs in mammography, we investigate solutions that may be employed to remediate the current status of the FP rate. Subsequently, it can be suggested that improvements in the breast-screening protocol, medical litigation risk, image interpretation software and the implementation of image acquisition modalities that overcome superimposition effects are promising solutions. PMID:27187600

  4. Common causes of false positive F18 FDG PET/CT scans in oncology

    Directory of Open Access Journals (Sweden)

    Kevin R. Carter

    2007-09-01

    Full Text Available PET/CT is a common imaging modality used in the evaluation of oncology patients. While being extremely sensitive to identifying sights of malignancy F18FDG is very non-specific. We attempted to provide a brief review of some of the more common processes that a nuclear radiology physician may encounter in daily clinical practice that could result in a false positive diagnosis with F18FDG PET/CT. A fundamental understanding of the limitations of this technology by the interpreting physician is necessary to avoid making inaccurate diagnosis and potentially limiting important treatments for our patients.PET/CT é uma modalidade de imagem usada para avaliação de pacientes oncológicos. Embora seja extremamente sensível para identificar sinais de malignidade, o F18FDG não é ainda muito específico. Nós buscamos mostrar uma breve revisão de alguns dos processos mais comuns que um médico nuclear pode encontrar na prática clínica diária que poderia resultar em um diagnóstico falso positivo com a F18FDG PET/CT. Uma melhor compreensão das limitações dessa tecnologia é necessária para que a interpretação pelo médico não possibiite diagnósticos imprecisos, que potencialmente podem limitar os tratamentos dos pacientes.

  5. ST-Segment Depression in Hyperventilation Indicates a False Positive Exercise Test in Patients with Mitral Valve Prolapse

    Directory of Open Access Journals (Sweden)

    Andreas P. Michaelides

    2010-01-01

    Full Text Available Objectives. Mitral valve prolapse (MVP is a known cause for false positive exercise test (ET. The purpose of this study was to establish additional electrocardiographic criteria to distinguish the false positive exercise results in patients with MVP. Methods. We studied 218 consecutive patients ( years, 103 males with MVP (according to echocardiographic study, and positive treadmill ET was performed due to multiple cardiovascular risk factors or angina-like symptoms. A coronary angiography was performed to detect coronary artery disease (CAD. Results. From 218 patients, 90 (group A presented with normal coronary arteries according to the angiography (false positive ET while the rest 128 (group B presented with CAD. ST-segment depression in hyperventilation phase was present in 54 patients of group A (60% while only in 14 patients of group B (11%, . Conclusions. Presence of ST-segment depression in hyperventilation phase favors a false positive ET in patients with MVP.

  6. On minimizing assignment errors and the trade-off between false positives and negatives in parentage analysis

    KAUST Repository

    Harrison, Hugo B.

    2013-11-04

    Genetic parentage analyses provide a practical means with which to identify parent-offspring relationships in the wild. In Harrison et al.\\'s study (2013a), we compare three methods of parentage analysis and showed that the number and diversity of microsatellite loci were the most important factors defining the accuracy of assignments. Our simulations revealed that an exclusion-Bayes theorem method was more susceptible to false-positive and false-negative assignments than other methods tested. Here, we analyse and discuss the trade-off between type I and type II errors in parentage analyses. We show that controlling for false-positive assignments, without reporting type II errors, can be misleading. Our findings illustrate the need to estimate and report both the rate of false-positive and false-negative assignments in parentage analyses. © 2013 John Wiley & Sons Ltd.

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

    Science.gov (United States)

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

    Science.gov (United States)

    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

  9. Data from Paper “False-Positive Psychology: Undisclosed Flexibility in Data Collection and Analysis Allows Presenting Anything as Significant”

    Directory of Open Access Journals (Sweden)

    Joseph P Simmons

    2014-02-01

    Full Text Available The data includes measures collected for the two experiments reported in “False-Positive Psychology” [1] where listening to a randomly assigned song made people feel younger (Study 1 or actually be younger (Study 2. These data are useful because they illustrate inflations of false positive rates due to flexibility in data collection, analysis, and reporting of results. Data are useful for educational purposes.

  10. The molecular mimicry and its possible role in origin of false-positive results in HCV-infection testing

    Directory of Open Access Journals (Sweden)

    Benkovskaya L. K.

    2013-09-01

    Full Text Available The main reason for the false positive results of the detection of antibodies to HCV is considered the unspecific binding of the blood serum immunoglobulins with the components of the test-systems’ immunosorbent, what is observed in various pathologies. When considering the issues of diagnosis, prevention and treatment of infectious diseases examined the impact of antigenic heterogeneity and molecular mimicry. With regarding to hepatitis C this phenomenon more illustrated in terms of pathogenesis, autoimmune, extrahepatic lesions. This does not exclude the influence of antigenic mimicry on the specificity of serological tests for anti-HCV detection. Aim. Estimation the frequency of false-positive reactions of anti-HCV testing in patients with chronic somatic diseases and assessment of the antigenic mimicry’s role in their occurrence. Methods. Total anti-HCV, antibodies to the single viruses’ protein, and false positive sera antibodies’ interaction with microbial origin combinations (mimicrins were determined by ELISA. Mimicrins were separated from the cultural medium after cultivation Staphylococcus aureus, Micobacterium tuberculosis and Candida albicans. Results. Upon detection of anti-HCV in patients with chronic pathologies detected a significant number of false-positive results are more likely in patients with diabetes and among healthy individuals – in pregnant women.The majorities of false positive sera interacted with mimicrins. Conclusions. The antigenic crossings over between mimicrins and antibodies in the structure of false positive sera must be considered during the evaluation of the specific diagnostics’ results in the persons with different pathologic states.

  11. Interference Helps to Equalize the Read Range and Reduce False Positives of Passive RFID Tags

    DEFF Research Database (Denmark)

    Krigslund, Rasmus; Popovski, Petar; Pedersen, Gert Frølund

    2012-01-01

    In various applications of RFID systems a reader should reliably get the ID of the tags that are within a bounded proximity region, termed the interrogation zone. This gives rise to two types of errors 1) False Negative Detections (FNDs), when tags within the intended interrogation zone cannot...... interference enables design of well-defined interrogation zones for passive RFID systems....

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

    International Nuclear Information System (INIS)

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

    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 gonadal 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

  13. Case report: false positive elevated serum-galactomannan levels after autologous hematopoietic stem cell transplantation caused by oral nutritional supplements.

    Science.gov (United States)

    Rachow, Tobias; Dornaus, Sebastian; Sayer, Herbert G; Hermann, Beate; Hochhaus, Andreas; von Lilienfeld-Toal, Marie

    2016-05-01

    Positive galactomannan tests in patients who underwent chemotherapy without any clinical signs of a fungal infection should lead the clinician to consideration of a false-positive test result. Oral nutritional supplements may be a cause, especially in the case of concomitant disturbance of the gastrointestinal mucosal barrier because of mucositis.

  14. Effect of radiologist experience on the risk of false-positive results in breast cancer screening programs

    Energy Technology Data Exchange (ETDEWEB)

    Zubizarreta Alberdi, Raquel [Galician Breast Cancer Screening Programme, Public Health and Planning Directorate, Health Office, Galicia (Spain); Edificio Administrativo da Conselleria de Sanidade, Servicio de Programas Poboacionais de Cribado, Direccion Xeral de Saude Publica e Planificacion, Santiago de Compostela, Galicia (Spain); Llanes, Ana B.F.; Ortega, Raquel Almazan [Galician Breast Cancer Screening Programme, Public Health and Planning Directorate, Health Office, Galicia (Spain); Exposito, Ruben Roman; Collado, Jose M.V.; Oliveres, Xavier Castells [Department of Epidemiology and Evaluation, Institut Municipal d' Investigacio Medica-Parc de Salut Mar. CIBERESP, Barcelona (Spain); Queiro Verdes, Teresa [Galician Agency for Health Technology Assessment, Public Health and Planning Directorate, Health Office, Galicia (Spain); Natal Ramos, Carmen [Principality of Asturias Breast Cancer Screening Programme, Principality of Asturias (Spain); Sanz, Maria Ederra [Public Health Institute, Navarra Breast Cancer Screening Programme, Pamplona (Spain); Salas Trejo, Dolores [General Directorate Public Health and Centre for Public Health Research (CSISP), Valencia Breast Cancer Screening Programme, Valencia (Spain)

    2011-10-15

    To evaluate the effect of radiologist experience on the risk of false-positive results in population-based breast cancer screening programmes. We evaluated 1,440,384 single-read screening mammograms, corresponding to 471,112 women aged 45-69 years participating in four Spanish programmes between 1990 and 2006. The mammograms were interpreted by 72 radiologists. The overall percentage of false-positive results was 5.85% and that for false-positives resulting in an invasive procedure was 0.38%. Both the risk of false-positives overall and of false-positives leading to an invasive procedure significantly decreased (p < 0.001) with greater reading volume in the previous year: OR 0.77 and OR 0.78, respectively, for a reading volume 500-1,999 mammograms and OR 0.59 and OR 0.60 for a reading volume of >14,999 mammograms with respect to the reference category (<500). The risk of both categories of false-positives was also significantly reduced (p < 0.001) as radiologists' years of experience increased: OR 0.96 and OR 0.84, respectively, for 1 year's experience and OR 0.72 and OR 0.73, respectively, for more than 4 years' experience with regard to the category of <1 year's experience. Radiologist experience is a determining factor in the risk of a false-positive result in breast cancer screening. (orig.)

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

    Science.gov (United States)

    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.

  16. Caprine and ovine Greek dairy products: The official German method generates false-positive results due to κ-casein gene polymorphism.

    Science.gov (United States)

    Tsartsianidou, V; Triantafillidou, D; Karaiskou, N; Tarantili, P; Triantafillidis, G; Georgakis, E; Triantafyllidis, A

    2017-05-01

    Caseins are widely used for species identification of dairy products. Isoelectric focusing (IEF) of para-κ-casein peptide is used as the official German method for the differentiation between caprine (isoform A) and ovine (isoform B) dairy products, based on their different isoelectric points. The discrimination between Greek goat and ewe dairy products using IEF has, however, been shown to be problematic because of the existence of the ewe isoform in milk from Greek indigenous dairy goats. This could be due to nucleotide polymorphisms within the goat κ-casein gene of Greek indigenous breeds, which alter the isoelectric point of the para-κ-casein peptide and lead to false positive results. Previous DNA analysis of the goat κ-casein gene has shown high levels of polymorphism; however, no such information is available for Greek indigenous dairy goats. Therefore, 87 indigenous dairy goats were sequenced at exon IV of κ-casein gene. In total, 9 polymorphic sites were detected. Three nonsynonymous point mutations were identified, which change the isoelectric point of the goat para-κ-casein peptide so that it appears identical to that of the ewe peptide. Ten composite genotypes were reconstructed and 6 of them included the problematic point mutations. For the verification of genetic results, IEF was carried out. Both goat and ewe patterns appeared in the problematic genotypes. The frequency of these genotypes could be characterized as moderate (0.23) to high (0.60) within Greek indigenous breeds. However, this is not an issue restricted to Greece, as such genotypes have been detected in various non-Greek goat breeds. In conclusion, IEF based on the official German method is certainly inappropriate for ovine and caprine discrimination concerning Greek dairy goat products, and consequently a new method should be established. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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

  18. Prospective assessment of the false positive rate of the Australian snake venom detection kit in healthy human samples.

    Science.gov (United States)

    Nimorakiotakis, Vasilios Bill; Winkel, Kenneth D

    2016-03-01

    The Snake Venom Detection Kit (SVDK; bioCSL Pty Ltd, Australia) distinguishes venom from the five most medically significant snake immunotypes found in Australia. This study assesses the rate of false positives that, by definition, refers to a positive assay finding in a sample from someone who has not been bitten by a venomous snake. Control unbroken skin swabs, simulated bite swabs and urine specimens were collected from 61 healthy adult volunteers [33 males and 28 females] for assessment. In all controls, simulated bite site and urine samples [a total of 183 tests], the positive control well reacted strongly within one minute and no test wells reacted during the ten minute incubation period. However, in two urine tests, the negative control well gave a positive reaction (indicating an uninterpretable test). A 95% confidence interval for the false positive rate, on a per-patient rate, derived from the findings of this study, would extend from 0% to 6% and, on a per-test basis, it would be 0-2%. It appears to be a very low incidence (0-6%) of intrinsic true false positives for the SVDK. The clinical impresssion of a high SVDK false positive rate may be mostly related to operator error. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  19. False-positive Papanicolaou (PAP) test rates in the College of American Pathologists PAP education and PAP proficiency test programs: evaluation of false-positive responses of high-grade squamous intraepithelial lesion or cancer to a negative reference diagnosis.

    Science.gov (United States)

    Crothers, Barbara A; Booth, Christine Noga; Darragh, Teresa Marie; Zhao, Chengquan; Souers, Rhona J; Thomas, Nicole; Moriarty, Ann T

    2014-05-01

    In cytology proficiency testing (PT), participants fail for incorrectly interpreting a high-grade squamous intraepithelial lesion or cancer (HSIL+) Papanicolaou test result as negative. This penalty may lead to a false-positive interpretation of negative slides as HSIL+ to avoid failure. To investigate factors related to false-positive responses in a PT versus an educational environment. We analyzed 420,079 responses from 9414 validated negative reference slides in the College of American Pathologists Interlaboratory Comparison Program in Gynecologic Cytopathology (PAP Education) and compared them with responses from the Gynecologic Cytology Proficiency Testing Program for the percentage of false-positive (HSIL+) interpretations in each of 7 negative subcategories. We evaluated the influence of preparation type (ThinPrep, SurePath, and conventional Papanicolaou test), participant type (pathologist or cytotechnologist), and program time interval (preproficiency test or PT) on a false-positive response. Reference diagnosis and participant type, but not preparation type, were statistically correlated to false-positive responses. The interaction between program time interval and participant type was also significant. Pathologists had higher rates of false-positive results on preproficiency test (1.2% [800 of 68,690]) than they did on PT (0.8% [993 of 129,857]). Cytotechnologists had no differences between program time intervals (preproficiency, 0.9% [515 of 63,281] versus PT, 1.0 [1231 of 121,621]; P = .91). Negative subcategories frequently mistaken for HSIL+ were reparative changes (4.7% [427 of 9069]), atrophic vaginitis (1.8% [18 of 987]), and negative for intraepithelial lesion or malignancy (1.2% [2143 of 178,651]), but during PT, false-positive rates were significantly increased only for the negative for intraepithelial lesion or malignancy and herpes simplex virus (P Testing Program than they did in PAP Education, but participants were more likely to report a

  20. False positives and false negatives measure less than 0.001% in labeling ssDNA with osmium tetroxide 2,2’-bipyridine

    Directory of Open Access Journals (Sweden)

    Anastassia Kanavarioti

    2016-10-01

    Full Text Available Osmium tetroxide 2,2’-bipyridine (OsBp is known to react with pyrimidines in ssDNA and preferentially label deoxythymine (T over deoxycytosine (C. The product, osmylated DNA, was proposed as a surrogate for nanopore-based DNA sequencing due to OsBp’s “perfect” label attributes. Osmylated deoxyoligos translocate unassisted and measurably slow via sub-2 nm SiN solid-state nanopores, as well as via the alpha-hemolysin (α-HL pore. Both nanopores discriminate clearly between osmylated and intact nucleobase; α-HL was also shown to discriminate between osmylated T and osmylated C. Experiments presented here confirm that the kinetics of osmylation are comparable for short oligos and long ssDNA and show that pyrimidine osmylation is practically complete in two hours at room temperature with less than 15 mM OsBp. Under the proposed labeling conditions: deoxyoligo backbone degradation measures less than 1/1,000,000; false positives such as osmylated deoxyadenine (A and osmylated deoxyguanine (G measure less than 1/100,000; false negatives, i.e., unosmylated C measure less than 1/10,000; and unosmylated T must measure substantially lower than 1/10,000 due to the 27-fold higher reactivity of T compared to C. However, osmylated C undergoes degradation that amounts to about 1–2% for the duration of the labeling protocol. This degradation may be further characterized, possibly suppressed, and the properties of the degradation products via nanopore translocation can be evaluated to assure base calling quality in a DNA sequencing effort.

  1. Up in Smoke: Uncovering a Lack of Evidence for Proton Pump Inhibitors as a Source of Tetrahydrocannibol Immunoassay False Positives.

    Science.gov (United States)

    Powers, Jennifer L; Rasmussen, Natalie N; Hurst, Dow; Strathmann, Frederick G

    2017-11-08

    It is recommended that positives in immunoassay drug screens be followed up with more specific confirmatory testing. The drug package insert for pantoprazole mentions reports of false-positive urine screening tests for tetrahydrocannabinol in patients receiving proton pump inhibitors, but no method details or data are given, referenced, or found in literature searches. Thus, we investigated this using our laboratory's assay. A spiked sample and samples from 32 patients taking a proton pump inhibitor were analyzed using the EMIT II Plus Cannabinoid assay with a 20 ng/mL cutoff. Additionally, we examined urine samples from 50 patients with false-positive or low-positive screens for evidence of a proton pump inhibitor. To determine whether O-desmethyl pantoprazole sulfate, the major metabolite, shares any structural or electrostatic similarity to suggest a basis for cross-reactivity in the immunoassay, we used computational techniques for analyses. Molecular electrostatic potential energy (MEP) maps were calculated for the global minimum conformers, and the maximum common substructure Tanimoto similarity was calculated for the modeled compounds. Neither the spiked sample nor the patient samples were found to screen positive. None of the false-positive or low-positive screens were found to contain a proton pump inhibitor. Computational studies showed very little similarity in shape or electrostatics between the two molecules. We find no supporting evidence of pantoprazole as the cause of false positives in the EMIT II Plus Cannabinoid assay and caution the use of proton pump inhibitors as an explanation for tetrahydrocannabinol immunoassay false positives. © 2017 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

  2. Cumulative probability of false-positive recall or biopsy recommendation after 10 years of screening mammography: a cohort study.

    Science.gov (United States)

    Hubbard, Rebecca A; Kerlikowske, Karla; Flowers, Chris I; Yankaskas, Bonnie C; Zhu, Weiwei; Miglioretti, Diana L

    2011-10-18

    False-positive mammography results are common. Biennial screening may decrease the cumulative probability of false-positive results across many years of repeated screening but could also delay cancer diagnosis. To compare the cumulative probability of false-positive results and the stage distribution of incident breast cancer after 10 years of annual or biennial screening mammography. Prospective cohort study. 7 mammography registries in the National Cancer Institute-funded Breast Cancer Surveillance Consortium. 169,456 women who underwent first screening mammography at age 40 to 59 years between 1994 and 2006 and 4492 women with incident invasive breast cancer diagnosed between 1996 and 2006. False-positive recalls and biopsy recommendations stage distribution of incident breast cancer. False-positive recall probability was 16.3% at first and 9.6% at subsequent mammography. Probability of false-positive biopsy recommendation was 2.5% at first and 1.0% at subsequent examinations. Availability of comparison mammograms halved the odds of a false-positive recall (adjusted odds ratio, 0.50 [95% CI, 0.45 to 0.56]). When screening began at age 40 years, the cumulative probability of a woman receiving at least 1 false-positive recall after 10 years was 61.3% (CI, 59.4% to 63.1%) with annual and 41.6% (CI, 40.6% to 42.5%) with biennial screening. Cumulative probability of false-positive biopsy recommendation was 7.0% (CI, 6.1% to 7.8%) with annual and 4.8% (CI, 4.4% to 5.2%) with biennial screening. Estimates were similar when screening began at age 50 years. A non-statistically significant increase in the proportion of late-stage cancers was observed with biennial compared with annual screening (absolute increases, 3.3 percentage points [CI, -1.1 to 7.8 percentage points] for women age 40 to 49 years and 2.3 percentage points [CI, -1.0 to 5.7 percentage points] for women age 50 to 59 years) among women with incident breast cancer. Few women underwent screening over the

  3. False-positive findings in mammography screening induces short-term distress - breast cancer-specific concern prevails longer

    DEFF Research Database (Denmark)

    Aro, A R; Pilvikki Absetz, S; van Elderen, T M

    2000-01-01

    -ups at 2 and 12 months postscreening. At 2 months, there was a moderate multivariate effect of group on distress; and intrusive thinking and worry about breast cancer, in particular, were most frequent amongst the false positives. Intrusive thinking still prevailed at 12 months, in addition to a higher...... findings (n=1407), false-positive findings (n=492) and referents from outside the screening programme (n=1718, age 48-49 years). Distress was measured as illness worry, anxiety, depression, cancer beliefs and early detection behaviour. Measurements were one month before screening invitation with follow...... perceived breast cancer risk and susceptibility. Distress related to screening and false-positive findings seems to be moderate, but prevailing cancer-specific concerns call for improvements in screening programmes....

  4. A false-positive detection bias as a function of state and trait schizotypy in interaction with intelligence

    Directory of Open Access Journals (Sweden)

    Phillip eGrant

    2014-09-01

    Full Text Available Hallucinatory experiences are by far not limited to patients with clinical psychosis. A number of internal and external factors may bring about such experiences in healthy individuals, whereby the personality trait of (positive schizotypy is a major mediator of individual differences. Psychotic experiences are defined as associating abnormal meaning to real but objectively irrelevant perceptions. Especially the ambiguity of a stimulus correlates positively with the likelihood of abnormal interpretation, and intelligence is believed to have an important influence and act as protective against clinical psychosis in highly schizotypic individuals.In this study we presented 131 healthy participants with 216 15-letter strings containing either a word, a non-word or only random letters and asked them to report, whether or not they believed to have seen a word. The aim was to replicate findings that participants with high values in positive schizotypy on the trait-level make more false-positive errors and assess the role of stimulus-ambiguity and verbal intelligence. Additionally, we wanted to examine whether the same effect could be shown for indices of state schizotypy.Our results support findings that both state and trait positive schizotypy explain significant variance in seeing things that are not there and that the properties of individual stimuli have additional strong effects on the false-positive hit rates. Finally, we found that verbal intelligence and positive schizotypy interact with stimulus-ambiguity in the production of false-positive perceptions.

  5. A false-positive detection bias as a function of state and trait schizotypy in interaction with intelligence.

    Science.gov (United States)

    Grant, Phillip; Balser, Mona; Munk, Aisha Judith Leila; Linder, Jens; Hennig, Juergen

    2014-01-01

    Hallucinatory experiences are by far not limited to patients with clinical psychosis. A number of internal and external factors may bring about such experiences in healthy individuals, whereby the personality trait of (positive) schizotypy is a major mediator of individual differences. Psychotic experiences are defined as associating abnormal meaning to real but objectively irrelevant perceptions. Especially, the ambiguity of a stimulus correlates positively with the likelihood of abnormal interpretation, and intelligence is believed to have an important influence and act as protective against clinical psychosis in highly schizotypic individuals. In this study, we presented 131 healthy participants with 216 15-letter strings containing either a word, a non-word, or only random letters and asked them to report, whether or not they believed to have seen a word. The aim was to replicate findings that participants with high values in positive schizotypy on the trait-level make more false-positive errors and assess the role of stimulus-ambiguity and verbal intelligence. Additionally, we wanted to examine whether the same effect could be shown for indices of state schizotypy. Our results support findings that both state and trait positive schizotypy explain significant variance in "seeing things that are not there" and that the properties of individual stimuli have additional strong effects on the false-positive hit rates. Finally, we found that verbal intelligence and positive schizotypy interact with stimulus-ambiguity in the production of false-positive perceptions.

  6. Way forward in case of a false positive in vitro genotoxicity result for a cosmetic substance?

    Science.gov (United States)

    Doktorova, Tatyana Y; Ates, Gamze; Vinken, Mathieu; Vanhaecke, Tamara; Rogiers, Vera

    2014-02-01

    The currently used regulatory in vitro mutagenicity/genotoxicity test battery has a high sensitivity for detecting genotoxicants, but it suffers from a large number of irrelevant positive results (i.e. low specificity) thereby imposing the need for additional follow-up by in vitro and/or in vivo genotoxicity tests. This could have a major impact on the cosmetic industry in Europe, seen the imposed animal testing and marketing bans on cosmetics and their ingredients. Afflicted, but safe substances could therefore be lost. Using the example of triclosan, a cosmetic preservative, we describe here the potential applicability of a human toxicogenomics-based in vitro assay as a potential mechanistically based follow-up test for positive in vitro genotoxicity results. Triclosan shows a positive in vitro chromosomal aberration test, but is negative during in vivo follow-up tests. Toxicogenomics analysis unequivocally shows that triclosan is identified as a compound acting through non-DNA reactive mechanisms. This proof-of-principle study illustrates the potential of genome-wide transcriptomics data in combination with in vitro experimentation as a possible weight-of-evidence follow-up approach for de-risking a positive outcome in a standard mutagenicity/genotoxicity battery. As such a substantial number of cosmetic compounds wrongly identified as genotoxicants could be saved for the future. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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 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

  8. False Advertising

    OpenAIRE

    Rhodes, Andrew; Wilson, Chris M

    2015-01-01

    There is widespread evidence that some firms use false advertising to overstate the value of their products. We consider a model in which a policymaker is able to punish such false claims. We characterize an equilibrium where false advertising actively influences rational buyers, and analyze the effects of policy under different welfare objectives. We establish precise conditions where policy optimally permits a positive level of false advertising, and show how these conditions vary intuitive...

  9. A Case of False-Positive Mycobacterium tuberculosis Caused by Mycobacterium celatum

    OpenAIRE

    Gildeh, Edward; Abdel-Rahman, Zaid; Sengupta, Ruchira; Johnson, Laura

    2016-01-01

    Mycobacterium celatum is a nontuberculous mycobacterium shown to cause symptoms similar to pulmonary M. tuberculosis. Certain strains have been shown to cross-react with the probes used to detect M. tuberculosis, making this a diagnostic challenge. We present a 56-year-old gentleman who developed signs and symptoms of lung infection with computed tomography scan of the chest showing right lung apex cavitation. Serial sputum samples were positive for acid-fast bacilli and nucleic acid amplific...

  10. Internal Impingement of the Shoulder: A Risk of False Positive Test Outcomes in External Impingement Tests?

    Directory of Open Access Journals (Sweden)

    Tim Leschinger

    2017-01-01

    Full Text Available Background. External impingement tests are considered as being particularly reliable for identifying subacromial and coracoid shoulder impingement mechanisms. The purpose of the present study was to evaluate if these tests are likely to provoke an internal shoulder impingement mechanism which, in cases of a pathologic condition, can lead to a positive test result. Method. In 37 subjects, the mechanical contact between the glenoid rim and the rotator cuff (RC was measured quantitatively and qualitatively in external impingement test positions using an open MRI system. Results. Mechanical contact of the supraspinatus with the posterosuperior glenoid was present in 30 subjects in the Neer test. In the Hawkins test, the subscapularis was in contact with the anterosuperior glenoid in 33 subjects and the supraspinatus in 18. In the horizontal impingement test, anterosuperior contact of the supraspinatus with the glenoid was identified in 35 subjects. Conclusion. The Neer, Hawkins, and horizontal impingement tests are likely to provoke the mechanism of an internal shoulder impingement. A posterosuperior internal impingement mechanism is being provoked predominately in the Neer test. The Hawkins test narrows the distance between the insertions of the subscapularis and supraspinatus and the anterosuperior labrum, which leads to an anterosuperior impingement mechanism.

  11. A Case of False-Positive Mycobacterium tuberculosis Caused by Mycobacterium celatum

    Directory of Open Access Journals (Sweden)

    Edward Gildeh

    2016-01-01

    Full Text Available Mycobacterium celatum is a nontuberculous mycobacterium shown to cause symptoms similar to pulmonary M. tuberculosis. Certain strains have been shown to cross-react with the probes used to detect M. tuberculosis, making this a diagnostic challenge. We present a 56-year-old gentleman who developed signs and symptoms of lung infection with computed tomography scan of the chest showing right lung apex cavitation. Serial sputum samples were positive for acid-fast bacilli and nucleic acid amplification testing identified M. tuberculosis ribosomal RNA, resulting in treatment initiation. Further testing with high performance liquid chromatography showed a pattern consistent with M. celatum. This case illustrates the potential for M. celatum to mimic M. tuberculosis in both its clinical history and laboratory testing due to the identical oligonucleotide sequence contained in both. An increasing number of case reports suggest that early reliable differentiation could reduce unnecessary treatment and public health intervention associated with misdiagnosed tuberculosis.

  12. PEPTIDE SOLUBILITY, STRUCTURE AND CHARGE POSITION EFFECT ON ADSORPTION BY ALUMINIUM HYDROXIDE

    Directory of Open Access Journals (Sweden)

    Mary Trujillo

    2008-04-01

    Full Text Available Solubility, structure and position of charges in a peptide antigen sequence can be mentioned as being amongst the basic features of adsorption. In order to study their effect on adsorption, seven analogue series were synthesized from a MSP-1 peptide sequence by systematically replacing each one of the positions in the peptide sequence by aspartic acid, glutamic acid, serine, alanine, asparagine, glutamine or lysine. Such modifications in analogue peptide sequences showed a non-regular tendency regarding solubility and adsorption data. Aspartic acid and Glutamic acid analogue series showed great improvements in adsorption, especially in peptides where Lysine in position 6 and Arginine in position 13 were replaced. Solubility of position 5 analogue was greater than the position 6 analogue in Aspartic acid series; however, the position 6 analogue showed best adsorption results whilst the Aspartic acid in position 5 analogue showed no adsorption in the same conditions. Nuclear Magnetic Resonance structural analysis revealed differences in the -helical structureextension between these analogues. The Aspartic acid in position 6, located in the polar side of the helix, may allow this analogueto fit better onto the adsorption regions suggesting that the local electrostatic charge is responsible for this behavior.

  13. Controlling the false positive rate in fuzzy clustering using randomization: application to fMRI activation detection.

    Science.gov (United States)

    Jahanian, Hesamoddin; Hossein-Zadeh, Gholam-Ali; Soltanian-Zadeh, Hamid; Ardekani, Babak A

    2004-06-01

    Despite its potential advantages for fMRI analysis, fuzzy C-means (FCM) clustering suffers from limitations such as the need for a priori knowledge of the number of clusters, and unknown statistical significance and instability of the results. We propose a randomization-based method to control the false-positive rate and estimate statistical significance of the FCM results. Using this novel approach, we develop an fMRI activation detection method. The ability of the method in controlling the false-positive rate is shown by analysis of false positives in activation maps of resting-state fMRI data. Controlling the false-positive rate in FCM allows comparison of different fuzzy clustering methods, using different feature spaces, to other fMRI detection methods. In this article, using simulation and real fMRI data, we compare a novel feature space that takes the variability of the hemodynamic response function into account (HRF-based feature space) to the conventional cross-correlation analysis and FCM using the cross-correlation feature space. In both cases, the HRF-based feature space provides a greater sensitivity compared to the cross-correlation feature space and conventional cross-correlation analysis. Application of the proposed method to finger-tapping fMRI data, using HRF-based feature space, detected activation in sub-cortical regions, whereas both of the FCM with cross-correlation feature space and the conventional cross-correlation method failed to detect them.

  14. A False Positive I-131 Metastatic Survey Caused by Radioactive Iodine Uptake by a Benign Thymic Cyst

    Directory of Open Access Journals (Sweden)

    Avneet K. Singh

    2017-01-01

    Full Text Available Thyroid carcinoma is the most common endocrine malignancy in the United States with increasing incidence and diagnosis but stable mortality. Differentiated thyroid cancer rarely presents with distant metastases and is associated with a low risk of morbidity and mortality. Despite this, current protocols recommend remnant ablation with radioactive iodine and evaluation for local and distant metastasis in some patients with higher risk disease. There are several case reports of false positive results of metastatic surveys that are either normal physiologic variants or other pathological findings. Most false positive findings are associated with tissue that has physiologic increased uptake of I-131, such as breast tissue or lung tissue; pathological findings such as thymic cysts are also known to have increased uptake. Our case describes a rare finding of a thymic cyst found on a false positive I-131 metastatic survey. The patient was taken for surgical excision and the final pathology was a benign thymic cyst. Given that pulmonary metastases of differentiated thyroid cancer are rare, thymic cysts, though also rare, must be part of the differential diagnosis for false positive findings on an I-131 survey.

  15. Trisomy 13 or 18 (mosaicism) in first trimester cytotrophoblast cells: false-positive results in 11 out of 51 cases

    NARCIS (Netherlands)

    Schuring-Blom, G. Heleen; Boer, Kees; Knegt, Alida C.; Verjaal, Marjan; Leschot, Nico J.

    2002-01-01

    Objective: The finding of full or mosaic trisomy 13 or IS in first trimester chorionic villus sampling (CVS) may be a false-positive result. This report provides incidence and outcome information that may be helpful in counselling individual patients and in choosing adequate follow-up. Study design:

  16. Reduction of false positives in the detection of architectural distortion in mammograms by using a geometrically constrained phase portrait model

    International Nuclear Information System (INIS)

    Ayres, Fabio J.; Rangayyan, Rangaraj M.

    2007-01-01

    Objective One of the commonly missed signs of breast cancer is architectural distortion. We have developed techniques for the detection of architectural distortion in mammograms, based on the analysis of oriented texture through the application of Gabor filters and a linear phase portrait model. In this paper, we propose constraining the shape of the general phase portrait model as a means to reduce the false-positive rate in the detection of architectural distortion. Material and methods The methods were tested with one set of 19 cases of architectural distortion and 41 normal mammograms, and with another set of 37 cases of architectural distortion. Results Sensitivity rates of 84% with 4.5 false positives per image and 81% with 10 false positives per image were obtained for the two sets of images. Conclusion The adoption of a constrained phase portrait model with a symmetric matrix and the incorporation of its condition number in the analysis resulted in a reduction in the false-positive rate in the detection of architectural distortion. The proposed techniques, dedicated for the detection and localization of architectural distortion, should lead to efficient detection of early signs of breast cancer. (orig.)

  17. Evaluation of Patients with an Apparent False Positive Stool DNA Test: The Role of Repeat Stool DNA Testing.

    Science.gov (United States)

    Cooper, Gregory S; Markowitz, Sanford D; Chen, Zhengyi; Tuck, Missy; Willis, Joseph E; Berger, Barry M; Brenner, Dean E; Li, Li

    2018-03-07

    There is uncertainty as to the appropriate follow-up of patients who test positive on multimarker stool DNA (sDNA) testing and have a colonoscopy without neoplasia. To determine the prevalence of missed colonic or occult upper gastrointestinal neoplasia in patients with an apparent false positive sDNA. We prospectively identified 30 patients who tested positive with a commercially available sDNA followed by colonoscopy without neoplastic lesions. Patients were invited to undergo repeat sDNA at 11-29 months after the initial test followed by repeat colonoscopy and upper endoscopy. We determined the presence of neoplastic lesions on repeat evaluation stratified by results of repeat sDNA. Twelve patients were restudied. Seven patients had a negative second sDNA test and a normal second colonoscopy and upper endoscopy. In contrast, 5 of 12 subjects had a persistently positive second sDNA test, and 3 had positive findings, including a 3-cm sessile transverse colon adenoma with high-grade dysplasia, a 2-cm right colon sessile serrated adenoma with dysplasia, and a nonadvanced colon adenoma (p = 0.045). These corresponded to a positive predictive value of 0.60 (95% CI 0.17-1.00) and a negative predictive value of 1.00 (95% CI 1.00-1.00) for the second sDNA test. In addition, the medical records of all 30 subjects with apparent false positive testing were reviewed and no documented cases of malignant tumors were recorded. Repeat positive sDNA testing may identify a subset of patients with missed or occult colorectal neoplasia after negative colonoscopy for an initially positive sDNA. High-quality colonoscopy with careful attention to the right colon in patients with positive sDNA is critically important and may avoid false negative colonoscopy.

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

    Science.gov (United States)

    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.

  19. The evaluation of possible false positives with detergents when performing amylase serological testing on clothing.

    Science.gov (United States)

    Feia, Andrea; Novroski, Nicole

    2013-01-01

    For almost 40 years, detergent companies have been adding enzymes such as amylases to their products as an effective method of breaking down tough stains created by polysaccharides and proteins. The possibility that α-amylases present in common household laundry detergents may contribute to the positive detection of α-amylase on evidentiary samples during forensic presumptive screening procedures is a potential problem that has not yet been investigated. To determine whether α-amylase detection is possible following routine laundering, five different fabrics were laundered in a variety of detergents, and presumptive testing using RSID(™)-Saliva and Phadebas(®) Amylase Test was conducted. Our results demonstrate that clothing laundered in detergents known to contain enzymes does not retain any detectable levels of α-amylase following a typical wash cycle. We also show that, unlike laundered clothing, undiluted detergents do contain detectable levels of α-amylase; however, these findings were only observed using the Phadebas(®) Amylase Test. © 2012 American Academy of Forensic Sciences.

  20. Distinguishing binders from false positives by free energy calculations: fragment screening against the flap site of HIV protease.

    Science.gov (United States)

    Deng, Nanjie; Forli, Stefano; He, Peng; Perryman, Alex; Wickstrom, Lauren; Vijayan, R S K; Tiefenbrunn, Theresa; Stout, David; Gallicchio, Emilio; Olson, Arthur J; Levy, Ronald M

    2015-01-22

    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.

  1. False-positive pregnancy test after transfusion of solvent/detergent-treated plasma.

    Science.gov (United States)

    Jilma-Stohlawetz, Petra; Wreford-Bush, Tim; Mills, Francesca; Davidson, Fiona; Kursten, Friedrich W; Jilma, Bernd; Birchall, Janet

    2017-12-01

    The transmission of pathogens, antibodies, and proteins is a possible consequence of blood product transfusion. A female patient had an unexpected positive serum β-human chorionic gonadotropin result, indicative of pregnancy, after she had received a transfusion with 1 unit of platelet concentrate, 4 units of red blood cells, and 4 units of pooled solvent/detergent-treated plasma (Octaplas). To investigate the possibility of passive transfusion of β-human chorionic gonadotropin from the plasma transfusion, one additional unit from the same batch was thawed and analyzed. To validate the β-human chorionic gonadotropin assay for use in solvent/detergent-treated plasma and to investigate any interference in the assay, dilution experiments were performed using the implicated plasma batch diluted with male and non-pregnant female sera. Also, plasma from a known pregnant woman was diluted with Octaplas (tested negative for β-human chorionic gonadotropin) and with a male serum to validate the assay for use in solvent/detergent-treated plasma. The implicated solvent/detergent-treated plasma had a mean β-human chorionic gonadotropin level of 91.5 mIU/mL. Results from the dilution experiments revealed an excellent correlation (r > 0.99) between β-human chorionic gonadotropin measurement in solvent/detergent-treated plasma and male serum and no over or under recovery of the expected results. Further measurements of β-human chorionic gonadotropin levels in the female recipient revealed an estimated half-life of 6 hours. This case demonstrates the importance of considering the possibility of passive transmission of analytes to a patient from the transfusion of blood products. Furthermore, the measurement of β-human chorionic gonadotropin is valid in solvent/detergent-treated plasma using a Roche Cobas analyzer. © 2017 AABB.

  2. AhR/Arnt:XRE interaction: Turning false negatives into true positives in the modified yeast one-hybrid assay

    Science.gov (United States)

    Chen, Gang; Shin, Jumi A.

    2009-01-01

    Given the frequent occurrence of false negatives in yeast genetic assays, it is both interesting and practical to address the possible mechanisms of false negatives and, more important, to turn false negatives into true positives. We recently developed a modified yeast one-hybrid system (MY1H) useful for investigation of simultaneous protein–protein and protein:DNA interactions in vivo. We coexpressed the basic helix–loop–helix/Per-Arnt-Sim (bHLH/PAS) domains of aryl hydrocarbon receptor (AhR) and aryl hydrocarbon receptor nuclear translocator (Arnt)—namely NAhR and NArnt, respectively—which are known to form heterodimers and bind the cognate xenobiotic response element (XRE) sequence both in vitro and in vivo, as a positive control in the study of XRE-binding proteins in the MY1H system. However, we observed negative results, that is, no positive signal detected from binding of the NAhR/NArnt heterodimer and XRE site. We demonstrate that by increasing the copy number of XRE sites integrated into the yeast genome and using double GAL4 activation domains, the NAhR/NArnt heterodimer forms and specifically binds the cognate XRE sequence, an interaction that is now clearly detectable in the MY1H system. This methodology may be helpful in troubleshooting and correcting false negatives that arise from unproductive transcription in yeast genetic assays. PMID:18722998

  3. False-positive 18-fluorodeoxyglucose positron emission tomography–computed tomography (FDG PET/CT scans mimicking malignancies

    Directory of Open Access Journals (Sweden)

    Zehra Yasar

    2015-02-01

    Full Text Available Aim 18-Fluorodeoxyglucose (FDG positron emission tomography–computed tomography (PET/CT is an imaging modality that is often used to help differentiate benign from malignant pulmonary lesions and it has been shown to be more efficacious than conventional chest computed tomography (CT. However, some benign lesions may also show increased metabolic activity which can lead to false-positive PET findings. We aim to illustrate false positive findings of PET scan that simulate lung cancer in a variety of diseases. Methods Patients referred to Yedikule Chest Diseases and Surgery Teaching and Research Hospital with increased FDG uptake for which histological results were available over a 2-year period (2013-2014 were reviewed. Seven patients with false-positive PET/CT findings were reported in this study. Results The majority of lesions showing increased metabolic activity were due to malignant diseases. However, increased 18 F-FDG uptake was also seen in benign lesions such as active pulmonary inflammation or infection, granulomatous processes and fibrotic lesions. Conclusion. The integration of clinical history, morphologic findings of lesions on the CT component, and metabolic activities of PET/CT scan can help reduce false interpretations. Interventional procedures.

  4. Endogenous biotin-binding proteins: an overlooked factor causing false positives in streptavidin-based protein detection

    Science.gov (United States)

    Tytgat, Hanne L P; Schoofs, Geert; Driesen, Michèle; Proost, Paul; Van Damme, Els J M; Vanderleyden, Jos; Lebeer, Sarah

    2015-01-01

    Biotinylation is widely used in DNA, RNA and protein probing assays as this molecule has generally no impact on the biological activity of its substrate. During the streptavidin-based detection of glycoproteins in Lactobacillus rhamnosus GG with biotinylated lectin probes, a strong positive band of approximately 125 kDa was observed, present in different cellular fractions. This potential glycoprotein reacted heavily with concanavalin A (ConA), a lectin that specifically binds glucose and mannose residues. Surprisingly, this protein of 125 kDa could not be purified using a ConA affinity column. Edman degradation of the protein, isolated via cation and anion exchange chromatography, lead to the identification of the band as pyruvate carboxylase, an enzyme of 125 kDa that binds biotin as a cofactor. Detection using only the streptavidin conjugate resulted in more false positive signals of proteins, also in extracellular fractions, indicating biotin-associated proteins. Indeed, biotin is a known cofactor of numerous carboxylases. The potential occurence of false positive bands with biotinylated protein probes should thus be considered when using streptavidin-based detection, e.g. by developing a blot using only the streptavidin conjugate. To circumvent these false positives, alternative approaches like detection based on digoxigenin labelling can also be used. PMID:25211245

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

    Science.gov (United States)

    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.

  6. Usefulness of exercise ECG test with nitroglycerin and exercise cardiac scintigraphy in patients with false positive exercise ECG test

    International Nuclear Information System (INIS)

    Moritani, Kohshiro

    1984-01-01

    The purpose of this study is to evaluate the clinical usefulness of exercise (Ex) ECG test with sublingual nitroglycerin (NTG) and Ex cardiac scintigraphy in differentiating false positive responses from true positive responses of Ex ECG test. We examined 7 pts (age : 46+-7 years) with true positive Ex ECG test (TP) and 8 pts (age : 55+-10 years) with false positive Ex ECG test (FP). TP had significant coronary artery disease and FP did not. Ex test was done by multistage ergometer test. In 5 pts of TP and all pts of FP, Ex cardiac scintigraphy was performed. In TP, Ex cardiac scintigraphy revealed reversible perfusion deficit, but not in FP. NTG was administered 3 minutes before Ex test was started. Ex test with NTG was terminated at the same load as Ex test without NTG. Pressure-rate products at the end point of Ex test did not show significant difference between Ex test without NTG and that with NTG (TP: 203x10 2 , 213x10 2 , FP: 196x10 2 , 206x10 2 , respectively). In 7 pts of FP, ST depression in Ex test without NTG was not improved in Ex test with NTG. On the other hand, in all pts of TP, ST depression seen in Ex test without NTG, was not observed in Ex test with NTG. It may be concluded that Ex cardiac scintigraphy is diagnostic for differentiation of false positive responses from true positive responses of Ex ECG test, as well as Ex ECG test with NTG is. (author)

  7. Blood Culture Contamination and the Type of Microorganisms in True and False Positive Results in Patients Admitted at Avicenna Qazvin

    OpenAIRE

    E Sajadi; S Asefzade; M Asefzade; F Manuchehri

    2010-01-01

    Introduction: Diagnosis of infection based on blood culture alone is not a suitable method, but it is important to understand the clinical diagnosis for interpreting blood cultures. The goal of this study was to determine blood culture contamination and the type of microorganisms in false and real positive cases in patients admitted at Avicenna Hospital. Methods: This cross sectional study was done on all patients in the emergency and internal medicine departments from April, 2008 to October,...

  8. False positives observed on the Seratec® PSA SemiQuant Cassette Test with condom lubricants.

    Science.gov (United States)

    Bitner, Sara E

    2012-11-01

    In the course of the validation of a new component of the prostate-specific antigen (PSA) SemiQuant Cassette Test marketed by Seratec(®) , a false-positive reaction was observed when testing samples collected from the surface of unused, lubricated condoms. A variety of personal lubricants and condoms were tested to determine the frequency of the false positive, as well as its potential source. Samples were extracted in both water and the manufacturer-provided buffer, and the test was performed according to the manufacturer's suggested protocol. The false positive was observed intermittently, but occurred consistently with samples containing nonoxynol-9, a strong detergent utilized as a spermicide. The reaction may be attributable to the combination of latex and nonoxynol-9. Because of the unreliability of the test to confirm the presence of PSA in samples collected from condoms, the PSA cassette is an unsuitable method for confirming the presence of seminal fluid in condoms. 2012 American Academy of Forensic Sciences. Published 2012. This article is a U.S. Government work and is in the public domain in the U.S.A.

  9. Egernia stokesii (gidgee skink) MHC I positively selected sites lack concordance with HLA peptide binding regions.

    Science.gov (United States)

    Pearson, Sarah K; Bull, C Michael; Gardner, Michael G

    2017-01-01

    Genes of the major histocompatibility complex (MHC) play an important role in vertebrate disease resistance, kin recognition and mate choice. Mammalian MHC is the most widely characterised of all vertebrates, and attention is often given to the peptide binding regions of the MHC because they are presumed to be under stronger selection than non-peptide binding regions. For vertebrates where the MHC is less well understood, researchers commonly use the amino acid positions of the peptide binding regions of the human leukocyte antigen (HLA) to infer the peptide binding regions within the MHC sequences of their taxon of interest. However, positively selected sites within MHC have been reported to lack correspondence with the HLA in fish, frogs, birds and reptiles including squamates. Despite squamate diversity, the MHC has been characterised in few snakes and lizards. The Egernia group of scincid lizards is appropriate for investigating mechanisms generating MHC variation, as their inclusion will add a new lineage (i.e. Scincidae) to studies of selection on the MHC. We aimed to identify positively selected sites within the MHC of Egernia stokesii and then determine if these sites corresponded with the peptide binding regions of the HLA. Six positively selected sites were identified within E. stokesii MHC I, only two were homologous with the HLA. E. stokesii positively selected sites corresponded more closely to non-lizard than other lizard taxa. The characterisation of the MHC of more intermediate taxa within the squamate order is necessary to understand the evolution of the MHC across all vertebrates.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  12. Occurrence of false positive results for the detection of carbapenemases in carbapenemase-negative Escherichia coli and Klebsiella pneumoniae isolates.

    Directory of Open Access Journals (Sweden)

    Peng Wang

    Full Text Available Adequate detection of the production of carbapenemase in Enterobacteriaceae isolates is crucial for infection control measures and the appropriate choice of antimicrobial therapy. In this study, we investigated the frequency of false positive results for the detection of carbapenemases in carbapenemase-negative Escherichia coli and Klebsiella pneumoniae clinical isolates by the modified Hodge test (MHT. Three hundred and one E. coli and K. pneumoniae clinical isolates were investigated. All produced extended spectrum β-lactamases (ESBLs but were susceptible to carbapenems. Antimicrobial susceptibility testing was performed by the disk diffusion and agar dilution methods. The MHT was performed using the standard inoculum of test organisms recommended by the CLSI. Genes that encoded ESBLs and carbapenemases were identified by PCR and DNA sequencing. Among the 301 clinical isolates, none of the isolates conformed to the criteria for carbapenemase screening recommended by the CLSI. The susceptibility rates for imipenem, meropenem, and ertapenem all were 100.0%, 100.0%, and 100.0%, respectively. Of the 301 E. coli and K. pneumoniae isolates, none produced carbapenemase. The MHT gave a positive result for 3.3% (10/301 of the isolates. False positive results can occur when the MHT is used to detect carbapenemase in ESBL-producing isolates and clinical laboratories must be aware of this fact.

  13. Recurrent/metastatic thyroid carcinomas false negative for serum thyroglobulin but positive by posttherapy I-131 whole body scans

    International Nuclear Information System (INIS)

    Park, Eun-Kyung; Lee, Dong Soo; Lee, Myung Chul; Chung, June-Key; Lim, Il Han; Park, Do Joon; Cho, Bo Youn

    2009-01-01

    Serum Tg and I-131 WBS have been used to detect recurrent and metastatic thyroid cancers postoperatively. Tg is known to be more sensitive than I-131 WBS, and therefore, false-negative WBS cases with elevated Tg levels are frequently found. However, the clinical characteristics of false-negative Tg cases with positive WBS have not been clarified. The authors evaluated 824 postoperative patients with differentiated thyroid carcinoma who underwent post-ablation/therapy I-131 WBS. Tg negativity was defined as a Tg level of ≤2 ng/mL without TgAb under thyroid-stimulating hormone stimulation. Remission, recurrence, and metastasis were confirmed using pathologic or clinically findings. Fifty-two patients (6.3%) with functioning metastasis and negativity for TgAb were Tg-negative and posttherapy I-131 WBS-positive (TgN group), and 128 patients with functioning metastases were Tg positive and WBS positive (TgP group). The TgN group consisted of 45 cases of cervical/mediastinal lymph node metastases (86.5%) and seven cases of distant metastasis to lung or bone by follow-up WBS. The TgN group demonstrated significantly higher profiles of regional involvement than the TgP group (P < 0.029). In 47 patients in the TgN group, metastatic uptake disappeared in 33, ameliorated in four, and persisted in ten during follow-up. A significant number of differentiated thyroid cancer patients were Tg-/TgAb-negative despite a positive WBS finding. Cervical and mediastinal lymph nodes were predominant sites of metastasis in the TgN group. WBS should be undertaken routinely as a complementary modality to detect functioning recurrence and metastasis regardless of serum Tg results. (orig.)

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

    Science.gov (United States)

    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.

  15. Systematic hybrid LOH: a new method to reduce false positives and negatives during screening of yeast gene deletion libraries

    DEFF Research Database (Denmark)

    Alvaro, D.; Sunjevaric, I.; Reid, R. J.

    2006-01-01

    We have developed a new method, systematic hybrid loss of heterozygosity, to facilitate genomic screens utilizing the yeast gene deletion library. Screening is performed using hybrid diploid strains produced through mating the library haploids with strains from a different genetic background...... complementation of any spurious recessive mutations in the library strain, facilitating attribution of the observed phenotype to the documented gene deletion and dramatically reducing false positive results commonly obtained in library screens. The systematic hybrid LOH method can be applied to virtually any...

  16. Facing the block and false positives in Mohs surgery: a retrospective study of 2,198 cases.

    Science.gov (United States)

    Taylor, Brent R; Groover, Jamie A; Cook, Joel

    2013-11-01

    "Facing the block" is defined as trimming tissue on a microtome from peripheral or deep surgical margins before sectioning. Facing includes trimming performed intentionally but unnecessarily, accidentally, or out of necessity because of one's choice of embedding and freezing method. To assess whether facing the block is associated with a greater number of stages to clear tumor and, by inference, a significant false positive rate. A retrospective analysis was performed comparing the average number of stages per Mohs case at two surgical facilities with the same physician over a 1-year period. Site A histotechnologists intentionally face the block, whereas site B histotechnologists do not. Tissue thickness lost during trimming at each site was recorded for 4 weeks. Comparing Sites A and B, stages per case were 1.92 and 1.53, respectively (p < .01) and trimming depths before the first section were 325 and 187 μm (p < .01). Facing the block is associated with 0.39 more stages per case and, by inference, a false-positive rate of approximately 39%. Mohs surgeons should evaluate the methods of tissue preparation that their histotechnologists use. Facing the block should not be performed. © 2013 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

  17. False-positive axillary lymph node on F-18 FDG PET/CT due to moxibustion therapy

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Shin Young; Lee, Sang Woo; Ahn, Byeong Cheol; Lee, Jae Tae [Kyungpook National University Hospital, Daegu (Korea, Republic of); Seo, Ji Hyoung [Inje University Haeundae Paik Hospital, Busan (Korea, Republic of)

    2010-12-15

    A 30-year-old female was diagnosed with papillary thyroid cancer and underwent total thyroidectomy and high-dose radioiodine ablation. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for recurrence detection of thyroid carcinoma was performed at 3 years after total thyroidectomy. Moxibustion is a traditional Chinese medicine therapy using moxa or the mugwort herb. Moxibustion is the burning of a small, thimble-sized, smoldering plug of dried leaves such as moxa or mugwort on the skin at an acupuncture point. Acupuncture and moxibustion induce hyperemia and a local inflammatory reaction. Complications associated with moxibustion such as skin bums or infection of the site have been reported previously. False-positive FDG uptake in PET may result from inflammation, infection, and variations in physiological uptake. In the present case, the hypermetabolic axillary lymph node disappeared without any treatment. Well-known of false-positive FDG uptake in axillary lymph noes such as arthritis of the upper extremity, extravasation of injected FDG, and vaccination were not found. Thus, left axillary lymph node uptake was

  18. False-positive axillary lymph node on F-18 FDG PET/CT due to moxibustion therapy

    International Nuclear Information System (INIS)

    Jeong, Shin Young; Lee, Sang Woo; Ahn, Byeong Cheol; Lee, Jae Tae; Seo, Ji Hyoung

    2010-01-01

    A 30-year-old female was diagnosed with papillary thyroid cancer and underwent total thyroidectomy and high-dose radioiodine ablation. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for recurrence detection of thyroid carcinoma was performed at 3 years after total thyroidectomy. Moxibustion is a traditional Chinese medicine therapy using moxa or the mugwort herb. Moxibustion is the burning of a small, thimble-sized, smoldering plug of dried leaves such as moxa or mugwort on the skin at an acupuncture point. Acupuncture and moxibustion induce hyperemia and a local inflammatory reaction. Complications associated with moxibustion such as skin bums or infection of the site have been reported previously. False-positive FDG uptake in PET may result from inflammation, infection, and variations in physiological uptake. In the present case, the hypermetabolic axillary lymph node disappeared without any treatment. Well-known of false-positive FDG uptake in axillary lymph noes such as arthritis of the upper extremity, extravasation of injected FDG, and vaccination were not found. Thus, left axillary lymph node uptake was

  19. False Positive Findings on I-131 WBS and SPECT/CT in Patients with History of Thyroid Cancer: Case Series

    Directory of Open Access Journals (Sweden)

    Zeina C. Hannoush

    2017-01-01

    Full Text Available Introduction. Although whole body scan (WBS with I-131 is a highly sensitive tool for detecting normal thyroid tissue and metastasis of differentiated thyroid cancer (DTC, it is not specific. Additional information, provided by single photon emission computed tomography combined with X-ray computed tomography (SPECT/CT and by the serum thyroglobulin level, is extremely useful for the interpretation of findings. Case Presentation. We report four cases of false positive WBS in patients with DTC: ovarian uptake corresponding to an endometrioma, scrotal uptake due to a spermatocele, rib-cage uptake due to an old fracture, and hepatic and renal uptake secondary to a granuloma and simple cyst, respectively. Conclusions. Trapping, organification, and storage of iodine are more prominent in thyroid tissue but not specific. Physiologic sodium-iodine symporter expression in other tissues explains some, but not all, of the WBS false positive cases. Other proposed etiologies are accumulation of radioiodine in inflamed organs, metabolism of radiodinated thyroid hormone, presence of radioiodine in body fluids, and contamination. In our cases nonthyroidal pathologies were suspected since the imaging findings were not corroborated by an elevated thyroglobulin level, which is considered a reliable tumor marker for most well-differentiated thyroid cancers. Clinicians should be aware of the potential pitfalls of WBS in DTC to avoid incorrect management.

  20. Impact of intermediate mammography assessment on the likelihood of false-positive results in breast cancer screening programmes

    Energy Technology Data Exchange (ETDEWEB)

    Ascunce, Nieves [Public Health Institute, CIBERESP, Navarra Breast Cancer Screening Programme, Pamplona (Spain); Instituto de Salud Publica, Navarra Breast Cancer Screening Programme, Pamplona (Spain); Ederra, Maria; Delfrade, Josu; Erdozain, Nieves [Public Health Institute, CIBERESP, Navarra Breast Cancer Screening Programme, Pamplona (Spain); Baroja, Araceli [Fundacion Rioja Salud, Logrono (Spain); Zubizarreta, Raquel [Public Health and Planning Directorate, Health Office, Galician Breast Cancer Screening Programme, Galicia (Spain); Salas, Dolores [General Directorate Public Health and Centre for Public Health Research (CSISP), Valencia (Spain); Castells, Xavier [Mar Teaching Hospital, CIBERESP, Department of Clinical Epidemiology, Barcelona (Spain)

    2012-02-15

    Breast cancer screening is offered to 100% of the target population in Spain and intermediate mammograms (IMs) are sometimes indicated. This study was aimed at analysing the frequency of IMs, the factors determining their recommendation, and their impact on the risk of false-positive results and the detection rate. Data from 3,471,307 mammograms from Spanish breast cancer screening programmes were included. 3.36% of the mammograms were IMs. The factors associated with the use of IMs were age, initial screening, previous invasive tests, a familial history of breast cancer and use of hormone replacement therapy. In screening episodes with an IM, the probability of a false-positive result was 13.74% (95% CI: 13.43-14.05), almost double that in episodes without IMs (6.02%, 95% CI 5.99-6.05). In young women with previous invasive procedures, a familial history of breast cancer or hormone replacement therapy use who were undergoing their initial screen, this probability was lower when IMs were performed. IMs always increased the detection rate. The factors prompting IMs should be characterised so that radiologists can systematise their recommendations according to the presence of the factors maximising the benefits and minimising the adverse effects of this procedure. (orig.)

  1. Three-dimensional lung nodule segmentation and shape variance analysis to detect lung cancer with reduced false positives.

    Science.gov (United States)

    Krishnamurthy, Senthilkumar; Narasimhan, Ganesh; Rengasamy, Umamaheswari

    2016-01-01

    The three-dimensional analysis on lung computed tomography scan was carried out in this study to detect the malignant lung nodules. An automatic three-dimensional segmentation algorithm proposed here efficiently segmented the tissue clusters (nodules) inside the lung. However, an automatic morphological region-grow segmentation algorithm that was implemented to segment the well-circumscribed nodules present inside the lung did not segment the juxta-pleural nodule present on the inner surface of wall of the lung. A novel edge bridge and fill technique is proposed in this article to segment the juxta-pleural and pleural-tail nodules accurately. The centroid shift of each candidate nodule was computed. The nodules with more centroid shift in the consecutive slices were eliminated since malignant nodule's resultant position did not usually deviate. The three-dimensional shape variation and edge sharp analyses were performed to reduce the false positives and to classify the malignant nodules. The change in area and equivalent diameter was more for malignant nodules in the consecutive slices and the malignant nodules showed a sharp edge. Segmentation was followed by three-dimensional centroid, shape and edge analysis which was carried out on a lung computed tomography database of 20 patient with 25 malignant nodules. The algorithms proposed in this article precisely detected 22 malignant nodules and failed to detect 3 with a sensitivity of 88%. Furthermore, this algorithm correctly eliminated 216 tissue clusters that were initially segmented as nodules; however, 41 non-malignant tissue clusters were detected as malignant nodules. Therefore, the false positive of this algorithm was 2.05 per patient. © IMechE 2016.

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

    Energy Technology Data Exchange (ETDEWEB)

    Désert, Jean-Michel; Brown, Timothy M. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Charbonneau, David; Torres, Guillermo; Fressin, François; Ballard, Sarah; Latham, David W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bryson, Stephen T.; Borucki, William J. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Knutson, Heather A. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Batalha, Natalie M. [San Jose State University, San Jose, CA 95192 (United States); Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Ford, Eric B. [University of Florida, Gainesville, FL 32611 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Gilliland, Ronald L. [Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, University Park, PA 16802 (United States); Seager, Sara, E-mail: desert@colorado.edu [Massachusetts Institute of Technology, Cambridge, MA 02159 (United States)

    2015-05-01

    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) among 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 investigated

  3. Phase II Study of Personalized Peptide Vaccination with Both a Hepatitis C Virus-Derived Peptide and Peptides from Tumor-Associated Antigens for the Treatment of HCV-Positive Advanced Hepatocellular Carcinoma Patients

    Directory of Open Access Journals (Sweden)

    Shigeru Yutani

    2015-01-01

    Full Text Available Objective. To evaluate safety and immune responses of personalized peptide vaccination (PPV for hepatitis C virus- (HCV- positive advanced hepatocellular carcinoma (HCC. Patients and Methods. Patients diagnosed with HCV-positive advanced HCC were eligible for this study. A maximum of four HLA-matched peptides were selected based on the preexisting IgG responses specific to 32 different peptides, which consisted of a single HCV-derived peptide at core protein positions 35–44 (C-35 and 31 peptides derived from 15 different tumor-associated antigens (TAAs, followed by subcutaneous administration once per week for 8 weeks. Peptide-specific cytotoxic T lymphocyte (CTL and IgG responses were measured before and after vaccination. Results. Forty-two patients were enrolled. Grade 3 injection site skin reaction was observed in 2 patients, but no other PPV-related severe adverse events were noted. Peptide-specific CTL responses before vaccination were observed in only 3 of 42 patients, but they became detectable in 23 of 36 patients tested after vaccination. Peptide-specific IgG responses were also boosted in 19 of 36 patients. Peptide-specific IgG1 responses to both C-35 and TAA-derived peptides could be potentially prognostic for overall survival. Conclusion. Further clinical study of PPV would be warranted for HCV-positive advanced HCC, based on the safety and strong immune induction.

  4. Blank-comparison matching-to-sample reveals a false positive symmetry test in a capuchin monkey.

    Science.gov (United States)

    de Faria Brino, Ana Leda; da Silva Campos, Rodolfo; de Faria Galvão, Olavo; McIlvane, William Jay

    2014-06-01

    A positive symmetry test result was obtained with a capuchin monkey that had previously exhibited virtually errorless AB and BA arbitrary matching-to-sample (MTS) with different stimuli. The symmetry test (BA) followed the acquisition of a new AB relation. It seemed possible, however, that the positive result could have occurred through the exclusion of previously defined comparison stimuli and not because the new AB and BA relations had the property of symmetry. To assess this possibility, a blank-comparison MTS procedure was implemented that permitted the separate assessment of select and reject (i.e., exclusion) control with both baseline and BA matching relations. In this assessment, the monkey did not exhibit reliable BA matching when exclusion was not possible, thus showing that the symmetry result was a false positive. However, the study demonstrated the feasibility of using a blank comparison MTS procedure with capuchins. The present results may set the stage for more successful methodology for establishing desired forms of relational stimulus control in capuchins and ultimately improving the assessment of relational learning capacity in that species, other nonhuman species, and nonverbal humans.

  5. Benign thyroid and neck lesions mimicking malignancy with false positive findings on positron emission tomography-computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Ye Ri; Kim, Shin Young; Lee, Sang Mi [Soonchunhyang University Cheonan Hospital, Cheonan (Korea, Republic of); Lee, Deuk Young [Dept. of Surgery, Younsei Angelot Women' s Clinic, Cheonan (Korea, Republic of)

    2017-02-15

    The increasing use of positron emission tomography-computed tomography (PET/CT) has led to the frequent detection of incidental thyroid and neck lesions with increased 18F-deoxyglucose (FDG) uptake. Although lesions with increased FDG uptake are commonly assumed to be malignant, benign lesions may also exhibit increased uptake. The purpose of this pictorial essay is to demonstrate that benign thyroid and neck lesions can produce false-positive findings on PET/CT, and to identify various difficulties in interpretation. It is crucial to be aware that differentiating between benign and malignant lesions is difficult in a considerable proportion of cases, when relying only on PET/CT findings. Correlation of PET/CT findings with additional imaging modalities is essential to avoid misdiagnosis.

  6. Screening for colorectal neoplasias with fecal occult blood tests: false-positive impact of non-dietary restriction.

    Science.gov (United States)

    Roslani, April Camilla; Abdullah, Taufiq; Arumugam, Kulenthran

    2012-01-01

    Screening for colorectal cancer using guaiac-based fecal occult blood tests (gFOBT) is well established in Western populations, but is hampered by poor patient compliance due to the imposed dietary restrictions. Fecal immunochemical tests (FIT) do not require dietary restriction, but are more expensive than gFOBT and therefore restrict its use in developing countries in Asia. However, Asian diets being low in meat content may not require diet restriction for gFOBT to achieve equivalent results. The objective of this study was to evaluate and compare the validity and suitability of gFOBT and FIT or a combination of the two in screening for colorectal neoplasias without prior dietary restriction in an Asian population. Patients referred to the Endoscopic Unit for colonoscopy were recruited for the study. Stool samples were collected prior to bowel preparation, and tested for occult blood with both gFOBT and FIT. Dietary restriction was not imposed. To assess the validity of either tests or in combination to detect a neoplasm or cancer in the colon, their false positive rates, their sensitivity (true positive rate) and the specificity (true negative rate) were analyzed and compared. One hundred and three patients were analysed. The sensitivity for picking up any neoplasia was 53% for FIT, 40% for gFOBT and 23.3% for the combination. The sensitivities for picking up only carcinoma were 77.8% , 66.7% and 55.5%, respectively. The specificity for excluding any neoplasia was 91.7% for FIT, 74% for gFOBT and 94.5% for a combination, whereas for excluding only carcinomas they were 84%, 73.4% and 93.6%. Of the 69 with normal colonoscopic findings, FOBT was positive in 4.3%, 23.2 %and 2.9% for FIT, gFOBT, or combination of tests respectively. FIT is the recommended method if we are to dispense with dietary restriction in our patients because of its relatively low-false positivity and better sensitivity and specificity rates.

  7. Fluorescent particles in the antibody solution result in false TF- and CD14-positive microparticles in flow cytometric analysis.

    Science.gov (United States)

    Aass, Hans Christian D; Øvstebø, Reidun; Trøseid, Anne-Marie S; Kierulf, Peter; Berg, Jens Petter; Henriksson, Carola Elisabeth

    2011-12-01

    Tissue factor (TF)-positive microparticles (MPs) are highly procoagulant, and linked to thrombosis in sepsis and cancer. MP-associated TF may be assayed by immunological or functional methods. Several reports have demonstrated discrepancies between TF-protein and TF-activity, which have been explained by antibody binding to "encrypted" or degraded forms of inactive TF-protein. Our goal was to evaluate the possible interference of fluorescent antibody aggregates in solutions containing antibodies against TF and CD14 in flow cytometric analysis. Using monocyte-derived microparticles (MPs) released from human monocytes, incubated with or without lipopolysaccharides (LPS) in vitro, we measured MP-associated TF-protein (flow cytometry) and TF-activity (clot formation assay). MPs released from monocytes exposed to LPS (1 ng mL(-1) ) had ∼14 times higher TF-activity than MPs originated from monocytes exposed to only culture medium. However, using untreated anti-TF antibodies (American Diagnostica and BD) in the flow cytometric analysis, MPs released from unstimulated monocytes had a similar number of TF-positive events as MPs secernated from LPS-stimulated monocytes [∼45,000 events mL(-1) (American Diagnostica); ∼15,000 events mL(-1) (BD)]. These TF-positive events did not exert any TF-activity, and centrifugation (17,000g, 30 min, 4°C) of the antibody solutions prior to use effectively removed the interfering fluorescent events. Removal of fluorescent interference, probably in the form of fluorescent antibody aggregates, from the antibody solutions by centrifugation is essential to prevent the occurrence of false positive flow cytometric events. The events can be mistaken as MP-associated TF-protein, and interpreted as a discrepancy between TF-protein and TF-activity. Copyright © 2011 International Society for Advancement of Cytometry.

  8. A systematic review of the psychological impact of false-positive colorectal cancer screening: What is the role of the general practitioner?

    Science.gov (United States)

    van der Velde, J L; Blanker, M H; Stegmann, M E; de Bock, G H; Berger, M Y; Berendsen, A J

    2017-05-01

    Screening for colorectal cancer (CRC) has both advantages (e.g. reduction in morbidity and mortality) and disadvantages (e.g. false positives and distress). A systematic review was therefore performed to improve our understanding of how false-positive CRC screening results affect patients psychologically (and to make recommendations for primary care). The PubMed, Embase, PsychINFO, CINAHL and Cochrane databases were searched in October 2014 and supplemented in December 2016 to identify studies on the psychological impact of false-positive CRC screening. Original studies were eligible when they assessed psychological impact in a screening setting, provided they also included false-positive CRC screening results. Two authors independently assessed 2,367 available manuscripts and included seven. Heterogeneity in their outcome measures meant that data could not be pooled. Two studies showed that a false-positive CRC screening result caused some moderate psychological distress shortly before and after colonoscopy. The remaining five studies illustrated that the psychological distress of patients with true-positive and false-positive CRC screening results was comparable. We conclude that a false-positive CRC screening result may cause some moderate psychological distress, especially just before or after colonoscopy. We recommend that general practitioners mention this when discussing CRC screening with patients and monitor those with a false-positive outcome for psychological distress. © 2017 John Wiley & Sons Ltd.

  9. A systematic review of the psychological impact of false-positive colorectal cancer screening : What is the role of the general practitioner?

    NARCIS (Netherlands)

    van der Velde, J. L.; Blanker, M. H.; Stegmann, M. E.; de Bock, G. H.; Berger, M. Y.; Berendsen, A. J.

    Screening for colorectal cancer (CRC) has both advantages (e.g. reduction in morbidity and mortality) and disadvantages (e.g. false positives and distress). A systematic review was therefore performed to improve our understanding of how false-positive CRC screening results affect patients

  10. Computer-aided mass detection in mammography: False positive reduction via gray-scale invariant ranklet texture features

    International Nuclear Information System (INIS)

    Masotti, Matteo; Lanconelli, Nico; Campanini, Renato

    2009-01-01

    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 their 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 marks

  11. Peptide insertion, positioning, and stabilization in a membrane: insight from an all-atom molecular dynamics simulation.

    Science.gov (United States)

    Babakhani, Arneh; Gorfe, Alemayehu A; Gullingsrud, Justin; Kim, Judy E; Andrew McCammon, J

    Peptide insertion, positioning, and stabilization in a model membrane are probed via an all-atom molecular dynamics (MD) simulation. One peptide (WL5) is simulated in each leaflet of a solvated dimyristoylglycero-3-phosphate (DMPC) membrane. Within the first 5 ns, the peptides spontaneously insert into the membrane and then stabilize during the remaining 70 ns of simulation time. In both leaflets, the peptides localize to the membrane interface, and this localization is attributed to the formation of peptide-lipid hydrogen bonds. We show that the single tryptophan residue in each peptide contributes significantly to these hydrogen bonds; specifically, the nitrogen heteroatom of the indole ring plays a critical role. The tilt angles of the indole rings relative to the membrane normal in the upper and lower leaflets are approximately 26 degrees and 54 degrees , respectively. The tilt angles of the entire peptide chain are 62 degrees and 74 degrees . The membrane induces conformations of the peptide that are characteristic of beta-sheets, and the peptide enhances the lipid ordering in the membrane. Finally, the diffusion rate of the peptides in the membrane plane is calculated (based on experimental peptide concentrations) to be approximately 6 A(2)/ns, thus suggesting a 500 ns time scale for intermolecular interactions.

  12. Polymer nanoassemblies with hydrophobic pendant groups in the core induce false positive siRNA transfection in luciferase reporter assays.

    Science.gov (United States)

    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'transfection in the luciferase assay. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Simplified false-positive reduction in computer-aided detection scheme of clustered microcalcifications in digital breast tomosynthesis

    Science.gov (United States)

    Jeong, Ji-Wook; Chae, Seung-Hoon; Lee, Sooyeul; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook

    2015-03-01

    A computer-aided detection (CADe) system for clustered microcalcifications (MCs) in reconstructed digital breast tomosynthesis (DBT) volumes was suggested. The system consisted of prescreening, MC detecting, clustering, and falsepositive reduction steps. In the prescreening stage, the MC-like objects were enhanced by a multiscale-based 3D calcification response function. A connected component segmentation method was used to detect cluster seed objects, which were considered as potential clustering centers of MCs. Starting with each cluster seed object as the initial cluster center, a cluster candidate was formed by including nearby MC candidates within a 3D neighborhood of the cluster seed object satisfying the clustering criteria during the clustering step. The size and number of the clustered MCs in a cluster seed candidate were used to reduce the number of FPs. A bounding cube for each MCC was generated for each accepted seed candidates. Then, the overlapping cubes were combined and examined according to the FP reduction criteria. After FP reduction step, we obtained the average number of FPs of 2.47 per DBT volume with sensitivity of 83.3%. Our study indicates the simplified false-positive reduction approach applied to the detection of clustered MCs in DBT is promising as an efficient CADe system.

  14. 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

    Energy Technology Data Exchange (ETDEWEB)

    Boehnke, E McKenzie; DeMarco, J; Steers, J; Fraass, B [Cedars-Sinai Medical Center, Los Angeles, CA (United States)

    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 readings 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 Foundation.

  15. Survey of False-positive Reactivity of Latex Agglutination Test for Kala-azar (Katex) without Urine Sample Boiling Process in Autoimmune Patients.

    Science.gov (United States)

    Ghatee, Mohammad Amin; Kanannejad, Zahra; Sharifi, Iraj; Askari, Asma; Bamorovat, Mehdi

    2017-06-01

    Latex agglutination test for Kala-azar (KAtex) is an easy, inexpensive, and field-applicable antigen detection test. However, the main drawback of this method is the boiling step applied to remove false positivity of the test. This study was conducted to survey false positivity results of latex agglutination test for KAtex without boiling process in urine of some autoimmune patients. Ninety-two urine samples from autoimmune patients including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), scleroderma, autoimmune vasculitis, vitiligo, pemphigus and Wagner cases and 20 urine samples from healthy individuals were collected from Kerman Province in Southeastern Iran in 2010-2011. All urine samples were checked by KAtex after boiling for 5 min false positivity rate of the test was surveyed in different healthy and patients groups while boiling process was removed. Rheumatoid factor (RF) then was checked in sera of all cases to evaluate the relationship between RF and KAtex false positivity. All samples represented negative results with KAtex when boiling was performed (100% specificity). Then, 20% positivity was evident in healthy cases. False-positive reactivity was more prominent observed in patient groups than healthy individuals, except in vitiligo. However, a significant difference was only observed in RA group ( P boiling process removal.

  16. Retroperitoneal Endometriosis: A Possible Cause of False Positive Finding at 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

    International Nuclear Information System (INIS)

    Maffione, Anna Margherita; Panzavolta, Riccardo; Lisato, Laura Camilla; Ballotta, Maria; D'Isanto, Mariangela Zanforlini; Rubello, Domenico

    2015-01-01

    Endometriosis is a frequent and clinically relevant problem in young women. Laparoscopy is still the gold standard for the diagnosis of endometriosis, but frequently both morphologic and functional imaging techniques are involved in the diagnostic course before achieving a conclusive diagnosis. We present a case of a patient affected by infiltrating retroperitoneal endometriosis falsely interpreted as a malignant mass by contrast-enhanced magnetic resonance imaging and 18 F-fluorodeoxyglucose positron emission tomography/computed tomography

  17. Positive Correlation of PTH-Related Peptide with Glucose in Type 2 Diabetes

    Directory of Open Access Journals (Sweden)

    Ioannis Legakis

    2009-01-01

    Full Text Available Type 2 diabetes is characterized by hyperglycemia resulting from insulin resistance in the setting of inadequate beta-cell compensation. Recent studies indicate that for attaining a well-functioning ß-cell mass, parathyroid hormone-related protein (PTHrP is a very promising candidate among several insulinotropic peptides. In order to elucidate its role, we determine the levels of PTHrP, insulin and c-peptide in type 2 diabetics and in normal subjects in the fasting state. We enrolled 28 patients (16 men and 12 postmenopausal women with type 2 diabetes and twenty eight aged-matched healthy individuals as control subjects (15 men and 13 women. PTHrP was statistically significant correlated with glucose in type 2 diabetes and in normal subjects in the fasting state. Additionally, PTHrP serum levels exhibited a significant increase in type 2 diabetes compared to control subjects. Interestingly, PTHrP showed a positive correlation with insulin levels only among healthy individuals presumably due to defective glucose stimulated insulin secretion known to occur in type 2 diabetics. In conclusion ,the strong positive relation of PTHrP with glucose in the fasting state in patients with type 2 diabetes mellitus raises several questions for further experimentation concerning its exact role and physiological significance.

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

    Science.gov (United States)

    Grégoire, Y; Germain, M; Delage, G

    2018-03-06

    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 entry, rates of deferral for second false-positive results were 8·4% after 3 years [different platform: 1·8%; same platform: 21·4% (P 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.

  19. Small Intestinal Bacterial Overgrowth May Increase the Likelihood of Lactose and Sorbitol but not Fructose Intolerance False Positive Diagnosis.

    Science.gov (United States)

    Perets, Tsachi Tsadok; Hamouda, Dalal; Layfer, Olga; Ashorov, Olga; Boltin, Doron; Levy, Sigal; Niv, Yaron; Dickman, Ram

    2017-08-01

    Small intestinal bacterial overgrowth (SIBO) is defined as a bacterial count of more than 10 5 colony-forming units per milliliter in duodenal aspirate. It shares many symptoms with carbohydrate intolerance, which makes the clinical distinction of the disorders difficult. The aim of the study was to examine the relationship between a positive carbohydrate breath test and the presence of SIBO suggested by a positive lactulose hydrogen breath test. The electronic database of the gastroenterology laboratory of a tertiary medical center was searched for all patients clinically tested for SIBO in 2012-2013 for whom previous results for lactose, fructose, and/or sorbitol breath test were available. The correlation between positive findings for carbohydrate intolerance and for SIBO was statistically analyzed. The study group included 349 patients, 231 female and 118 male, of mean age 53±19 years. All had symptoms of abdominal bloating and gas. There was a statistically significant difference in rates of a positive breath test for lactose and sorbitol at ≤90 minutes between patients who were positive and negative for SIBO [χ 2 (1)=12.8, p intolerance. It may be especially prudent to exclude SIBO patients with an early peak (≤90 minutes) in H 2 excretion. © 2017 by the Association of Clinical Scientists, Inc.

  20. Effect of positively charged short peptides on stability of cubic phases of monoolein/dioleoylphosphatidic acid mixtures.

    Science.gov (United States)

    Masum, Shah Md; Li, Shu Jie; Awad, Tarek S; Yamazaki, Masahito

    2005-06-07

    To elucidate the stability and phase transition of cubic phases of biomembranes with infinite periodic minimal surface is indispensable from biological and physicochemical aspects. In this report, we investigated the effect of positively charged peptide-3K (LLKKK) and poly(L-lysine) on the phase stability of monoolein (MO) membranes containing negatively charged dioleoylphosphatidic acid (DOPA) (i.e., DOPA/MO membranes) using small-angle X-ray scattering. At first, the effect of peptide-3K on 10% DOPA/90% MO membrane in excess water, which is in the Q229 phase, was investigated. At 3.4 mM peptide-3K, a Q229 to Q230 phase transition occurred, and at >3.4 mM peptide-3K, the membrane was in the Q230 phase. Poly(L-lysine) (M(w) 1K-4K) also induced the Q230 phase, but peptide-2K (LLKK) could not induce it in the same membrane. We also investigated the effect of peptide-3K on the multilamellar vesicle (MLV) of 25% DOPA/75% MO membrane, which is in L(alpha) phase. In the absence of peptide, the spacing of MLV was very large (11.3 nm), but at > or = 8 mM peptide-3K, it greatly decreased to a constant value (5.2 nm), irrespective of the peptide concentration, indicating that peptide-3K and the membranes form an electrostatically stabilized aggregation with low water content. Poly(L-lysine) also decreased greatly the spacing of the 25% DOPA/75% MO MLV, indicating the formation of a similar aggregation. To compare the effects of peptide-3K and poly(L-lysine) with that of osmotic stress on stability of the cubic phase, we investigated the effect of poly(ethylene glycol) with molecular weight 7500 (PEG-6K) on the phase stability of 10% DOPA/90% MO membrane. With an increase in PEG-6K concentration, i.e., with an increase in osmotic stress, the most stable phase changed as follows; Q229 (Schwartz's P surface) --> Q224 (D) --> Q230 (G). On the basis of these results, we discuss the mechanism of the effects of the positively charged short peptides (peptide-3K) and poly

  1. Recall Latencies, Confidence, and Output Positions of True and False Memories: Implications for Recall and Metamemory Theories

    Science.gov (United States)

    Jou, Jerwen

    2008-01-01

    Recall latency, recall accuracy rate, and recall confidence were examined in free recall as a function of recall output serial position using a modified Deese-Roediger-McDermott paradigm to test a strength-based theory against the dual-retrieval process theory of recall output sequence. The strength theory predicts the item output sequence to be…

  2. False teeth

    African Journals Online (AJOL)

    FOMCS2

    diseases (false teeth and millet disease), and history of oc- currence of false teeth or millet disease in a household and on type of health care offered to the patients of false teeth or millet disease. Data management and analysis. The data collected was edited, coded and cleaned before analysis. Statistical packages Epi info ...

  3. Radiodine administration under suppression of TSH for identification of false positive receptions in patients with thyroid differentiated carcinoma (TDC): utility of the potassium perchlorate

    International Nuclear Information System (INIS)

    Santangelo, L.A.; Pitoia, F.; Sanz, C.; Niepomniszcze, H.; El Tamer, Elias

    2004-01-01

    The total body scan, after a dose of 131 I correlated with the measurement of stimulated Tg, constitute the principal pillars in follow-up of patients with TDC (thyroid differentiated carcinoma). A bibliographical search revealed more than 70 situations that can cause false total body scans positive. The examination is essential to avoid unnecessary treatment with radioiodine. The object is to evaluate the effectiveness of the radioiodine administration under hormonal therapy thyroid suppressive (THST) to eliminate the possibility of a false total body scan positive in five patients with TDC with stimulated Tg <1ng/ml

  4. False data, positive results in neurobiology: moving beyond the epigenetics of blood and saliva samples in mental disorders.

    Science.gov (United States)

    Cariaga-Martinez, A; Alelú-Paz, R

    2016-12-12

    Many psychiatric diseases are influenced by a set of several genetic and environmental factors that genetics alone cannot explain. Specifically, in schizophrenia and bipolar disorder the absence of consistently replicated genetic effects together with evidence for lasting changes in gene expression after environmental exposures suggest a role of epigenetic mechanisms in its pathophysiological mechanisms. In this field, the presence of positive results could potentially uncover molecular mechanisms of deregulated gene expression in these complex disorders. In this commentary we have reviewed the positive data obtained over the last 5 years from the scientific literature published in PubMed and we have shown that these results are based on peripheral samples (blood, saliva and other fluids) that do not allow us to obtain reliable and/or valid results, under any circumstances. Finally, we highlight the need to employ human brain samples in the epigenetic study of mental disorders.

  5. Endogenous biotin-binding proteins: an overlooked factor causing false positives in streptavidin-based protein detection

    OpenAIRE

    Tytgat, Hanne L P; Schoofs, Geert; Driesen, Mich?le; Proost, Paul; Van Damme, Els J M; Vanderleyden, Jos; Lebeer, Sarah

    2014-01-01

    Abstract: Biotinylation is widely used in DNA, RNA and protein probing assays as this molecule has generally no impact on the biological activity of its substrate. During the streptavidin-based detection of glycoproteins in Lactobacillus rhamnosus GG with biotinylated lectin probes, a strong positive band of approximately 125 kDa was observed, present in different cellular fractions. This potential glycoprotein reacted heavily with concanavalin A (ConA), a lectin that specifically binds...

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

    DEFF Research Database (Denmark)

    Reveko, Valeriia; Lampert, Felix; Din, Rameez Ud

    2018-01-01

    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...... 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. Results The DPC spot test indicated the presence of hexavalent chromium in aged, but not new, trivalent...

  7. Problems of false positive laboratory tests during qualification to the ”Program of severe plaque psoriasis treatment” on the basis of two cases

    Directory of Open Access Journals (Sweden)

    Dorota Jaśkiewicz-Nyckowska

    2015-03-01

    Full Text Available Introduction. Qualification of patients for the therapeutic program of severe plaque psoriasis should be preceded by many tests. Abnormal test results require further evaluation and possibly implementation of treatment. False positive results lead to prolongation of the qualification process and may cause disqualification of the patient. Objective. To draw attention to qualification to a drug program. Case reports . A screening test for Lyme disease performed in a 45-year-old man, during qualification for biological treatment, was positive, but verification by Western blot showed a negative result. It caused significant prolongation of the qualification process. In a 26-year-old patient the QuantiFERON test gave a positive result. It was repeated in another laboratory and a negative result was established. Conclusions . False-positive results may result in disqualification from biological treatment. Exchange of experience between doctors is essential for improving inclusion criteria of patients for biological therapy.

  8. Risk stratification of women with false-positive test results in mammography screening based on mammographic morphology and density

    DEFF Research Database (Denmark)

    Winkel, Rikke Rass; von Euler-Chelpin, My Catarina; Lynge, Elsebeth

    2017-01-01

    the Breast Imaging-Reporting and Data System (BI-RADS) density classification, the Tabár classification, and two automated techniques quantifying percentage mammographic density (PMD) and mammographic texture (MTR), respectively. The association with breast cancer was estimated using binary logistic...... regression calculating Odds Ratios (ORs) and the area under the receiver operating characteristic (ROC) curves (AUCs) adjusted for birth year and age and invitation round at the FP-screen Results: Significantly increased ORs were seen for BI-RADS D(density)2-D4 (OR 1.94; 1.30-2.91, 2.36; 1.51-3.70 and 4...... Abbreviations: ACRthe American College of RadiologyAUCarea under the ROC curveBI-RADSBreast Imaging Reporting and Data SystemCCcraniocaudalDCISductal carcinoma in situFPfalse-positiveHRThormone replacement treatmentMLOmediolateral obliqueMTRmammographic texture resemblancePMDPercentage Mammographic Density...

  9. Proportion of false-positive lesions at interim and end-of-treatment FDG-PET in lymphoma as determined by histology : Systematic review and meta-analysis

    NARCIS (Netherlands)

    Adams, Hugo J A; Kwee, Thomas C.

    2016-01-01

    Purpose To systematically review and meta-analyze the proportion of false-positive lesions at interim and end-of-treatment 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in lymphoma using biopsy as reference standard. Materials and methods Medline was searched for original

  10. False-positive rate of positron emission tomography/computed tomography for presumed solitary metastatic adrenal disease in patients with known malignancy.

    Science.gov (United States)

    Kuritzkes, Benjamin; Parikh, Manish; Melamed, Jonathan; Hindman, Nicole; Pachter, H L

    2015-02-01

    The aim of this study was to determine the diagnostic accuracy of positron emission tomography (PET) in cancer patients undergoing adrenalectomy for presumed metastatic disease, utilizing the gold standard of histopathology. We retrospectively reviewed all adrenalectomies for metastatic disease performed at our institution over the last 12 years. Preoperative PET scans were compared with final pathology reports. Statistical analyses were performed with Fisher's exact test for categorical variables and Student's t test for continuous variables. Forty-nine adrenalectomies were performed for metastatic disease. Thirty had preoperative PET imaging and were included in this analysis. Mean age was 65.5 ± 13.6 years (29-91) and 54 % were male. Mean size was 3.8 cm (0.4-7.1). Primary tumor distribution was 61 % (n = 17) pulmonary; 11 % (n = 3) breast; 7 % (n = 2) gastric; 7 % (n = 2) renal; and 4 % (n = 1) each of brain, lymphoma, melanoma, and uterine. Mean standardized uptake value (SUV) was 11 ± 7.3 (3.2-30.0). Final pathology revealed that 80 % (25/30) were positive for metastatic disease and 20 % (5/30) were negative. The positive predictive value of PET in correctly identifying adrenal metastatic disease was 83 % (24 true-positive cases and 5 false-positive cases); there was one false-negative PET. False-positive PET results were not correlated with sex (p = 0.35), age (p = 0.24), or maximum SUV units (p = 0.26). The 20 % false-positive rate for PET-positive adrenalectomies performed for metastatic disease should warrant its inclusion in preoperative counseling to the patient and interaction with the treating oncologist.

  11. Screening outcomes in older US women undergoing multiple mammograms in community practice: does interval, age, or comorbidity score affect tumor characteristics or false positive rates?

    Science.gov (United States)

    Braithwaite, Dejana; Zhu, Weiwei; Hubbard, Rebecca A; O'Meara, Ellen S; Miglioretti, Diana L; Geller, Berta; Dittus, Kim; Moore, Dan; Wernli, Karen J; Mandelblatt, Jeanne; Kerlikowske, Karla

    2013-03-06

    Background Uncertainty exists about the appropriate use of screening mammography among older women because comorbid illnesses may diminish the benefit of screening. We examined the risk of adverse tumor characteristics and false positive rates according to screening interval, age, and comorbidity. Methods From January 1999 to December 2006, data were collected prospectively on 2993 older women with breast cancer and 137 949 older women without breast cancer who underwent mammography at facilities that participated in a data linkage between the Breast Cancer Surveillance Consortium and Medicare claims. Women were aged 66 to 89 years at study entry to allow for measurement of 1 year of preexisting illnesses. We used logistic regression analyses to calculate the odds of advanced (IIb, III, IV) stage, large (>20 millimeters) tumors, and 10-year cumulative probability of false-positive mammography by screening frequency (1 vs 2 years), age, and comorbidity score. The comorbidity score was derived using the Klabunde approximation of the Charlson score. All statistical tests were two-sided. Results Adverse tumor characteristics did not differ statistically significantly by comorbidity, age, or interval. Cumulative probability of a false-positive mammography result was higher among annual screeners than biennial screeners irrespective of comorbidity: 48.0% (95% confidence interval [CI] = 46.1% to 49.9%) of annual screeners aged 66 to 74 years had a false-positive result compared with 29.0% (95% CI = 28.1% to 29.9%) of biennial screeners. Conclusion Women aged 66 to 89 years who undergo biennial screening mammography have similar risk of advanced-stage disease and lower cumulative risk of a false-positive recommendation than annual screeners, regardless of comorbidity.

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

    Science.gov (United States)

    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.

  13. Uptake of 131-I in maxillary bones mimicking salivary glands. False- positive images in patients with differentiated thyroid carcinoma (DTC )

    International Nuclear Information System (INIS)

    Degrossi, Osvaldo J.; Degrossi, E.B.; Levi de Cabrejas, Mariana

    2008-01-01

    with the intensity of the administered activity of radioiodine, the previous condition of dental integrity and in patients living in the interior of our country in zones of 'bad' water containing tracers of arsenic and fluorine. In 13 patients submitted to intense treatment of dental problems posterior WBS showed a decrease of the positive maxilla areas or they were not found. The presence of metastasis in the active maxilla area was in all cases negative. Our observations confirm that radioiodine is deposited in maxillary bone in relation of dental lesions and that this 131-I move in a very slow place. This mechanism of fixation has to be determined. We fully recommended taking into account the existence of dental illness or incomplete dental treatments when the administration of higher activities than 3.7 GBq (150 mCi). (author) [es

  14. False-positive serology following intravenous immunoglobulin and plasma exchange through transfusion of fresh frozen plasma in a patient with pemphigus vulgaris.

    Science.gov (United States)

    Nomura, Hisashi; Honda, Haruki; Egami, Shohei; Yokoyama, Tomoaki; Fujimoto, Atsushi; Ishikawa, Makiko; Sugiura, Makoto

    2015-04-01

    Intravenous immunoglobulin therapy and plasma exchange through transfusion of fresh frozen plasma are therapeutic options for patients with refractory pemphigus vulgaris. Passive acquisition of various clinically important antibodies through these therapies can occur, leading to false serology and negatively affecting patients' clinical care. It is recommended that dermatologists recognize the possibility of these phenomena and interpret them appropriately. Here, we report false-positive serology following intravenous immunoglobulin therapy and plasma exchange through transfusion of fresh frozen plasma in a patient with refractory pemphigus vulgaris. We also discuss the measure for misinterpretation and unnecessary clinical intervention. © 2015 Japanese Dermatological Association.

  15. Newborn screening for carnitine palmitoyltransferase II deficiency using (C16+C18:1)/C2: Evaluation of additional indices for adequate sensitivity and lower false-positivity.

    Science.gov (United States)

    Tajima, Go; Hara, Keiichi; Tsumura, Miyuki; Kagawa, Reiko; Okada, Satoshi; Sakura, Nobuo; Maruyama, Shinsuke; Noguchi, Atsuko; Awaya, Tomonari; Ishige, Mika; Ishige, Nobuyuki; Musha, Ikuma; Ajihara, Sayaka; Ohtake, Akira; Naito, Etsuo; Hamada, Yusuke; Kono, Tomotaka; Asada, Tomoko; Sasai, Hideo; Fukao, Toshiyuki; Fujiki, Ryoji; Ohara, Osamu; Bo, Ryosuke; Yamada, Kenji; Kobayashi, Hironori; Hasegawa, Yuki; Yamaguchi, Seiji; Takayanagi, Masaki; Hata, Ikue; Shigematsu, Yosuke; Kobayashi, Masao

    2017-11-01

    Carnitine palmitoyltransferase (CPT) II deficiency is one of the most common forms of mitochondrial fatty acid oxidation disorder (FAOD). However, newborn screening (NBS) for this potentially fatal disease has not been established partly because reliable indices are not available. We diagnosed CPT II deficiency in a 7-month-old boy presenting with hypoglycemic encephalopathy, which apparently had been missed in the NBS using C16 and C18:1 concentrations as indices. By referring to his acylcarnitine profile from the NBS, we adopted the (C16+C18:1)/C2 ratio (cutoff 0.62) and C16 concentration (cutoff 3.0nmol/mL) as alternative indices for CPT II deficiency such that an analysis of a dried blood specimen collected at postnatal day five retroactively yielded the correct diagnosis. Thereafter, positive cases were assessed by measuring (1) the fatty acid oxidation ability of intact lymphocytes and/or (2) CPT II activity in the lysates of lymphocytes. The diagnoses were then further confirmed by genetic analysis. The disease was diagnosed in seven of 21 newborns suspected of having CPT II deficiency based on NBS. We also analyzed the false-negative patient and five symptomatic patients for comparison. Values for the NBS indices of the false-negative, symptomatic patient were lower than those of the seven affected newborns. Although it was difficult to differentiate the false-negative patient from heterozygous carriers and false-positive subjects, the fatty acid oxidation ability of the lymphocytes and CPT II activity clearly confirmed the diagnosis. Among several other indices proposed previously, C14/C3 completely differentiated the seven NBS-positive patients and the false-negative patient from the heterozygous carriers and the false-positive subjects. Genetic analysis revealed 16 kinds of variant alleles. The most prevalent, detected in ten alleles in nine patients from eight families, was c.1148T>A (p.F383Y), a finding in line with those of several previous reports on

  16. False positive of the scintigraphy with octreoscan: a diagnosis of elimination; Faux positif de la scintigraphie a l'octreoscan: un diagnostic d'elimination

    Energy Technology Data Exchange (ETDEWEB)

    Charrier, N.; Brenot-Rossi, I.; Chuto, G.; Giovannini, M.; Delpero, J.R. [Institut Paoli-Calmettes, Marseille, (France)

    2009-05-15

    The imaging of receptors with somatostatin analogs by the pentetreotide-indium 111 (octreoscan) allows the detection of endocrine tumors essentially according to the density of S.S.T.2 receptors at the tumor level. The sensitivity of octreoscan for the detection of intestine endocrine tumors is included between 80 and 100% in the different studies. The clinical case presented here enlightens a case of false positive.We concluded to a physiological elimination of pentetreotide-indium 111 with intra pancreatic biliary stasis (perhaps a dysfunction of sphincter of ampulla of bile duct) and to the lack of tumor centre. It is here a diagnosis of elimination, supported by the different results of examination. all normal. This case of false positive induced expensive and traumatic explorations for the patient. (N.C.)

  17. Patched Targeting Peptides for Imaging and Treatment of Hedgehog Positive Breast Tumors

    Directory of Open Access Journals (Sweden)

    Daniel Smith

    2014-01-01

    Full Text Available High tumor hedgehog expression is correlated with poor prognosis in invasive ductal carcinoma. Peptides which bind the patched receptor have recently been reported to have a growth inhibitory effect in tumors with activated hedgehog signaling. We sought to examine growth inhibition with these peptides in breast cancer cells and use these peptides as molecular imaging probes to follow changes in hedgehog expression after chemotherapy. Significant growth inhibition was observed in breast cancer cell lines treated with PTCH-blocking peptides. Significant in vitro uptake was observed with both FITC- and 99mTc-EC-peptide conjugates. In vivo imaging studies displayed greater accumulation of 99mTc-labeled peptides within tumors as compared to adjacent muscle tissue. Patched receptor expression increased after treatment and this correlated with an increase in tumor radiotracer uptake. These studies suggest that peptides which bind the sonic hedgehog docking site in patched receptor correlate with patched expression and can be used to image patched in vivo. Further, our data suggest that radiolabeled peptides may enable us to examine the activity of the hedgehog signaling pathway and to evaluate response to anti-cancer therapies.

  18. Molecular View of the Role of Fusion Peptides in Promoting Positive Membrane Curvature

    NARCIS (Netherlands)

    Fuhrmans, Marc; Marrink, Siewert J.

    2012-01-01

    Fusion peptides are moderately hydrophobic segments of viral and nonviral membrane fusion proteins that enable these proteins to fuse two closely apposed biological membranes. In vitro assays furthermore show that even isolated fusion peptides alone can support membrane fusion in model systems. In

  19. Prevalence, Long-term Development, and Predictors of Psychosocial Consequences of False-Positive Mammography among Women Attending Population-Based Screening.

    Science.gov (United States)

    Bolejko, Anetta; Hagell, Peter; Wann-Hansson, Christine; Zackrisson, Sophia

    2015-09-01

    Cancer screening aims to detect cancer at an asymptomatic stage, although side effects from screening also occur. We investigated the prevalence, longitudinal development, and predictors of psychosocial consequences of false-positive breast cancer screening. Three hundred ninety-nine women with false-positive screening mammography responded to the Consequences of Screening-Breast Cancer (COS-BC) questionnaire immediately after a negative diagnosis (free from breast cancer) following recall examination(s) (baseline), and 6 and 12 months later. Age-matched controls (n = 499) with a negative mammogram responded to the COS-BC at the same occasions. Five COS-BC scales (Sense of dejection, Anxiety, Behavioral, Sleep, and Existential values) were used as outcome measures. Women with false-positive mammography had consistently higher prevalence of all five consequences compared with controls (P consequences for all five outcomes (OR, 3.05-10.31), along with dissatisfaction with information at recall (OR, 2.28-2.56), being foreign-born (OR, 2.35-3.71), and lack of social support (OR, 1.13-1.25). This 1-year longitudinal study shows that women experience psychosocial consequences of false-positive screening mammography. Early recall should be performed cautiously, and provision of information as well as social support may reduce psychosocial consequences. Although delivery of population-based screening reduces breast cancer mortality, it also raises the issue of its impact on the psychosocial well-being of healthy women. Our findings identify predictors that can be targeted in future efforts to reduce the side effects of mammographic screening. ©2015 American Association for Cancer Research.

  20. Problems of false positive laboratory tests during qualification to the ”Program of severe plaque psoriasis treatment” on the basis of two cases

    OpenAIRE

    Dorota Jaśkiewicz-Nyckowska; Aneta Szczerkowska-Dobosz; Maria Czubek; Dorota Purzycka-Bohdan

    2015-01-01

    Introduction. Qualification of patients for the therapeutic program of severe plaque psoriasis should be preceded by many tests. Abnormal test results require further evaluation and possibly implementation of treatment. False positive results lead to prolongation of the qualification process and may cause disqualification of the patient. Objective. To draw attention to qualification to a drug program. Case reports . A screening test for Lyme disease performed in a 45-year-old man...

  1. Image findings of a false positive radioactive iodine-131 uptake mimicking metastasis in pulmonary aspergillosis identified on single photon emission computed tomography-computed tomography

    Directory of Open Access Journals (Sweden)

    Kamaleshwaran Koramadai Karuppusamy

    2015-01-01

    Full Text Available High doses of iodine-131 are commonly used in patients with differentiated thyroid cancer after total or subtotal thyroidectomy, in order to ablate the remaining cancer or normal thyroid tissue. Multiple different false-positive scans can occur in the absence of residual thyroid tissue or metastases. The authors present a case of abnormal uptake of radioactive iodine in the aspergilloma, potentially masquerading as pulmonary metastases.

  2. 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.

    Science.gov (United States)

    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

  3. Prediction of twin-arginine signal peptides

    DEFF Research Database (Denmark)

    Bendtsen, Jannick Dyrløv; Nielsen, Henrik; Widdick, D.

    2005-01-01

    a publicly available method, TatP, for prediction of bacterial Tat signal peptides. Results: We have retrieved sequence data for Tat substrates in order to train a computational method for discrimination of Sec and Tat signal peptides. The TatP method is able to positively classify 91% of 35 known Tat signal...... peptides and 84% of the annotated cleavage sites of these Tat signal peptides were correctly predicted. This method generates far less false positive predictions on various datasets than using simple pattern matching. Moreover, on the same datasets TatP generates less false positive predictions than...... expressions, whereas hydrophobicity discrimination of Tat- and Sec- signal peptides is carried out by an artificial neural network. A potential cleavage site of the predicted Tat signal peptide is also reported. The TatP prediction server is available as a public web server at http://www.cbs.dtu.dk/services/TatP/....

  4. Proportion of false-positive lesions at interim and end-of-treatment FDG-PET in lymphoma as determined by histology: Systematic review and meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Hugo J.A., E-mail: h.j.a.adams@gmail.com; Kwee, Thomas C.

    2016-11-15

    Purpose: To systematically review and meta-analyze the proportion of false-positive lesions at interim and end-of-treatment {sup 18}F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in lymphoma using biopsy as reference standard. Materials and methods: Medline was searched for original studies. Methodological quality of included studies was evaluated, and results were meta-analytically summarized using random effects (in case of interstudy heterogeneity [I{sup 2} ≤ 50%]) or fixed effects (in case of no interstudy heterogeneity [I{sup 2} > 50%]). Results: Eleven studies, comprising 139 patients who underwent biopsy of an FDG-avid lesion during or after completion of antilymphoma treatment, were included. Overall methodological quality was moderate. The proportion of false-positive results among all biopsied FDG-avid lesions at PET performed during of after completion of treatment ranged between 7.7% and 90.5% (the vast majority was due to inflammatory changes), with a weighted summary proportion (random effects, I{sup 2} = 75.7%) of 55.7% (95% confidence interval [CI]: 32.6–76.6%). There were no available studies on interim FDG-PET in Hodgkin lymphoma. The pooled summary false-positive proportions were 83.0% (95% CI: 72.0%–90.2%) for interim FDG-PET in non-Hodgkin lymphoma (fixed effects, I{sup 2} = 27.7%), 23.1% (95% CI: 4.7%–64.5%) for end-of-treatment FDG-PET in Hodgkin lymphoma (random effects; I{sup 2} = 67.1%), and 31.5% (95% CI: 3.9%–83.9%) for end-of-treatment FDG-PET in non-Hodgkin lymphoma (random effects, I{sup 2} = 68.3%). Conclusion: Both interim and end-of-treatment FDG-PET scans in patients with lymphoma suffer from a very high number of false-positive FDG-avid lesions. This finding, in combination with the previously reported high number of false-negative FGD-PET scans for residual disease detection, suggests that the role of interim and end-of-treatment FDG-PET should be reconsidered.

  5. Proportion of false-positive lesions at interim and end-of-treatment FDG-PET in lymphoma as determined by histology: Systematic review and meta-analysis

    International Nuclear Information System (INIS)

    Adams, Hugo J.A.; Kwee, Thomas C.

    2016-01-01

    Purpose: To systematically review and meta-analyze the proportion of false-positive lesions at interim and end-of-treatment 18 F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in lymphoma using biopsy as reference standard. Materials and methods: Medline was searched for original studies. Methodological quality of included studies was evaluated, and results were meta-analytically summarized using random effects (in case of interstudy heterogeneity [I 2 ≤ 50%]) or fixed effects (in case of no interstudy heterogeneity [I 2 > 50%]). Results: Eleven studies, comprising 139 patients who underwent biopsy of an FDG-avid lesion during or after completion of antilymphoma treatment, were included. Overall methodological quality was moderate. The proportion of false-positive results among all biopsied FDG-avid lesions at PET performed during of after completion of treatment ranged between 7.7% and 90.5% (the vast majority was due to inflammatory changes), with a weighted summary proportion (random effects, I 2 = 75.7%) of 55.7% (95% confidence interval [CI]: 32.6–76.6%). There were no available studies on interim FDG-PET in Hodgkin lymphoma. The pooled summary false-positive proportions were 83.0% (95% CI: 72.0%–90.2%) for interim FDG-PET in non-Hodgkin lymphoma (fixed effects, I 2 = 27.7%), 23.1% (95% CI: 4.7%–64.5%) for end-of-treatment FDG-PET in Hodgkin lymphoma (random effects; I 2 = 67.1%), and 31.5% (95% CI: 3.9%–83.9%) for end-of-treatment FDG-PET in non-Hodgkin lymphoma (random effects, I 2 = 68.3%). Conclusion: Both interim and end-of-treatment FDG-PET scans in patients with lymphoma suffer from a very high number of false-positive FDG-avid lesions. This finding, in combination with the previously reported high number of false-negative FGD-PET scans for residual disease detection, suggests that the role of interim and end-of-treatment FDG-PET should be reconsidered.

  6. Next-generation sequencing indicates false-positive MRD results and better predicts prognosis after SCT in patients with childhood ALL.

    Science.gov (United States)

    Kotrova, M; van der Velden, V H J; van Dongen, J J M; Formankova, R; Sedlacek, P; Brüggemann, M; Zuna, J; Stary, J; Trka, J; Fronkova, E

    2017-07-01

    Minimal residual disease (MRD) monitoring via quantitative PCR (qPCR) detection of Ag receptor gene rearrangements has been the most sensitive method for predicting prognosis and making post-transplant treatment decisions for patients with ALL. Despite the broad clinical usefulness and standardization of this method, we and others have repeatedly reported the possibility of false-positive MRD results caused by massive B-lymphocyte regeneration after stem cell transplantation (SCT). Next-generation sequencing (NGS) enables precise and sensitive detection of multiple Ag receptor rearrangements, thus providing a more specific readout compared to qPCR. We investigated two cohorts of children with ALL who underwent SCT (30 patients and 228 samples). The first cohort consisted of 17 patients who remained in long-term CR after SCT despite having low MRD positivity (SCT monitoring using qPCR. Only one of 27 qPCR-positive samples was confirmed to be positive by NGS. Conversely, 10 of 15 samples with low qPCR-detected MRD positivity from 13 patients who subsequently relapsed were also confirmed to be positive by NGS (P=0.002). These data show that NGS has a better specificity in post-SCT ALL management and indicate that treatment interventions aimed at reverting impending relapse should not be based on qPCR only.

  7. Comparison of false positive rates for screening breast magnetic resonance imaging (MRI) in high risk women performed on stacked versus alternating schedules

    OpenAIRE

    Othman, Edress; Wang, Jue; Sprague, Brian L; Rounds, Tiffany; Ji, YongLi; Herschorn, Sally D; Wood, Marie E

    2015-01-01

    Purpose Breast MRI added to mammography increases screening sensitivity for high-risk women but false-positive (FP) rates are higher and the optimal screening schedule for coordination with mammography is unclear. We compare rates of FP MRI when studies were performed on two different schedules. Patients and methods High-risk women at the University of Vermont who had at least 1 MRI and 1 mammogram performed within one year between 2004?2012 were eligible for inclusion in this study. Screenin...

  8. False-positive radioactive iodine uptake mimicking miliary lung metastases in a patient affected by papillary thyroid cancer and IgA deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Demidowich, Andrew Paul; Reynolds, James C. [National Institutes of Health, Bethesda (United States); Kundu, Amartya [Dept. of MedicineUniversity of Massachusetts Medical School, Worcester (United States); Celi, Francesco S. [Div. of Endocrinology and MetabolismVirginia Commonwealth UniversityRichmond (United States)

    2016-09-15

    A 42-year-old female with immunoglobulin A deficiency and recurrent sinopulmonary infections underwent thyroidectomy for papillary thyroid cancer (PTC). Follow-up {sup 123}I scintigraphy demonstrated diffuse pulmonary uptake, suggesting metastatic disease. However, subsequent pathologic, biochemical and radiographic testing proved that she was in fact disease free, and the initial {sup 123}I pulmonary uptake was identified as a false positive. Inflammatory conditions may rarely cause iodine uptake in non-thyroidal tissues due to local retention, organification, and/or immunologic utilization. To avoid exposing patients to unnecessary treatments, it is critical for clinicians to recognize that comorbid pulmonary conditions may mimic metastatic PTC on radioiodine scintigraphy.

  9. Massive training artificial neural network (MTANN) for reduction of false positives in computerized detection of lung nodules in low-dose computed tomography

    International Nuclear Information System (INIS)

    Suzuki, Kenji; Armato, Samuel G. III; Li, Feng; Sone, Shusuke; Doi, Kunio

    2003-01-01

    In this study, we investigated a pattern-recognition technique based on an artificial neural network (ANN), which is called a massive training artificial neural network (MTANN), for reduction of false positives in computerized detection of lung nodules in low-dose computed tomography (CT) images. The MTANN consists of a modified multilayer ANN, which is capable of operating on image data directly. The MTANN is trained by use of a large number of subregions extracted from input images together with the teacher images containing the distribution for the 'likelihood of being a nodule'. The output image is obtained by scanning an input image with the MTANN. The distinction between a nodule and a non-nodule is made by use of a score which is defined from the output image of the trained MTANN. In order to eliminate various types of non-nodules, we extended the capability of a single MTANN, and developed a multiple MTANN (Multi-MTANN). The Multi-MTANN consists of plural MTANNs that are arranged in parallel. Each MTANN is trained by using the same nodules, but with a different type of non-nodule. Each MTANN acts as an expert for a specific type of non-nodule, e.g., five different MTANNs were trained to distinguish nodules from various-sized vessels; four other MTANNs were applied to eliminate some other opacities. The outputs of the MTANNs were combined by using the logical AND operation such that each of the trained MTANNs eliminated none of the nodules, but removed the specific type of non-nodule with which the MTANN was trained, and thus removed various types of non-nodules. The Multi-MTANN consisting of nine MTANNs was trained with 10 typical nodules and 10 non-nodules representing each of nine different non-nodule types (90 training non-nodules overall) in a training set. The trained Multi-MTANN was applied to the reduction of false positives reported by our current computerized scheme for lung nodule detection based on a database of 63 low-dose CT scans (1765

  10. High prevalence of human anti-bovine IgG antibodies as the major cause of false positive reactions in two-site immunoassays based on monoclonal antibodies

    DEFF Research Database (Denmark)

    Andersen, Ditte C; Koch, Claus; Jensen, Charlotte H

    2004-01-01

    were purified by protein G affinity chromatography from culture supernatant containing 10% (v/v) fetal calf serum (FCS). Human anti-animal IgG (bovine, mouse, horse, and swine) antibodies and human anti-bovine serum albumin antibodies were measured using an ELISA design, with direct bridging...... of the solid phase and biotinylated antigens. The false positive reactions were abolished by addition of 1% (v/v) bovine serum to the dilution buffer (DB). Human anti-bovine IgG antibodies (HABIA) were detected in 99 out of 104 sera from blood donors (50 females; 54 males). HABIA levels in male sera (n = 54...... positively correlated to human anti-bovine serum albumin antibodies in the donor sera (r = 0.639; p

  11. Atrial Natriuretic Peptide and Renal Dopaminergic System: A Positive Friendly Relationship?

    Directory of Open Access Journals (Sweden)

    Marcelo Roberto Choi

    2014-01-01

    Full Text Available Sodium metabolism by the kidney is accomplished by an intricate interaction between signals from extrarenal and intrarenal sources and between antinatriuretic and natriuretic factors. Renal dopamine plays a central role in this interactive network. The natriuretic hormones, such as the atrial natriuretic peptide, mediate some of their effects by affecting the renal dopaminergic system. Renal dopaminergic tonus can be modulated at different steps of dopamine metabolism (synthesis, uptake, release, catabolism, and receptor sensitization which can be regulated by the atrial natriuretic peptide. At tubular level, dopamine and atrial natriuretic peptide act together in a concerted manner to promote sodium excretion, especially through the overinhibition of Na+, K+-ATPase activity. In this way, different pathological scenarios where renal sodium excretion is dysregulated, as in nephrotic syndrome or hypertension, are associated with impaired action of renal dopamine and/or atrial natriuretic peptide, or as a result of impaired interaction between these two natriuretic systems. The aim of this review is to update and comment on the most recent evidences demonstrating how the renal dopaminergic system interacts with atrial natriuretic peptide to control renal physiology and blood pressure through different regulatory pathways.

  12. Significance of FDG-PET in Identification of Diseases of the Appendix – Based on Experience of Two Cases Falsely Positive for FDG Accumulation

    Directory of Open Access Journals (Sweden)

    Shimpei Ogawa

    2009-04-01

    Full Text Available A discussion of the significance of F-fluorodeoxyglucose positron emission tomography (FDG-PET in the identification of diseases of the appendix is presented based on two cases falsely positive for FDG accumulation. Both cases were palpable for a tumor in the lower right abdominal region and a prominently enlarged appendix was depicted by CT. Although the patients underwent ileocecal resection based on a strong suspicion of appendiceal cancer rather than appendicitis since abnormal accumulation exhibiting maximum standard uptake values (SUVs of 7.27 and 17.11, respectively, was observed at the same site in FDG-PET examination and since there no malignant findings observed histologically, the patients were diagnosed with appendicitis. Although FDG specifically accumulates not only in malignant tumors, but also in diseases such as acute or chronic inflammation, abscesses and lymphadenitis, and identification based on SUVs has been reported to be used as a method of identification, the two cases reported here were both false-positive cases exhibiting high maximum SUVs. At the present time, although the significance of FDG-PET in the identification of diseases of the appendix is somewhat low and there are limitations on its application, various research is currently being conducted with the aim of improving diagnostic accuracy, and it is hoped that additional studies will be conducted in the future.

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

    Science.gov (United States)

    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

  14. Aromatic residue position on the nonpolar face of class a amphipathic helical peptides determines biological activity.

    Science.gov (United States)

    Datta, Geeta; Epand, Raquel F; Epand, Richard M; Chaddha, Manjula; Kirksey, Matthew A; Garber, David W; Lund-Katz, Sissel; Phillips, Michael C; Hama, Susan; Navab, Mohamad; Fogelman, Alan M; Palgunachari, Mayakonda N; Segrest, Jere P; Anantharamaiah, G M

    2004-06-18

    The apolipoprotein A-I mimetic peptide 4F (Ac-DWFKAFYDKVAEKFKEAF-NH(2)), with four Phe residues on the nonpolar face of the amphipathic alpha-helix, is strongly anti-inflammatory, whereas two 3F analogs (3F(3) and 3F(14)) are not. To understand how changes in helix nonpolar face structure affect function, two additional 3F analogs, Ac-DKLKAFYDKVFEWAKEAF-NH(2) (3F-1) and Ac-DKWKAVYDKFAEAFKEFL-NH(2) (3F-2), were designed using the same amino acid composition as 3F(3) and 3F(14). The aromatic residues in 3F-1 and 3F-2 are near the polar-nonpolar interface and at the center of the nonpolar face of the helix, respectively. Like 4F, but in contrast to 3F(3) and 3F(14), these peptides effectively inhibited lytic peptide-induced hemolysis, oxidized phospholipid-induced monocyte chemotaxis, and scavenged lipid hydroperoxides from low density lipoprotein. High pressure liquid chromatography retention times and monolayer exclusion pressures indicated that there is no direct correlation of peptide function with lipid affinity. Fluorescence studies suggested that, although the peptides bind phospholipids similarly, the Trp residue in 4F, 3F-1, and 3F-2 is less motionally restricted than in 3F(3) and 3F(14). Based on these results and molecular modeling studies, we propose that the arrangement of aromatic residues in class A amphipathic helical molecules regulates entry of reactive oxygen species into peptide-phospholipid complexes, thereby reducing the extent of monocyte chemotaxis, an important step in atherosclerosis.

  15. Strong combined gene-environment effects in anti-cyclic citrullinated peptide-positive rheumatoid arthritis

    DEFF Research Database (Denmark)

    Pedersen, Line Merete Blak; Jacobsen, Søren; Garred, Peter

    2007-01-01

    To study the role of shared epitope (SE) susceptibility genes, alone and in combination with tobacco smoking and other environmental risk factors, for risk of subtypes of rheumatoid arthritis (RA) defined by the presence or absence of serum antibodies against cyclic citrullinated peptides (CCPs)....

  16. The 4-pyridylmethyl ester as a protecting group for glutamic and aspartic acids: 'flipping' peptide charge states for characterization by positive ion mode ESI-MS.

    Science.gov (United States)

    Garapati, Sriramya; Burns, Colin S

    2014-03-01

    Use of the 4-pyridylmethyl ester group for side-chain protection of glutamic acid residues in solid-phase peptide synthesis enables switching of the charge state of a peptide from negative to positive, thus making detection by positive ion mode ESI-MS possible. The pyridylmethyl ester moiety is readily removed from peptides in high yield by hydrogenation. Combining the 4-pyridylmethyl ester protecting group with benzyl ester protection reduces the number of the former needed to produce a net positive charge and allows for purification by RP HPLC. This protecting group is useful in the synthesis of highly acidic peptide sequences, which are often beset by problems with purification by standard RP HPLC and characterization by ESI-MS. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.

  17. The Relations Between False Positive and Negative Screens and Smoking Cessation and Relapse in the National Lung Screening Trial: Implications for Public Health.

    Science.gov (United States)

    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.

  18. Usefulness of pulse-wave doppler tissue sampling and dobutamine stress echocardiography for identification of false positive inferior wall defects in SPECT

    International Nuclear Information System (INIS)

    Altinmakas, S.; Dagdeviren, B.; Turkmen, M.; Gursurer, M.; Say, B.; Tezel, T.; Ersek, B.

    2000-01-01

    False positive inferior wall perfusion defects restrict the accuracy of SPECT in diagnosis of coronary artery disease (CAD). Pulse-Wave Tissue Doppler (PWTD) has been recently proposed to assess regional wall motion velocities. The objectives of this study were to evaluate the presence of CAD by using PWTD during dobutamine stress echocardiography (DSE) in patients with an inferior perfusion defect detected by SPECT and compare PWTD parameters of normal cases with patients who had inferior perfusion defect and CAD. Sixty-five patients (mean age 58±8 years, 30 men) with a normal LV systolic function at rest according to echocardiographic evaluation with an inferior ischemia determined by SPECT and a control group (CG) of 34 normal cases (mean age 56±7 years, 16 men) were included in this study. All patients underwent a standard DSE (up to 40 μg/kg/min with additional atropine during sub-maximum heart rate responses). Pulse-wave Doppler tissue sampling of inferior wall was performed in the apical 2-chamber view at rest and stress. The coronary angiography was performed within 24 hours. The results were evaluated for the prediction of significant right coronary artery (RCA) and/or left circumflex coronary artery (CX) with narrowing (≥50% diameter stenosis, assessed by quantitative coronary angiography). It was observed that the peak stress mean E/A ratio was lower in patients with CAD when compared to patients without CAD (0.78±0.2 versus 1.29±0.11 p<0.0001). Also the peak stress E/A ratio of normal cases was significantly higher than patients who had CAD (1.19±0.3 versus 0.78±0.2 p<0.0001). When the cut off point for the E/A ratio was determined as 1, the sensitivity and specificity of dobutamine stress PWTD E/A were 89% and 86%, respectively. The peak stress E/A ratio was higher than 1 in all patients with a false positive perfusion defect. Systolic S velocity increase during DSE was significantly lower in patients with CAD (54%±17 versus 99%±24 p=0

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

    Science.gov (United States)

    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.

  20. Antitumor potential of a synthetic interferon-alpha/PLGF-2 positive charge peptide hybrid molecule in pancreatic cancer cells.

    Science.gov (United States)

    Yin, Hongmei; Chen, Naifei; Guo, Rui; Wang, Hong; Li, Wei; Wang, Guanjun; Cui, Jiuwei; Jin, Haofan; Hu, Ji-Fan

    2015-11-20

    Pancreatic cancer is the most aggressive malignant disease, ranking as the fourth leading cause of cancer-related death among men and women in the United States. Interferon alpha (IFNα) has been used to treat pancreatic cancer, but its clinical application has been significantly hindered due to the low antitumor activity. We used a "cDNA in-frame fragment library" screening approach to identify short peptides that potentiate the antitumor activity of interferons. A short positively charged peptide derived from the C-terminus of placental growth factor-2 (PLGF-2) was selected to enhance the activity of IFNα. For this, we constructed a synthetic interferon hybrid molecule (SIFα) by fusing the positively charged PLGF-2 peptide to the C-terminus of the human IFNα. Using human pancreatic cell lines (ASPC and CFPAC1) as a model system, we found that SIFα exhibited a significantly higher activity than did the wild-type IFNα in inhibiting the tumor cell growth. The enhanced activity of the synthetic SIFα was associated with the activation of interferon pathway target genes and the increased binding of cell membrane receptor. This study demonstrates the potential of a synthetic SIFα as a novel antitumor agent.

  1. False positive serum levels of (1-3)-ß-D-Glucan after infusion of intravenous immunoglobulins and time to normalisation.

    Science.gov (United States)

    Egger, M; Prüller, F; Raggam, R; Divjak, M K; Kurath-Koller, S; Lackner, H; Urban, C; Strenger, V

    2018-02-01

    (1-3)-ß-D-Glucan (BDG) is a marker for invasive fungal diseases (IFD). Administration of intravenous immunoglobulin preparations (IVIG) has been reported to lead to false positive BDG serum levels >80 pg/ml. The aim of the study was to determine the time interval between IVIG infusion and normalisation of BDG serum levels. In 22 paediatric haemato-/oncologic patients, we analysed 92 BDG serum levels obtained within 4 weeks after IVIG administration (0.5 to 1 g/kg body weight), correlated them to 54 IVIG episodes and compared them to 76 BDG levels obtained in 29 patients without IVIG administration in the 4 weeks prior to BDG analyses (control group). BDG peak levels within 3 days after IVIG ranged from 21.47 to 660.38 (median 201.4) pg/ml. BDG serum levels at 7, 14 and 21 days (+/-1 day each) after IVIG infusion were significantly higher than BDG serum levels in the control group (p < 0.001 each). By days 7, 14, and 21 (+/-1 day each) after IVIG infusion, BDG serum levels have normalized (<80 pg/ml) in 64.0%, 76.5% and 100%, respectively. IVIG administration leads to false positive BDG levels in the vast majority of patients. Elevated BDG levels may be detectable for more than two weeks after IVIG administration, while BDG levels normalized within 3 weeks in all patients. Therefore, BDG should not be used to diagnose IFD within three weeks after IVIG administration. Copyright © 2017 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

  3. Prediction of twin-arginine signal peptides

    Directory of Open Access Journals (Sweden)

    Widdick David

    2005-07-01

    Full Text Available Abstract Background Proteins carrying twin-arginine (Tat signal peptides are exported into the periplasmic compartment or extracellular environment independently of the classical Sec-dependent translocation pathway. To complement other methods for classical signal peptide prediction we here present a publicly available method, TatP, for prediction of bacterial Tat signal peptides. Results We have retrieved sequence data for Tat substrates in order to train a computational method for discrimination of Sec and Tat signal peptides. The TatP method is able to positively classify 91% of 35 known Tat signal peptides and 84% of the annotated cleavage sites of these Tat signal peptides were correctly predicted. This method generates far less false positive predictions on various datasets than using simple pattern matching. Moreover, on the same datasets TatP generates less false positive predictions than a complementary rule based prediction method. Conclusion The method developed here is able to discriminate Tat signal peptides from cytoplasmic proteins carrying a similar motif, as well as from Sec signal peptides, with high accuracy. The method allows filtering of input sequences based on Perl syntax regular expressions, whereas hydrophobicity discrimination of Tat- and Sec-signal peptides is carried out by an artificial neural network. A potential cleavage site of the predicted Tat signal peptide is also reported. The TatP prediction server is available as a public web server at http://www.cbs.dtu.dk/services/TatP/.

  4. Identifying Non-Duchenne Muscular Dystrophy-Positive and False Negative Results in Prior Duchenne Muscular Dystrophy Newborn Screening Programs: A Review.

    Science.gov (United States)

    Gatheridge, Michele A; Kwon, Jennifer M; Mendell, Jerry M; Scheuerbrandt, Günter; Moat, Stuart J; Eyskens, François; Rockman-Greenberg, Cheryl; Drousiotou, Anthi; Griggs, Robert C

    2016-01-01

    Duchenne muscular dystrophy (DMD) is a candidate for the recommended universal screening panel based on evidence that early corticosteroid treatment improves outcomes and on new genetic therapies that require early diagnosis for effectiveness. Elevated creatine kinase levels in the neonatal period are the initial screening marker in DMD newborn screening programs but is found in inherited muscle disorders other than DMD. Data are needed to inform protocols for future screening and follow-up testing and care in these patients. To review non-DMD muscle disorders identified by prior DMD screening programs and to investigate whether these programs failed to identify patients later diagnosed as having DMD (false-negative findings). Since 1975, 10 DMD newborn screening programs have provided opportunities to study screening protocols, outcomes, and parental responses. These programs used elevated creatine kinase levels in dried blood spots for the initial screening, with the diagnosis of DMD based on findings of clinical follow-up, muscle biopsy, or direct mutational testing of the DMD gene. Literature regarding these prior programs was reviewed in PubMed, and the programs were discussed directly with the directors when possible to identify diagnoses of non-DMD disorders and false negative results from 1975 to July 12, 2015. Data were collected from screening programs, which were active between 1975 and December 2011. Data were analyzed from March 26, 2015, to August 24, 2015. The 10 screening programs screened more than 1.8 million newborns between 1975 and 2011, and 344 were diagnosed with DMD. Of those screened, the majority were boys. Across all programs, 80 patients had positive results for non-DMD disorders, including Becker muscular dystrophy and forms of limb-girdle and congenital muscular dystrophies, and 21 patients had false-negative findings for DMD. Screening for DMD will result in identification of other muscle diseases. Future screening protocols should

  5. Unsaturated fatty acids show clear elicitation responses in a modified local lymph node assay with an elicitation phase, and test positive in the direct peptide reactivity assay.

    Science.gov (United States)

    Yamashita, Kunihiko; Shinoda, Shinsuke; Hagiwara, Saori; Miyazaki, Hiroshi; Itagaki, Hiroshi

    2015-12-01

    The Organisation for Economic Co-operation and Development (OECD) Test Guidelines (TG) adopted the murine local lymph node assay (LLNA) and guinea pig maximization test (GPMT) as stand-alone skin sensitization test methods. However, unsaturated carbon-carbon double-bond and/or lipid acids afforded false-positive results more frequently in the LLNA compared to those in the GPMT and/or in human subjects. In the current study, oleic, linoleic, linolenic, undecylenic, fumaric, maleic, and succinic acid and squalene were tested in a modified LLNA with an elicitation phase (LLNA:DAE), and in a direct peptide reactivity assay (DPRA) to evaluate their skin-sensitizing potential. Oleic, linoleic, linolenic, undecylenic and maleic acid were positive in the LLNA:DAE, of which three, linoleic, linolenic, and maleic acid were positive in the DPRA. Furthermore, the results of the cross-sensitizing tests using four LLNA:DAE-positive chemicals were negative, indicating a chemical-specific elicitation response. In a previous report, the estimated concentration needed to produce a stimulation index of 3 (EC3) of linolenic acid, squalene, and maleic acid in the LLNA was undecylenic, and maleic acid had skin-sensitizing potential, and that the LLNA overestimated the skin-sensitizing potential compared to that estimated by the LLNA:DAE.

  6. Avian metapneumovirus RT-nested-PCR: a novel false positive reducing inactivated control virus with potential applications to other RNA viruses and real time methods.

    Science.gov (United States)

    Falchieri, Marco; Brown, Paul A; Catelli, Elena; Naylor, Clive J

    2012-12-01

    Using reverse genetics, an avian metapneumovirus (AMPV) was modified for use as a positive control for validating all stages of a popular established RT-nested PCR, used in the detection of the two major AMPV subtypes (A and B). Resultant amplicons were of increased size and clearly distinguishable from those arising from unmodified virus, thus allowing false positive bands, due to control virus contamination of test samples, to be identified readily. Absorption of the control virus onto filter paper and subsequent microwave irradiation removed all infectivity while its function as an efficient RT-nested-PCR template was unaffected. Identical amplicons were produced after storage for one year. The modified virus is likely to have application as an internal standard as well as in real time methods. Additions to AMPV of RNA from other RNA viruses, including hazardous examples such HIV and influenza, are likely to yield similar safe RT-PCR controls. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. 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.

    Science.gov (United States)

    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/

  8. Phase II Study of HER-2/Neu Intracellular Domain Peptide-Based Vaccine Administered to Stage IV HER2 Positive Breast Cancer Patients Receiving Trastuzumab

    National Research Council Canada - National Science Library

    Disis, Mary L

    2005-01-01

    .... This proposal outlines a Phase II clinical trial designed to estimate survival in Stage IV HER2 positive breast cancer patients with no evidence of disease and receiving trastuzumab and a HER2 ICD peptide based vaccine...

  9. Phase II Study of HER-2/neu Intracellular Domain Peptide-Based Vaccine Administered to Stage IV HER2 Positive Breast Cancer Patients Receiving Trastuzumab

    National Research Council Canada - National Science Library

    Disis, Mary L

    2006-01-01

    The primary purpose of this grant is to determine the overall survival benefit in Stage IV HER2 positive breast cancer patients vaccinated with a HER2 ICD peptide-based vaccine while receiving maintenance trastuzumab...

  10. Phase II Study of HER-2/neu Intracellular Domain Peptide-Based Vaccine Administered to Stage IV HER2 Positive Breast Cancer Patients Receiving Trastuzumab

    National Research Council Canada - National Science Library

    Disis, Mary L

    2007-01-01

    The primary purpose of this grant is to determine the overall survival benefit in Stage IV HER2 positive breast cancer patients vaccinated with a HER2 ICD peptide-based vaccine while receiving maintenance trastuzumab...

  11. Arginine-lysine positional swap of the LL-37 peptides reveals evolutional advantages of the native sequence and leads to bacterial probes.

    Science.gov (United States)

    Wang, Xiuqing; Junior, José Carlos Bozelli; Mishra, Biswajit; Lushnikova, Tamara; Epand, Richard M; Wang, Guangshun

    2017-08-01

    Antimicrobial peptides are essential components of the innate immune system of multicellular organisms. Although cationic and hydrophobic amino acids are known determinants of these amphipathic molecules for bacterial killing, it is not clear how lysine-arginine (K-R) positional swaps influence peptide structure and activity. This study addresses this question by investigating two groups of peptides (GF-17 and 17BIPHE2) derived from human cathelicidin LL-37. K-R positional swap showed little effect on minimal inhibitory concentrations of the peptides. However, there are clear differences in bacterial killing kinetics. The membrane permeation patterns vary with peptide and bacterial types, but not changes in fluorescent dyes, salts or pH. In general, the original peptide is more efficient in bacterial killing, but less toxic to human cells, than the K-R swapped peptides, revealing the evolutionary significance of the native sequence for host defense. The characteristic membrane permeation patterns for different bacteria suggest a possible application of these K-R positional-swapped peptides as molecular probes for the type of bacteria. Such differences are related to bacterial membrane compositions: minimal for Gram-positive Staphylococcus aureus with essentially all anionic lipids (cardiolipin and phosphatidylglycerol), but evident for Gram-negative Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli with a mixture of phosphatidylethanolamine and phosphatidylglycerol. Biophysical characterization found similar structures and binding affinities for these peptides in vesicle systems mimicking E. coli and S. aureus. It seems that interfacial arginines of GF-17 are preferred over lysines in bacterial membrane permeation. Our study sheds new light on the design of cationic amphipathic peptides. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Positive vs. false detection: a comparison of analytical methods and performance for analysis of cyclic volatile methylsiloxanes (cVMS) in environmental samples from remote regions.

    Science.gov (United States)

    Warner, Nicholas A; Kozerski, Gary; Durham, Jeremy; Koerner, Martin; Gerhards, Reinhard; Campbell, Roy; McNett, Debra A

    2013-10-01

    Contamination and analytical variation can significantly hinder trace analysis of cyclic methyl volatile siloxanes (cVMS); potentially resulting in the report of false positives at concentrations approaching detection limits. To assess detection and variation associated with trace cVMS analysis in environmental matrices, a co-operative laboratory comparison for the analysis of octametylcyclotetrasiloxane (D4), decamethylcylcopentasiloxane (D5), and dodecametylcyclohexasiloxane (D6) in sediment and biota from the Svalbard Archipelago was conducted. Two definitions of detection limits were evaluated in this study; method detection limits (MDL, matrix defined) and limits of detection (LOD, solvent defined). D5 was the only cVMS detected above both LOD (0.08-0.81ngg(-1)ww) and MDL (0.47-2.36ngg(-1)ww) within sediment by all laboratories where concentrations ranged from 0.55 to 3.91ngg(-1)ww. The percentage of positive detects for D5 decreased by 80% when MDL was defined as the detection limit. D5 was also detected at the highest frequency among all laboratories in fish liver with concentrations ranging from 0.72 to 345ngg(-1)ww. Similar to sediment, percentage of positive detects for D5 decreased by 60% across all laboratories for fish livers when using MDL (0.68-3.49ngg(-1)ww). Similar observations were seen with both D4 and D6, indicating that sample matrix significantly contributes to analytical response variation. Despite differences in analytical methods used between laboratories, good agreement was obtained when using MDL to define detection limits. This study shows the importance of incorporating variation introduced by sample matrices into detection limit calculations to insure data accuracy of cVMS at low concentrations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Massive-training artificial neural network (MTANN) for reduction of false positives in computer-aided detection of polyps: Suppression of rectal tubes

    International Nuclear Information System (INIS)

    Suzuki, Kenji; Yoshida, Hiroyuki; Naeppi, Janne; Dachman, Abraham H.

    2006-01-01

    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 may 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 texture

  14. Design, Synthesis and Evaluation of Branched RRWQWR-Based Peptides as Antibacterial Agents Against Clinically Relevant Gram-Positive and Gram-Negative Pathogens

    Directory of Open Access Journals (Sweden)

    Sandra C. Vega

    2018-03-01

    Full Text Available Multidrug resistance of pathogenic bacteria has become a public health crisis that requires the urgent design of new antibacterial drugs such as antimicrobial peptides (AMPs. Seeking to obtain new, lactoferricin B (LfcinB-based synthetic peptides as viable early-stage candidates for future development as AMPs against clinically relevant bacteria, we designed, synthesized and screened three new cationic peptides derived from bovine LfcinB. These peptides contain at least one RRWQWR motif and differ by the copy number (monomeric, dimeric or tetrameric and structure (linear or branched of this motif. They comprise a linear palindromic peptide (RWQWRWQWR, a dimeric peptide (RRWQWR2KAhx and a tetrameric peptide (RRWQWR4K2Ahx2C2. They were screened for antibacterial activity against Enterococcus faecalis (ATCC 29212 and ATCC 51575 strains, Pseudomonas aeruginosa (ATCC 10145 and ATCC 27853 strains and clinical isolates of two Gram-positive bacteria (Enterococcus faecium and Staphylococcus aureus and two Gram-negative bacteria (Klebsiella pneumoniae and Pseudomonas aeruginosa. All three peptides exhibited greater activity than did the reference peptide, LfcinB (17–31, which contains a single linear RRWQWR motif. Against the ATCC reference strains, the three new peptides exhibited minimum inhibitory concentration (MIC50 values of 3.1–198.0 μM and minimum bactericidal concentration (MBC values of 25–200 μM, and against the clinical isolates, MIC50 values of 1.6–75.0 μM and MBC values of 12.5–100 μM. However, the tetrameric peptide was also found to be strongly hemolytic (49.1% at 100 μM. Scanning Electron Microscopy (SEM demonstrated that in the dimeric and tetrameric peptides, the RRWQWR motif is exposed to the pathogen surface. Our results may inform the design of new, RRWQWR-based AMPs.

  15. 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

    Science.gov (United States)

    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 ...

  16. 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)

    Science.gov (United States)

    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 ...

  17. Toward the breast screening balance sheet: cumulative risk of false positives for annual versus biennial mammograms commencing at age 40 or 50.

    Science.gov (United States)

    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.

  18. Small intestinal bacterial overgrowth as an uncommon cause of false positive lactose hydrogen breath test among patients with diarrhea-predominant irritable bowel syndrome in Asia.

    Science.gov (United States)

    Wang, Yilin; Xiong, Lishou; Gong, Xiaorong; Li, Weimin; Zhang, Xiangsong; Chen, Minhu

    2015-06-01

    It has been reported that small intestinal bacterial overgrowth (SIBO) may lead to false positive diagnoses of lactose malabsorption (LM) in irritable bowel syndrome patients. The aim of this study was to determine the influence of SIBO on lactose hydrogen breath test (HBT) results in these patients. Diarrhea-predominant irritable bowel syndrome patients with abnormal lactose HBTs ingested a test meal containing (99m) Tc and lactose. The location of the test meal and the breath levels of hydrogen were recorded simultaneously by scintigraphic scanning and lactose HBT, respectively. The increase in hydrogen concentration was not considered to be caused by SIBO if ≥ 10% of (99m) Tc accumulated in the cecal region at the time or before of abnormal lactose HBT. LM was present in 84% (31/37) of irritable bowel syndrome patients. Twenty of these patients agreed to measurement of oro-cecal transit time. Only three patients (15%) with abnormal lactose HBT might have had SIBO. The median oro-cecal transit time between LM and lactose intolerance patients were 75 min and 45 min, respectively (Z=2.545, P=0.011). Most of irritable bowel syndrome patients with an abnormal lactose HBT had LM. SIBO had little impact on the interpretation of lactose HBTs. The patients with lactose intolerance had faster small intestinal transit than LM patients. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

  19. Respostas falso-positivas na triagem auditiva neonatal universal: possíveis causas False-positive results in newborn universal hearing screening: possible causes

    Directory of Open Access Journals (Sweden)

    Maria Cristina Silva Simonek

    2011-04-01

    Full Text Available OBJETIVO: avaliar a ocorrência de respostas falso-positivas na Triagem Auditiva dentro de uma maternidade particular, suas possíveis causas e soluções. MÉTODOS: foram avaliados 1.110 recém-nascidos eutróficos entre 6 e 48 horas de vida no berçário, com o analisador de Emissões Otoacústicas Evocadas Transientes (EOATE modelo Echochek da Ilodynamics Ltd. Na ausência de resposta, foi realizada a manipulação do meato acústico externo (Manobra Facilitadora e colhido novo resultado. Os que falharam foram retestados em 15 dias. RESULTADOS: 50,09% dos RN falhou na primeira tentativa. Após a manobra facilitadora, 24,41% continuou falhando, mas demonstraram EOATE presentes no reteste. O tempo médio de internação foi de 42,27 h, sendo 93,42% oriundos de cesareana. Pertenciam a convênios particulares padrão enfermaria 98% e 2% quarto individual. A idade média do grupo que passou foi de 24,14 h (± 10,21 e a do grupo que falhou 19,19 horas (±8,43. Possuíam menos de 24 horas de vida no momento do teste 66,12% dos RN, foi constatado vérnix obliterante em 4.9%. CONLUSÃO: face a alta precoce hospitalar, é necessário que o Fonoaudiólogo realize o teste antes das 48 horas de vida do RN. Desta forma, além das causas biológicas inerentes a faixa etária, detectou-se um problema estrutural de administração hospitalar, que independe da habilidade ou experiência do Fonoaudiólogo. A Manobra Facilitadora é altamente recomendada.PURPOSE: to investigate the rate of false positive responses in a hospital - based newborn hearing screening program (NHS, their possible causes and solutions. METHODS: during the period we evaluated 1,110 regular nursery newborns, age 6 to 48 hours with Transient Evoked Otoacoustic Emissions (TEOAEs, Echocheck, Ilodynamics Ltd model., at the nurseries, before discharge. In case of absence of response, the ear canal was manipulated. Infants that failed the screening were retested fifteen days after birth

  20. TEMPO-Assisted Free Radical-Initiated Peptide Sequencing Mass Spectrometry (FRIPS MS) in Q-TOF and Orbitrap Mass Spectrometers: Single-Step Peptide Backbone Dissociations in Positive Ion Mode

    Science.gov (United States)

    Jang, Inae; Lee, Sun Young; Hwangbo, Song; Kang, Dukjin; Lee, Hookeun; Kim, Hugh I.; Moon, Bongjin; Oh, Han Bin

    2017-01-01

    The present study demonstrates that one-step peptide backbone fragmentations can be achieved using the TEMPO [2-(2,2,6,6-tetramethyl piperidine-1-oxyl)]-assisted free radical-initiated peptide sequencing (FRIPS) mass spectrometry in a hybrid quadrupole time-of-flight (Q-TOF) mass spectrometer and a Q-Exactive Orbitrap instrument in positive ion mode, in contrast to two-step peptide fragmentation in an ion-trap mass spectrometer (reference Anal. Chem. 85, 7044-7051 (30)). In the hybrid Q-TOF and Q-Exactive instruments, higher collisional energies can be applied to the target peptides, compared with the low collisional energies applied by the ion-trap instrument. The higher energy deposition and the additional multiple collisions in the collision cell in both instruments appear to result in one-step peptide backbone dissociations in positive ion mode. This new finding clearly demonstrates that the TEMPO-assisted FRIPS approach is a very useful tool in peptide mass spectrometry research.

  1. 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.

    Directory of Open Access Journals (Sweden)

    Patrick Ndase

    Full Text Available 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.

  2. Computer-aided detection of microcalcification clusters on full-field digital mammograms: multiscale pyramid enhancement and false positive reduction using an artificial neural network

    Science.gov (United States)

    Ge, Jun; Wei, Jun; Hadjiiski, Lubomir M.; Sahiner, Berkman; Chan, Heang-Ping; Helvie, Mark A.; Zhou, Chuan

    2005-04-01

    We are developing a computer-aided detection (CAD) system to detect microcalcification clusters automatically on full field digital mammograms (FFDMs). The CAD system includes five stages: preprocessing, image enhancement and/or box-rim filtering, segmentation of microcalcification candidates, false positive (FP) reduction, and clustering. In this study, we investigated the performance of a nonlinear multiscale Laplacian pyramid enhancement method in comparison with a box-rim filter at the image enhancement stage and the use of a new error metric to improve the efficiency and robustness of the training of a convolution neural network (CNN) at the FP reduction stage of our CAD system. A data set of 96 cases with 200 images was collected at the University of Michigan. This data set contained 215 microcalcification clusters, of which 64 clusters were proven by biopsy to be malignant and 151 were proven to be benign. The data set was separated into two independent data sets. One data set was used to train and validate the CNN in our CAD system. The other data set was used to evaluate the detection performance. For this data set, Laplacian pyramid multiscale enhancement did not improve the performance of the microcalcification detection system in comparison with our box-rim filter previously optimized for digitized screen-film mammograms. With the new error metric, the training of CNN could be accelerated and the classification performance in validation was improved from an Az value of 0.94 to 0.97 on average. The CNN in combination with rule-based classifiers could reduce FPs with a small tradeoff in sensitivity. By using the free-response receiver operating characteristic (FROC) methodology, it was found that our CAD system can achieve a cluster-based sensitivity of 70%, 80%, and 88% at 0.23, 0.39, and 0.71 FP marks/image, respectively. For case-based performance evaluation, a sensitivity of 80%, 90%, and 98% can be achieved at 0.17, 0.27, and 0.51 FP marks

  3. Automated detection of pulmonary nodules in PET/CT images: Ensemble false-positive reduction using a convolutional neural network technique

    International Nuclear Information System (INIS)

    Teramoto, Atsushi; Fujita, Hiroshi; Yamamuro, Osamu; Tamaki, Tsuneo

    2016-01-01

    Purpose: Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be further reduced. In this paper, the authors propose an improved FP-reduction method for the detection of pulmonary nodules in PET/CT images by means of convolutional neural networks (CNNs). Methods: The overall scheme detects pulmonary nodules using both CT and PET images. In the CT images, a massive region is first detected using an active contour filter, which is a type of contrast enhancement filter that has a deformable kernel shape. Subsequently, high-uptake regions detected by the PET images are merged with the regions detected by the CT images. FP candidates are eliminated using an ensemble method; it consists of two feature extractions, one by shape/metabolic feature analysis and the other by a CNN, followed by a two-step classifier, one step being rule based and the other being based on support vector machines. Results: The authors evaluated the detection performance using 104 PET/CT images collected by a cancer-screening program. The sensitivity in detecting candidates at an initial stage was 97.2%, with 72.8 FPs/case. After performing the proposed FP-reduction method, the sensitivity of detection was 90.1%, with 4.9 FPs/case; the proposed method eliminated approximately half the FPs existing in the previous study. Conclusions: An improved FP-reduction scheme using CNN technique has been developed for the detection of pulmonary nodules in PET/CT images. The authors’ ensemble FP-reduction method eliminated 93% of the FPs; their proposed method using CNN technique eliminates approximately half the FPs existing in the previous study. These results indicate that their method may be useful in the computer-aided detection of pulmonary nodules

  4. Relapse of pulmonary tuberculosis: a rare cause of false-positive of the scintigraphy with iodine 131; Sequelles de tuberculose pulmonaire: une rare cause de faux-positif de la scintigraphie a l'iode 131

    Energy Technology Data Exchange (ETDEWEB)

    Ungureanu, C.M.; Angoue, O.; Blagosklonov, O.; Boulahdour, H. [Service de medecine nucleaire, CHU Jean-Minjoz, Besancon, (France); Manzoni, P. [service de radiologie, CHU Jean-Minjoz, Besancon, (France)

    2009-05-15

    The whole body scintigraphy with {sup 131}I is used in the follow up of the differentiated thyroid cancer. It is important to know the causes of false positive before decision of treatment by iodine 131. We present the case of a patient with a pulmonary fixation that was a false positive of {sup 131}I, of rare etiology. The after-effects of tuberculosis are able to fix iodine 131 and then to give false positive. scintigraphy. This etiology of false positive is rare and is worthy to be known because the lung is frequently an area of metastases in the thyroid cancer and the incidence of tuberculosis is increasing. (N.C.)

  5. Anticitrullinated protein/peptide antibody multiplexing defines an extended group of ACPA-positive rheumatoid arthritis patients with distinct genetic and environmental determinants.

    Science.gov (United States)

    Rönnelid, Johan; Hansson, Monika; Mathsson-Alm, Linda; Cornillet, Martin; Reed, Evan; Jakobsson, Per-Johan; Alfredsson, Lars; Holmdahl, Rikard; Skriner, Karl; Serre, Guy; Lundberg, Karin; Klareskog, Lars

    2018-02-01

    The second generation anticycliccitrullinated peptide (anti-CCP2) assay detects the majority but not all anticitrullinated protein/peptide antibodies (ACPA). Anti-CCP2-positive rheumatoid arthritis (RA) is associated with HLA-DRB1* shared epitope (SE) alleles and smoking. Using a multiplex assay to detect multiple specific ACPA, we have investigated the fine specificity of individual ACPA responses and the biological impact of additional ACPA reactivity among anti-CCP2-negative patients. We investigated 2825 patients with RA and 551 healthy controls with full data on anti-CCP2, HLA-DRB1* alleles and smoking history concerning reactivity against 16 citrullinated peptides and arginine control peptides with a multiplex array. The prevalence of the 16 ACPA specificities ranged from 9% to 58%. When reactivity to arginine peptides was subtracted, the mean diagnostic sensitivity increased by 3.2% with maintained 98% specificity. Of the anti-CCP2-negative patients, 16% were found to be ACPA positive. All ACPA specificities associated with SE, and all but one with smoking. Correction for arginine reactivity also conveyed a stronger association with SE for 13/16 peptides. Importantly, when all ACPA specificities were analysed together, SE and smoking associated with RA in synergy among ACPA positive, but not among ACPA-negative subjects also in the anti-CCP2-negative subset. Multiplexing detects an enlarged group of ACPA-positive but anti-CCP2-negative patients with genetic and environmental attributes previously assigned to anti-CCP2-positive patients. The individual correction for arginine peptide reactivity confers both higher diagnostic sensitivity and stronger association to SE than gross ACPA measurement. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  6. Zooming into the binding groove of HLA molecules : which positions and which substitutions change peptide binding most?

    NARCIS (Netherlands)

    van Deutekom, Hanneke W M; Kesmir, C.

    Human leukocyte antigen (HLA) genes are the most polymorphic genes in the human genome. Almost all polymorphic residues are located in the peptide-binding groove, resulting in different peptide-binding preferences. Whether a single amino acid change can alter the peptide-binding repertoire of an HLA

  7. 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

    Science.gov (United States)

    2011-01-20

    in the field the rate of false positives relative to the rate of true planets (false alarm rate, FAR) can be written quite generally as FAR = NFP /( NFP ...Np), where NFP is the number of false positives and Np is the number of planets in the sample. Thus, the larger the number of planets we expect, the...product of BF and the size of the sample or NFP = BF × 156,097 = 0.016. The number of small planets expected in the sample is of course not known, and

  8. A D-enantiomer of the antimicrobial peptide GL13K evades antimicrobial resistance in the Gram positive bacteria Enterococcus faecalis and Streptococcus gordonii.

    Science.gov (United States)

    Hirt, Helmut; Hall, Jeffrey W; Larson, Elliot; Gorr, Sven-Ulrik

    2018-01-01

    Antimicrobial peptides represent an alternative to traditional antibiotics that may be less susceptible to bacterial resistance mechanisms by directly attacking the bacterial cell membrane. However, bacteria have a variety of defense mechanisms that can prevent cationic antimicrobial peptides from reaching the cell membrane. The L- and D-enantiomers of the antimicrobial peptide GL13K were tested against the Gram-positive bacteria Enterococcus faecalis and Streptococcus gordonii to understand the role of bacterial proteases and cell wall modifications in bacterial resistance. GL13K was derived from the human salivary protein BPIFA2. Minimal inhibitory concentrations were determined by broth dilution and a serial assay used to determine bacterial resistance. Peptide degradation was determined in a bioassay utilizing a luminescent strain of Pseudomonas aeruginosa to detect peptide activity. Autolysis and D-alanylation-deficient strains of E. faecalis and S. gordonii were tested in autolysis assays and peptide activity assays. E. faecalis protease inactivated L-GL13K but not D-GL13K, whereas autolysis did not affect peptide activity. Indeed, the D-enantiomer appeared to kill the bacteria prior to initiation of autolysis. D-alanylation mutants were killed by L-GL13K whereas this modification did not affect killing by D-GL13K. The mutants regained resistance to L-GL13K whereas bacteria did not gain resistance to D-GL13K after repeated treatment with the peptides. D-alanylation affected the hydrophobicity of bacterial cells but hydrophobicity alone did not affect GL13K activity. D-GL13K evades two resistance mechanisms in Gram-positive bacteria without giving rise to substantial new resistance. D-GL13K exhibits attractive properties for further antibiotic development.

  9. Output Position and Word Relatedness Effects in a DRM Paradigm: Support for a Dual-Retrieval Process Theory of Free Recall and False Memories

    Science.gov (United States)

    Barnhardt, T. M.; Choi, H.; Gerkens, D. R.; Smith, S. M.

    2006-01-01

    Five experiments investigated predictions--derived from a dual-retrieval process approach to free recall (Brainerd, C. J., Wright, R., Reyna, V. F., & Payne, D. G. (2002). Dual-retrieval processes in free and associative recall. Journal of Memory and Language, 46, 120-152.)--about false memories in a DRM-like paradigm. In all the experiments, the…

  10. Abiotic production of nitrous oxide by lightning. Implications for a false positive identification of life on Earth-Like Planets around quiescent M Dwarfs

    Science.gov (United States)

    Navarro, Karina F.; Navarro-Gonzalez, Rafael; McKay, Christopher P.

    _{2} dominated primitive Earth-like atmospheres. However, during the rise in atmospheric O _{2} at the start of the Proterozoic, the ocean became stratified (anoxic at the bottom and oxygenic at the surface). During this period, the emissions of N _{2}O were probably higher than today associated with a stronger microbial activity in the early anoxic ocean layer (Grenfell et al., 2011). Under this scenario, the predicted N _{2}O concentration would be about 3920 ppb, considering 10% the current atmospheric O _{2} concentrations, 100 times higher the current microbial N _{2}O flux, and a fainter Sun (94.3%) (Grenfell et al., 2011). This concentration would be still undetectable (Grenfell et al., 2011). A completely different scenario could be expected in Earth-like planets orbiting M dwarfs, which are the most abundant stars in the galaxy, representing about 75% of the total stellar population. M stars exhibit a large range in activity levels from very low levels of chromospheric and coronal activity, the so-called “quiescent” to high levels, the so-called “active" states. Photochemical models predict that the N _{2}O concentration would only increase to about 1,000 ppb for the current Earth orbiting an active M star, but surprisingly up to about 1,000 ppm for the current Earth orbiting a quiescent M star (Segura et al., 2005). Therefore, N _{2}O becomes a promising biomarker. Under this scenario it is important to constrain the abiotic sources of N _{2}O under different atmospheric conditions to avoid a false positive identification of life. Here we report an experimental study of the effects of lightning discharges on the nitrogen fixation rate during the evolution of the Earth’s early atmosphere from 10 to 1 percent of carbon dioxide in molecular nitrogen. We extended our study from no methane up to 1,000 ppm CH _{4}, which would be applicable to the postbiotic Earth (Tian et al., 2011). Lightning was simulated in the laboratory by a plasma generated with a

  11. MARVELS-1: A FACE-ON DOUBLE-LINED BINARY STAR MASQUERADING AS A RESONANT PLANETARY SYSTEM AND CONSIDERATION OF RARE FALSE POSITIVES IN RADIAL VELOCITY PLANET SEARCHES

    International Nuclear Information System (INIS)

    Wright, Jason T.; Roy, Arpita; Mahadevan, Suvrath; Wang, Sharon X.; Fleming, Scott W.; Ford, Eric B.; Payne, Matt; Lee, Brian L.; Ge, Jian; Wang, Ji; Crepp, Justin R.; Gaudi, B. Scott; Eastman, Jason; Pepper, Joshua; Cargile, Phillip; Stassun, Keivan G.; Ghezzi, Luan; González-Hernández, Jonay I.; Wisniewski, John; Dutra-Ferreira, Leticia

    2013-01-01

    We have analyzed new and previously published radial velocity (RV) observations of MARVELS-1, known to have an ostensibly substellar companion in a ∼6 day orbit. We find significant (∼100 m s –1 ) residuals to the best-fit model for the companion, and these residuals are naïvely consistent with an interior giant planet with a P = 1.965 days in a nearly perfect 3:1 period commensurability (|P b /P c – 3| –4 ). We have performed several tests for the reality of such a companion, including a dynamical analysis, a search for photometric variability, and a hunt for contaminating stellar spectra. We find many reasons to be critical of a planetary interpretation, including the fact that most of the three-body dynamical solutions are unstable. We find no evidence for transits, and no evidence of stellar photometric variability. We have discovered two apparent companions to MARVELS-1 with adaptive optics imaging at Keck; both are M dwarfs, one is likely bound, and the other is likely a foreground object. We explore false-alarm scenarios inspired by various curiosities in the data. Ultimately, a line profile and bisector analysis lead us to conclude that the ∼100 m s –1 residuals are an artifact of spectral contamination from a stellar companion contributing ∼15%-30% of the optical light in the system. We conclude that origin of this contamination is the previously detected RV companion to MARVELS-1, which is not, as previously reported, a brown dwarf, but in fact a G dwarf in a face-on orbit.

  12. Differentiation of Boc-protected alpha,delta-/delta,alpha- and beta,delta-/delta,beta-hybrid peptide positional isomers by electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Raju, G; Ramesh, V; Srinivas, R; Sharma, G V M; Shoban Babu, B

    2010-06-01

    Two new series of Boc-N-alpha,delta-/delta,alpha- and beta,delta-/delta,beta-hybrid peptides containing repeats of L-Ala-delta(5)-Caa/delta(5)-Caa-L-Ala and beta(3)-Caa-delta(5)-Caa/delta(5)-Caa-beta(3)-Caa (L-Ala = L-alanine, Caa = C-linked carbo amino acid derived from D-xylose) have been differentiated by both positive and negative ion electrospray ionization (ESI) ion trap tandem mass spectrometry (MS/MS). MS(n) spectra of protonated isomeric peptides produce characteristic fragmentation involving the peptide backbone, the Boc-group, and the side chain. The dipeptide positional isomers are differentiated by the collision-induced dissociation (CID) of the protonated peptides. The loss of 2-methylprop-1-ene is more pronounced for Boc-NH-L-Ala-delta-Caa-OCH(3) (1), whereas it is totally absent for its positional isomer Boc-NH-delta-Caa-L-Ala-OCH(3) (7), instead it shows significant loss of t-butanol. On the other hand, second isomeric pair shows significant loss of t-butanol and loss of acetone for Boc-NH-delta-Caa-beta-Caa-OCH(3) (18), whereas these are insignificant for its positional isomer Boc-NH-beta-Caa-delta-Caa-OCH(3) (13). The tetra- and hexapeptide positional isomers also show significant differences in MS(2) and MS(3) CID spectra. It is observed that 'b' ions are abundant when oxazolone structures are formed through five-membered cyclic transition state and cyclization process for larger 'b' ions led to its insignificant abundance. However, b(1)(+) ion is formed in case of delta,alpha-dipeptide that may have a six-membered substituted piperidone ion structure. Furthermore, ESI negative ion MS/MS has also been found to be useful for differentiating these isomeric peptide acids. Thus, the results of MS/MS of pairs of di-, tetra-, and hexapeptide positional isomers provide peptide sequencing information and distinguish the positional isomers. Copyright 2010 John Wiley & Sons, Ltd.

  13. Heat treatment and false-positive heartworm antigen testing in ex vivo parasites and dogs naturally infected by Dirofilaria repens and Angiostrongylus vasorum

    Directory of Open Access Journals (Sweden)

    Luigi Venco

    2017-11-01

    Full Text Available Abstract Background 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 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

  14. Heat treatment and false-positive heartworm antigen testing in ex vivo parasites and dogs naturally infected by Dirofilaria repens and Angiostrongylus vasorum.

    Science.gov (United States)

    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

  15. Different percentages of false-positive results obtained using five methods for the calculation of reference change values based on simulated normal and ln-normal distributions of data

    DEFF Research Database (Denmark)

    Lund, Flemming; Petersen, Per Hyltoft; Fraser, Callum G

    2016-01-01

    a homeostatic set point that follows a normal (Gaussian) distribution. This set point (or baseline in steady-state) should be estimated from a set of previous samples, but, in practice, decisions based on reference change value are often based on only two consecutive results. The original reference change value......-positive results. The aim of this study was to investigate false-positive results using five different published methods for calculation of reference change value. METHODS: The five reference change value methods were examined using normally and ln-normally distributed simulated data. RESULTS: One method performed...... best in approaching the theoretical false-positive percentages on normally distributed data and another method performed best on ln-normally distributed data. The commonly used reference change value method based on two results (without use of estimated set point) performed worst both on normally...

  16. Differential binding to frequent HLA-A alleles of p21 RAS derived peptides bearing oncogenic substitutions at position 12 or 13.

    Science.gov (United States)

    Gouttefangeas, C; Demeur, C; Connan, F; Balayn, N; Choppin, J; Tilkin-Mariamé, A F

    1997-07-01

    RAS oncogenic proteins are frequently found mutated in human cancers, where they are known to be implicated in the tumoral process. Mutations occur preferentially at positions 12, 13 or 61. Identification of potential T cell epitopes is the first step to determine it RAS mutated proteins can generate tumor specific antigens which could be further used as targets for cancer immunotherapy protocols. We have investigated the capacity of synthetic wild-type and mutant RAS derived peptides encompassing positions 12 and 13 to bind to three frequent HLA-A alleles: HLA-A*0201, HLA-A*0301 and HLA-A*1101. Binding was evaluated by two methods using TAP-defective cell lines: a cytometric assay based on HLA molecules stabilization at the cell surface, and an assembly assay detecting interactions between solubilized HLA molecules and peptides. Positive HLA binding was observed for two sets of synthetic peptides, one specific for HLA-A*0201 allele (RAS 5-14), and the other one specific for HLA-A*0301 and HLA-A*1101 alleles (RAS 8-16). Interestingly, the different substitutions at positions 12 and 13 were not equivalent for HLA binding. These observations will be useful for the in vitro generation of restricted CD8+ T lymphocytes specific for mutated RAS proteins and recognizing tumoral cells expressing such RAS mutations.

  17. 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.

    Science.gov (United States)

    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.

  18. Patterns of Nucleotide Diversity at the Regions Encompassing the Drosophila Insulin-Like Peptide (dilp) Genes: Demography vs. Positive Selection in Drosophila melanogaster

    Science.gov (United States)

    Guirao-Rico, Sara; Aguadé, Montserrat

    2013-01-01

    In Drosophila, the insulin-signaling pathway controls some life history traits, such as fertility and lifespan, and it is considered to be the main metabolic pathway involved in establishing adult body size. Several observations concerning variation in body size in the Drosophila genus are suggestive of its adaptive character. Genes encoding proteins in this pathway are, therefore, good candidates to have experienced adaptive changes and to reveal the footprint of positive selection. The Drosophila insulin-like peptides (DILPs) are the ligands that trigger the insulin-signaling cascade. In Drosophila melanogaster, there are several peptides that are structurally similar to the single mammalian insulin peptide. The footprint of recent adaptive changes on nucleotide variation can be unveiled through the analysis of polymorphism and divergence. With this aim, we have surveyed nucleotide sequence variation at the dilp1-7 genes in a natural population of D. melanogaster. The comparison of polymorphism in D. melanogaster and divergence from D. simulans at different functional classes of the dilp genes provided no evidence of adaptive protein evolution after the split of the D. melanogaster and D. simulans lineages. However, our survey of polymorphism at the dilp gene regions of D. melanogaster has provided some evidence for the action of positive selection at or near these genes. The regions encompassing the dilp1-4 genes and the dilp6 gene stand out as likely affected by recent adaptive events. PMID:23308258

  19. 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

    Science.gov (United States)

    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.

  20. PH dependent adhesive peptides

    Science.gov (United States)

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  1. Interpretation of captopril renal scintigraphy: report of a bilateral false positive case; Interpretation de la scintigraphie renale avec prise de captopril: a propos d`un faux positif bilateral

    Energy Technology Data Exchange (ETDEWEB)

    Patrois, F.; Hignette, C.; Froissart, M.; Prigent, A. [Hopital Broussais, 75 - Paris (France)

    1995-12-31

    Captopril renography is a quite sensitive (70-80%) and a very specific (90-95%) test for the diagnosis of renovascular hypertension induced by renal artery stenosis. Contrasting to morphological techniques (arteriography, intravenous digital subtraction angiography, duplex sonography, angio-MRI), captopril renography can predict the cure or improvement of hypertension after revascularization. Therefore captopril renography will discriminate the renal artery stenosis causing renovascular hypertension from incidental stenosis concomitant with essential hypertension. The test conditions and interpretation present some pitfalls we thereby would discuss, providing a case of bilateral false positive result. (authors). 22 refs., 6 figs.

  2. A case of anti-cyclic citrullinated peptides antibody positive rheumatoid meningitis without arthritis at the onset of neurological symptoms.

    Science.gov (United States)

    Abe, Tetsuya; Mishima, Kazuhiko; Uchino, Akira; Sasaki, Atsushi; Tanahashi, Norio; Takao, Masaki

    2016-09-29

    We report an 84-year-old woman with rheumatoid meningitis. She developed weakness in her muscles and became cognitively impaired. However, physical examination revealed no evidence of rheumatoid arthritis. Levels of anti-cyclic citrullinated peptide antibodies were elevated. Brain magnetic resonance imaging (MRI) showed hyperintense lesions in the frontotemporoparietal subarachnoid space on fluid attenuated inversion recovery (FLAIR) images. Leptomeningeal enhancement was also evident on gadolinium-enhanced T1-weighted images. We suspected rheumatoid meningitis. A brain biopsy was performed and methylprednisolone pulse therapy was started. Subsequently, her symptoms and MRI findings rapidly improved.

  3. A feedback framework for protein inference with peptides identified from tandem mass spectra

    Directory of Open Access Journals (Sweden)

    Shi Jinhong

    2012-11-01

    Full Text Available Abstract Background Protein inference is an important computational step in proteomics. There exists a natural nest relationship between protein inference and peptide identification, but these two steps are usually performed separately in existing methods. We believe that both peptide identification and protein inference can be improved by exploring such nest relationship. Results In this study, a feedback framework is proposed to process peptide identification reports from search engines, and an iterative method is implemented to exemplify the processing of Sequest peptide identification reports according to the framework. The iterative method is verified on two datasets with known validity of proteins and peptides, and compared with ProteinProphet and PeptideProphet. The results have shown that not only can the iterative method infer more true positive and less false positive proteins than ProteinProphet, but also identify more true positive and less false positive peptides than PeptideProphet. Conclusions The proposed iterative method implemented according to the feedback framework can unify and improve the results of peptide identification and protein inference.

  4. The potent antimicrobial properties of cell penetrating peptide-conjugated silver nanoparticles with excellent selectivity for Gram-positive bacteria over erythrocytes

    Science.gov (United States)

    Liu, Lihong; Yang, Jun; Xie, Jianping; Luo, Zhentao; Jiang, Jiang; Yang, Yi Yan; Liu, Shaomin

    2013-04-01

    Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (Gram-positive Bacillus subtilis, Gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects.Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (Gram-positive Bacillus subtilis, Gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34254a

  5. False-positive uptake on 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography/computed tomography (PET/CT) in oncological imaging

    International Nuclear Information System (INIS)

    Culverwell, A.D.; Scarsbrook, A.F.; Chowdhury, F.U.

    2011-01-01

    With the increasing utilization of integrated positron-emission tomography/computed tomography (PET/CT) using the glucose analogue 2-[ 18 F]-fluoro-2-deoxy-D-glucose (FDG) in oncological imaging, it is important for radiologists and nuclear medicine physicians to be aware that FDG uptake is not specific for malignancy, as many different physiological variants and benign pathological conditions can also exhibit increased glucose metabolism. Such false-positive FDG uptake often arises outside the area of primary interest and may mimic malignant disease, thereby confounding accurate interpretation of PET/CT studies. With the use of illustrative clinical cases, this article will provide a systematic overview of potential interpretative pitfalls and illustrate how such unexpected findings can be appropriately evaluated.

  6. Combinatorial Labeling Method for Improving Peptide Fragmentation in Mass Spectrometry

    Science.gov (United States)

    Kuchibhotla, Bhanuramanand; Kola, Sankara Rao; Medicherla, Jagannadham V.; Cherukuvada, Swamy V.; Dhople, Vishnu M.; Nalam, Madhusudhana Rao

    2017-06-01

    Annotation of peptide sequence from tandem mass spectra constitutes the central step of mass spectrometry-based proteomics. Peptide mass spectra are obtained upon gas-phase fragmentation. Identification of the protein from a set of experimental peptide spectral matches is usually referred as protein inference. Occurrence and intensity of these fragment ions in the MS/MS spectra are dependent on many factors such as amino acid composition, peptide basicity, activation mode, protease, etc. Particularly, chemical derivatizations of peptides were known to alter their fragmentation. In this study, the influence of acetylation, guanidinylation, and their combination on peptide fragmentation was assessed initially on a lipase (LipA) from Bacillus subtilis followed by a bovine six protein mix digest. The dual modification resulted in improved fragment ion occurrence and intensity changes, and this resulted in the equivalent representation of b- and y-type fragment ions in an ion trap MS/MS spectrum. The improved representation has allowed us to accurately annotate the peptide sequences de novo. Dual labeling has significantly reduced the false positive protein identifications in standard bovine six peptide digest. Our study suggests that the combinatorial labeling of peptides is a useful method to validate protein identifications for high confidence protein inference. [Figure not available: see fulltext.

  7. Estimating probabilities of peptide database identifications to LC-FTICR-MS observations

    Directory of Open Access Journals (Sweden)

    Daly Don S

    2006-02-01

    Full Text Available Abstract Background The field of proteomics involves the characterization of the peptides and proteins expressed in a cell under specific conditions. Proteomics has made rapid advances in recent years following the sequencing of the genomes of an increasing number of organisms. A prominent technology for high throughput proteomics analysis is the use of liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR-MS. Meaningful biological conclusions can best be made when the peptide identities returned by this technique are accompanied by measures of accuracy and confidence. Methods After a tryptically digested protein mixture is analyzed by LC-FTICR-MS, the observed masses and normalized elution times of the detected features are statistically matched to the theoretical masses and elution times of known peptides listed in a large database. The probability of matching is estimated for each peptide in the reference database using statistical classification methods assuming bivariate Gaussian probability distributions on the uncertainties in the masses and the normalized elution times. Results A database of 69,220 features from 32 LC-FTICR-MS analyses of a tryptically digested bovine serum albumin (BSA sample was matched to a database populated with 97% false positive peptides. The percentage of high confidence identifications was found to be consistent with other database search procedures. BSA database peptides were identified with high confidence on average in 14.1 of the 32 analyses. False positives were identified on average in just 2.7 analyses. Conclusion Using a priori probabilities that contrast peptides from expected and unexpected proteins was shown to perform better in identifying target peptides than using equally likely a priori probabilities. This is because a large percentage of the target peptides were similar to unexpected peptides which were included to be false positives. The use of

  8. O7.10CORRELATION OF PRE-OPERATIVE LANGUAGE FMRI WITH INTRA-OPERATIVE DIRECT CORTICAL STIMULATION FINDINGS IN GLIOMA SURGERY IDENTIFIES POTENTIAL FALSE POSITIVE FMRI ACTIVATIONS WITH CONVENTIONAL ANALYSIS

    Science.gov (United States)

    Coope, D.J.; Karabatsou, K.; Green, S.; Wall, G.; Bambrough, J.

    2014-01-01

    BACKGROUND: Functional MRI (fMRI) has an increasingly established role in surgical planning for glioma patients. However, the presence of neuro-vascular decoupling in the vicinity of the tumor, along with other tumor specific phenomena, raises at least theoretical concerns of potential inaccuracies. Several studies have attempted to correlate fMRI findings with cortical mapping performed using direct cortical stimulation (DCS). Results with respect to language mapping in particular have not been consistent and have focused upon investigating the sensitivity of fMRI to detect eloquent tissue. The possibility of false positive activations that could lead to regions of tumor being incorrectly labeled as inoperable has not been fully explored, in part due to the challenge of accurately recording DCS findings. METHODS: Ten patients with suspected primary or recurrent low-grade gliomas underwent pre-operative fMRI including 3-4 language paradigms on a Phillips 3T Achieva scanner. Comprehensive neuropsychological assessment was also completed prior to awake craniotomy. fMRI data processed using Phillips proprietary IViewBOLD was made available using the BrainLab VectorVision neuro-navigation system for planning of the craniotomy. The surgeon was blinded to fMRI outcomes for the duration of cortical mapping to minimize bias. DCS was completed using a bipolar stimulator tracked continuously using the BrainLab system networked via the VVLink interface to a research system running 3D Slicer. DCS outcomes were recorded by the surgeon using a panel of footswitches to trigger a custom logging module. fMRI data was re-processed using Statistical Parametric Mapping (SPM) 8 to generate t-statistic maps with a simple threshold of 3 applied analogous to the standard clinical implementation. DCS outcomes within 10mm of a cluster of ≥10 voxels above the threshold were analyzed. RESULTS: A mean of 125.4 [range 64-178] unique DCS outcomes were recorded per subject with 60 [32

  9. ImmunoCAP cellulose displays cross-reactive carbohydrate determinant (CCD) epitopes and can cause false-positive test results in patients with high anti-CCD IgE antibody levels.

    Science.gov (United States)

    Hemmer, Wolfgang; Altmann, Friedrich; Holzweber, Friedrich; Gruber, Clemens; Wantke, Felix; Wöhrl, Stefan

    2018-01-01

    sufficient to cause false-positive test results up to 2 kU A /L with nonglycosylated recombinant allergens in patients with high levels of anti-CCD IgE antibodies. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  10. Differentiation of Positional Isomers of Hybrid Peptides Containing Repeats of β-Nucleoside Derived Amino Acid (β-Nda-) and L-Amino Acids by Positive and Negative Ion Electrospray Ionization Tandem Mass Spectrometry (ESI-MS n )

    Science.gov (United States)

    Raju, B.; Ramesh, M.; Srinivas, R.; Chandrasekhar, S.; Kiranmai, N.; Sarma, V. U. M.

    2011-04-01

    A new class of positional isomeric pairs of -Boc protected oligopeptides comprised of alternating nucleoside derived β-amino acid (β-Nda-) and L-amino acid residues (alanine, valine, and phenylalanine) have been differentiated by both positive and negative ion electrospray ionization ion-trap tandem mass spectrometry (ESI-MS n ). The protonated dipeptide positional isomers with β-Nda- at the N-terminus lose CH3OH, NH3, and C2H4O2, whereas these processes are absent for the peptides with L-amino acids at the N-terminus. Instead, the presence of L-amino acids at the N-terminus results in characteristic retro-Mannich reaction involving elimination of imine. A good correlation has been observed between the conformational structure of the peptides and the abundance of y{n/+} and b{n/+} ions in MS n spectra. In the case of tetrapeptide isomers that are reported to form helical structures in solution phase, no y{n/+} and b{n/+} ions are observed when the corresponding amide -NH- participates in the helical structures. In contrast, significant y{n/+} and b{n/+} ions are formed when the amide -NH- is not involved in the H-bonding. In the case of tetra- and hexapeptides, it is observed that abundant b{n/+} ions are formed, presumably with stable oxazolone structures when the C-terminus of the b{n/+} ions possessed L-amino acid and the β-Nda- at the C-terminus appears to prevent the cyclization process leading to the absence of corresponding b{n/+} ions.

  11. Synaptotagmin-7 as a positive regulator of glucose-induced glucagon-like peptide-1 secretion in mice

    DEFF Research Database (Denmark)

    Gustavsson, N; Wang, Y; Kang, Y

    2011-01-01

    using synaptotagmin-7 knockout (KO) mice and GLUTag cells with lentiviral-mediated synaptotagmin-7 silencing. RESULTS: We found that synaptotagmin-7 was co-localised with GLP-1 in intestinal L-cells. GLP-1 secretion was impaired in synaptotagmin-7 KO mice when they were challenged by glucose ingestion...... that synaptotagmin-7 functions as a positive regulator of GLP-1 secretion in intestinal L-cells and GLUTag cells, consistent with its proposed role as a calcium sensor in GLP-1 secretion....

  12. Baryogenesis in false vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Yuta [KEK Theory Center, IPNS, KEK, Tsukuba, Ibaraki (Japan); Yamada, Masatoshi [Kanazawa University, Institute for Theoretical Physics, Kanazawa (Japan)

    2017-09-15

    The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales, such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators. (orig.)

  13. Metabolitos del efavirenz como probable causa de falsos-positivos en test inmunológico para benzodiacepinas en orina False-positive immunoassay results for urine benzodiacepines probably caused by efavirenz metabolites

    Directory of Open Access Journals (Sweden)

    Patricia N. Quiroga

    2007-12-01

    Full Text Available En el tratamiento del síndrome de inmunodeficiencia adquirida (SIDA una de las drogas antirretrovirales usadas es el efavirenz (EFV. Existe una asociación entre el consumo de drogas de abuso y la probabilidad de adquirir el SIDA, razón por la cual se solicita su investigación en orina. Como método de screening para detectar el consumo de estas drogas se utilizan habitualmente los ensayos inmunológicos. Una característica especial de estos métodos son las reacciones cruzadas que pueden presentarse con sustancias estructuralmente relacionadas dando origen a resultados falsos positivos. Al analizar 18 muestras de orina de pacientes con SIDA, se observó un 78% de resultados falsos positivos para benzodiacepinas (BZD cuando fueron analizados mediante el ensayo inmunológico Triage® (Ascend Multi Immune Assay. El estudio confirmatorio por cromatografía gaseosa acoplada a espectrometría de masa (GC-MS reveló la ausencia de BZD en todos los casos y el 100% de los resultados falsos positivos observados correspondieron a las muestras de los pacientes tratados con EFV. Con el propósito de dilucidar el origen de esta reacción cruzada fueron aislados el EFV y sus metabolitos de las muestras de orina, mediante extracción en fase sólida (SPE y cromatografía en capa delgada de alta resolución (HPTLC, e identificados por cromatografía gaseosa- espectrometría de masa (GC-MS y GC-MS/MS/MS. Los resultados obtenidos en este estudio indicarían que los metabolitos del EFV (8-OH-EFV y/o 7-OH-EFV y no el EFV podrían ser los responsables de la reacción cruzada observada en el ensayo inmunológico.Efavirenz (EFV is an antiretroviral drug used in the acquired immunodeficiency syndrome (AIDS treatment. Immunoassay techniques have been widely used for abuse drug screening test. The presence of structurally related substances in urine samples can interfere by cross reactions causing false positive results. High percentage of false positive results (78

  14. Nanoparticle Mediated Drug Delivery of Rolipram to Tyrosine Kinase B Positive Cells in the Inner Ear with Targeting Peptides and Agonistic Antibodies

    Directory of Open Access Journals (Sweden)

    Rudolf eGlueckert

    2015-05-01

    Full Text Available AimSystemic pharmacotherapies have limitation due to blood-labyrinth barrier, so local delivery via the round window membrane opens a path for effective treatment. Multifunctional nanoparticle (NP mediated cell specific drug delivery may enhance efficacy and reduce side effects. Different NPs with ligands to target TrkB receptor were tested. Distribution, uptake mechanisms, trafficking, and bioefficacy of drug release of rolipram loaded NPs were evaluated.Methods We tested lipid based nanocapsules (LNCs, Quantum Dot, silica NPs with surface modification by peptides mimicking TrkB or TrkB activating antibodies. Bioefficacy of drug release was tested with rolipram loaded LNCs to prevent cisplatin induced apoptosis. We established different cell culture models with SH-SY-5Y and inner ear derived cell lines and used neonatal and adult mouse explants. Uptake and trafficking was evaluated with FACS and confocal as well as transmission electron microscopy. ResultsPlain NPs show some selectivity in uptake related to the in-vitro system properties, carrier material and NP size. Some peptide ligands provide enhanced targeted uptake to neuronal cells but failed to show this in cell cultures. Agonistic antibodies linked to silica NPs showed TrkB activation and enhanced binding to inner ear derived cells. Rolipram loaded LNCs proved as effective carriers to prevent cisplatin induced apoptosis.DiscussionMost NPs with targeting ligands showed limited effects to enhance uptake. NP aggregation and unspecific binding may change uptake mechanisms and impair endocytosis by an overload of NPs. This may affect survival signaling. NPs with antibodies activate survival signaling and show effective binding to TrkB positive cells but needs further optimization for specific internalization. Bioefficiacy of rolipram release confirms LNCs as encouraging vectors for drug delivery of lipophilic agents to the inner ear with ideal release characteristics independent of

  15. Introduction of a cis-prolyl mimic in position 7 of the peptide hormone oxytocin does not result in antagonistic activity.

    Science.gov (United States)

    Wittelsberger, Angela; Patiny, Luc; Slaninova, Jirina; Barberis, Claude; Mutter, Manfred

    2005-10-20

    New insights into the structure-activity relationship of the peptide hormone oxytocin are presented. Incorporation of the novel cis-prolyl mimic 2,2-dimethyl-1,3-thiazolidine-4-carboxylic acid (pseudoproline, PsiPro) at position 7 of the hormone yielded the analogue [Cys(Psi(Me,Me)pro)]7oxytocin (1) that showed a 92-95% induction of the cis peptide bond conformation between Cys6 and PsiPro7, as determined by one- and two-dimensional NMR spectra in water and in DMSO-d6. The impact of the dimethyl moiety regarding conformation and bioactivity was investigated by the synthesis of the corresponding dihydro compound, [Cys(Psi(H,H)pro)]7oxytocin (2). Biological tests of the uterotonic activity, the pressor activity, and the binding affinity to the rat and human oxytocin receptors were carried out. As a most significant result, no antagonistic activities were found for both the cis-constrained analogue 1 and analogue 2, suggesting that a cis conformation between residues 6 and 7 of the molecule does not result in antagonistic activity. However, the about 10-fold reduction in agonistic activity of 1 as compared to oxytocin is consistent with the reduction of the trans conformation from 90% for oxytocin to 5-8% for compound 1. Compound 1 retained a high binding affinity for the oxytocin receptor, with K(i) values of 8.0 and 1.9 nM for the rat and the human receptor, respectively. The correlation between the biological activities and the cis contents obtained from NMR analysis for compounds 1, 2, and oxytocin leads to the hypothesis that a cis/trans conformational change plays an important role in oxytocin receptor binding and activation.

  16. Comorbidities in Anti-Cyclic Citrullinated Peptide Positive At-Risk Individuals Do Not Differ from Those Patients with Early Inflammatory Arthritis.

    Science.gov (United States)

    Twigg, Sarah; Nikiphorou, Elena; Nam, Jackie L; Hunt, Laura; Mankia, Kulveer; Pentony, Peta Elizabeth; Freeston, Jane E; Tan, Ai Lyn; Emery, Paul

    2018-01-01

    To compare comorbidities in a cohort of cyclic citrullinated peptide (CCP) antibody positive patients without or prior to onset of inflammatory arthritis (IA) to those in patients with early IA. Baseline data from two established cohorts were used. The first recruited people at risk of IA: CCP antibody positive cases without IA (CCP Cohort, n  = 296). The second cohort [the Inflammatory Arthritis CONtinuum study (IACON)] recruited patients with early IA ( n  = 725). Proportions of patients with given comorbidities were compared between cohorts and then logistic regression was used to determine odds ratios (OR) for the CCP cohort having specific comorbidities, compared to IACON patients. Analyses adjusted for gender, age, smoking status, and body mass index. Patients from the CCP cohort were younger (mean age 50, compared to 53 years). The proportion of patients with at least one comorbidity was higher in the IACON than the CCP cohort: (40% compared to 24%, respectively). Results of logistic regression analyses suggested the odds of hypertension, taking a lipid-lowering agent, ischemic heart disease, cerebrovascular disease, lung disease, and diabetes were not increased in either cohort. However, patients in the CCP cohort were more likely to be taking an antidepressant (OR = 1.62, 95% CI 1.03, 2.56, p  = 0.037). There was no significant difference in comorbidities among people with CCP antibodies but without IA, compared to those of patients with established IA.

  17. Functional synergy of α-helical antimicrobial peptides and traditional antibiotics against Gram-negative and Gram-positive bacteria in vitro and in vivo.

    Science.gov (United States)

    Feng, Q; Huang, Y; Chen, M; Li, G; Chen, Y

    2015-01-01

    In this study, the antimicrobial activities based on the synergistic effects of traditional antibiotics (imipenem, cefepime, levofloxacin hydrochloride and vancomycin) and antimicrobial peptides (AMPs; PL-5, PL-31, PL-32, PL-18, PL-29 and PL-26), alone or in combination, against three Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae and Staphylococcus epidermidis) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) were investigated. In addition, the antimicrobial activity that was based on the synergistic effects of levofloxacin hydrochloride and PL-5 against Staphylococcus aureus in vivo was explored in a mouse infection model. Traditional antibiotics and AMPs showed significant synergistic effects on the antibacterial activities against the different Gram-positive and Gram-negative bacteria in vitro. A strong synergistic effect in the PL-5 and levofloxacin hydrochloride combination against Staphylococcus aureus was observed in the mouse infection model in vivo. The mechanism of synergistic action was due to the different targets of AMPs and traditional antibiotics. The combination of AMPs and traditional antibiotics can dramatically enhance antimicrobial activity and may help prevent or delay the emergence of antibiotic resistance. Thus, this combination therapy could be a promising approach to treat bacterial infections, particularly mixed infections and multi-antibiotic-resistant infections, in the clinics.

  18. Somatostatin, substance P and calcitonin gene-related peptide-positive intramural nerve structures of the human large intestine affected by carcinoma.

    Directory of Open Access Journals (Sweden)

    Jerzy Kaleczyc

    2010-11-01

    Full Text Available The aim of this study was to investigate the arrangement and chemical coding of enteric nerve structures in the human large intestine affected by cancer. Tissue samples comprising all layers of the intestinal wall were collected during surgery form both morphologically unchanged and pathologically altered segments of the intestine (n=15, and fixed by immersion in buffered paraformaldehyde solution. The cryostat sections were processed for double-labelling immunofluorescence to study the distribution of the intramural nerve structures (visualized with antibodies against protein gene-product 9.5 and their chemical coding using antibodies against somatostatin (SOM, substance P (SP and calcitonin gene-related peptide (CGRP. The microscopic observations revealed distinct morphological differences in the enteric nerve system structure between the region adjacent to the cancer invaded area and the intact part of the intestine. In general, infiltration of the cancer tissue resulted in the gradual (depending on the grade of invasion first decomposition and reduction to final partial or complete destruction and absence of the neuronal elements. A comparative analysis of immunohistochemically labeled sections (from the unchanged and pathologically altered areas revealed a statistically significant decrease in the number of CGRP-positive neurons and nerve fibres in both submucous and myenteric plexuses in the transitional zone between morphologically unchanged and cancer-invaded areas. In this zone, a decrease was also observed in the density of SP-positive nerve fibres in all intramural plexuses. Conversely, the investigations demonstrated statistically insignificant differences in number of SP- and SOM-positive neurons and a similar density of SOM-positive nerve fibres in the plexuses of the intact and pathologically changed areas. The differentiation between the potential adaptive changes in ENS or destruction of its elements by cancer invasion should be

  19. Diversity-oriented peptide stapling

    DEFF Research Database (Denmark)

    Tran, Thu Phuong; Larsen, Christian Ørnbøl; Røndbjerg, Tobias

    2017-01-01

    The introduction of macrocyclic constraints in peptides (peptide stapling) is an important tool within peptide medicinal chemistry for stabilising and pre-organising peptides in a desired conformation. In recent years, the copper-catalysed azide-alkyne cycloaddition (CuAAC) has emerged as a power......The introduction of macrocyclic constraints in peptides (peptide stapling) is an important tool within peptide medicinal chemistry for stabilising and pre-organising peptides in a desired conformation. In recent years, the copper-catalysed azide-alkyne cycloaddition (CuAAC) has emerged...... incorporating two azide-modified amino acids with 1,3,5-triethynylbenzene efficiently provides (i, i+7)- and (i, i+9)-stapled peptides with a single free alkyne positioned on the staple, that can be further conjugated or dimerised. A unique feature of the present method is that it provides easy access...

  20. O método da falsa posição na história e na educação matemática The false position method in history and in mathematics education

    Directory of Open Access Journals (Sweden)

    Cleide Farias de Medeiros

    2004-12-01

    Full Text Available Este texto coloca em uma perspectiva histórica o tratamento algébrico precoce que, costumeiramente, é dedicado ao ensino elementar da Aritmética. Defendendo que um tal tratamento algébrico precoce carrega vários pontos negativos para a formação do educando, o texto discute o "método da falsa posição" como uma alternativa viável para um tal ensino introdutório. Apontando as raízes históricas de tal método, o texto procura evidenciar as origens, aplicações e várias formas de visualizar este procedimento iterativo, desde a manipulação de materiais concretos, passando por aplicações geométricas, até atingir o Cálculo Numérico, como um dos procedimentos iterativos na resolução de equações lineares. Uma das conclusões é que, embora não seja o referido método, em sua forma mais simples, nenhum substitutivo para a resolução algébrica simbólica e moderna de equações e de sistemas de equações, ele se constitui certamente em um precioso trampolim para iniciarmos o salto em direção a um estudo mais formalizado. Particularmente, o método da falsa posição revela-se uma utilíssima ferramenta pedagógica na Educação Matemática, principalmente quando vinculado às suas origens históricas, suas abordagens concretas iniciais e suas associações com a Geometria e a Geometria Analítica.This text is a historical perspective on the early algebraic approach that is usually applied to the elementary teaching of Arithmetic. By arguing that such an initial algebraic treatment contains several drawbacks for elementary education, the ‘false position method' is discussed and is presented as a viable alternative for such introductory teaching. By pointing out the historical roots of the method, the text tries to make clear several ways of visualising this iterative procedure. This is done by incorporating the use of manipulatives and geometrical applications as well as the use of numerical calculus as an iterative

  1. False positive reaction due to endogenous biotin activity in glandular epithelium of decidua Reação falso positiva em epitélio glandular da decídua devido a atividade endógena de biotina

    Directory of Open Access Journals (Sweden)

    Liliana Cruz Spano

    2005-06-01

    Full Text Available Biotin-labeled probe was used in an in situ hybridisation assay to localize virus infection in formalin-fixed, paraffin embedded tissues taken from eleven abortion cases. Probes for human cytomegalovirus (HCMV, human Parvovirus B19 (B19 and human adenovirus type 2 (HAd2, were labeled with biotin-11-dUTP by nick-translation reaction. Streptavidin-alkaline-phosphatase (SAP was used to detect biotin, followed by 4-nitroblue tetrazolium/5-bromo-4-chloro-3-indolyl phosphate (NBT/BCIP solution. Positive reaction was observed in nucleus of glandular ephitelium cells of decidua either in positive or in negative control at first and second gestational trimester. The reaction was not inhibited with blocking solution for alkaline phosphatase endogenous activity and it persisted even with probes omission. The use of adequate negative control permitted to reveal the presence of nuclear biotin in glandular epithelium of decidua, responsible for false positivity in detection systems involving streptavidin biotin system (StrepABC. The stained cells resembled to cytophatic effect due to herpesvirus, which could induce further misinterpretation. The results obtained in this study strongly recommend that DNA detection by in situ hybridisation reaction in gestational endometrium should be done without using StrepABC system.Sondas marcadas com biotina foram utilizadas neste trabalho para detecção de infecção viral por hibridização in situ em tecidos fixados com formalina e embebidos em parafina de 11 casos obtidos de abortamento. Sondas para citomegalovírus humano (HCMV, parvovírus B19 humano (B19 e adenovírus humano tipo 2 (HAd2, foram marcadas com biotina-11-dUTP através da reação de nick-translation. Estreptavidina conjugada com fosfatase alcalina (SAP seguida por solução de 4-nitro-azul de tetrazolio/5-bromo-4-cloro-3-indolil fosfato (NBT/BCIP foram utilizadas para detecção da biotina após a reação de hibridização. Reação positiva foi

  2. Peptide dendrimers

    Czech Academy of Sciences Publication Activity Database

    Niederhafner, Petr; Šebestík, Jaroslav; Ježek, Jan

    2005-01-01

    Roč. 11, - (2005), 757-788 ISSN 1075-2617 R&D Projects: GA ČR(CZ) GA203/03/1362 Institutional research plan: CEZ:AV0Z40550506 Keywords : multiple antigen peptides * peptide dendrimers * synthetic vaccine * multipleantigenic peptides Subject RIV: CC - Organic Chemistry Impact factor: 1.803, year: 2005

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

    Science.gov (United States)

    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.

  4. False memories for aggressive acts.

    Science.gov (United States)

    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.

  5. Full-length insulin analogues and the effect of N-methylation of peptide bonds at positions B24, B25, B26

    Czech Academy of Sciences Publication Activity Database

    Antolíková, Emília; Žáková, Lenka; Cooper, A.; Kraus, Tomáš; Jiráček, Jiří

    2009-01-01

    Roč. 92, č. 4 (2009), s. 328-328 ISSN 0006-3525. [American Peptide Symposium /21./. 07.06.2009-12.06.2009, Bloomington] Institutional research plan: CEZ:AV0Z40550506 Keywords : ITC * N-methylation * dimerization Subject RIV: CC - Organic Chemistry

  6. Sleep deprivation and false memories.

    Science.gov (United States)

    Frenda, Steven J; Patihis, Lawrence; Loftus, Elizabeth F; Lewis, Holly C; Fenn, Kimberly M

    2014-09-01

    Many studies have investigated factors that affect susceptibility to false memories. However, few have investigated the role of sleep deprivation in the formation of false memories, despite overwhelming evidence that sleep deprivation impairs cognitive function. We examined the relationship between self-reported sleep duration and false memories and the effect of 24 hr of total sleep deprivation on susceptibility to false memories. We found that under certain conditions, sleep deprivation can increase the risk of developing false memories. Specifically, sleep deprivation increased false memories in a misinformation task when participants were sleep deprived during event encoding, but did not have a significant effect when the deprivation occurred after event encoding. These experiments are the first to investigate the effect of sleep deprivation on susceptibility to false memories, which can have dire consequences. © The Author(s) 2014.

  7. Cartilage oligomeric matrix protein associates differentially with erosions and synovitis and has a different temporal course in cyclic citrullinated peptide antibody (anti-CCP)-positive versus anti-CCP-negative early rheumatoid arthritis

    DEFF Research Database (Denmark)

    Christensen, Anne F; Lindegaard, Hanne; Hørslev-Petersen, Kim

    2011-01-01

    . We aimed to compare circulating cartilage oligomeric matrix protein (COMP), a marker of cartilage turnover, in untreated anti-CCP-positive and anti-CCP-negative RA, and to study the temporal pattern of COMP through 4 years of treatment, including the relationship to imaging and clinical findings.......Cyclic citrullinated peptide antibody (anti-CCP)-positive and anti-CCP-negative rheumatoid arthritis (RA) have been suggested as 2 distinctive disease subsets with respect to disease activity and prognosis. Previously, we proposed that anti-CCP antibodies might have a chondrocyte-suppressive effect...

  8. Prediction of lipoprotein signal peptides in Gram-negative bacteria

    DEFF Research Database (Denmark)

    Juncker, Agnieszka; Willenbrock, Hanni; Von Heijne, G.

    2003-01-01

    A method to predict lipoprotein signal peptides in Gram-negative Eubacteria, LipoP, has been developed. The hidden Markov model (HMM) was able to distinguish between lipoproteins (SPaseII-cleaved proteins), SPaseI-cleaved proteins, cytoplasmic proteins, and transmembrane proteins. This predictor...... was able to predict 96.8% of the lipoproteins correctly with only 0.3% false positives in a set of SPaseI-cleaved, cytoplasmic, and transmembrane proteins. The results obtained were significantly better than those of previously developed methods. Even though Gram-positive lipoprotein signal peptides differ...... from Gram-negatives, the HMM was able to identify 92.9% of the lipoproteins included in a Gram-positive test set. A genome search was carried out for 12 Gram-negative genomes and one Gram-positive genome. The results for Escherichia coli K12 were compared with new experimental data, and the predictions...

  9. Does Nasal Cocolonization by Methicillin-Resistant Coagulase-Negative Staphylococci and Methicillin-Susceptible Staphylococcus aureus Strains Occur Frequently Enough To Represent a Risk of False-Positive Methicillin-Resistant S. aureus Determinations by Molecular Methods?

    Science.gov (United States)

    Becker, Karsten; Pagnier, Isabelle; Schuhen, Brigitte; Wenzelburger, Frauke; Friedrich, Alexander W.; Kipp, Frank; Peters, Georg; von Eiff, Christof

    2006-01-01

    By analyzing the colonization of the anterior nares in cardiothoracic surgery patients on admission, nasal cocolonization by methicillin-susceptible Staphylococcus aureus and methicillin-resistant coagulase-negative staphylococci was detected in 8/235 (3.4%) specimens. Consequently, in a low-methicillin-resistant S. aureus (MRSA) setting, a molecular MRSA screening test targeting the mecA gene and an S. aureus-specific gene in parallel and applied directly to clinical specimens would be associated with an unacceptable positive predictive value of about 40%. PMID:16390977

  10. Preclinical pharmacokinetic, biodistribution, imaging and therapeutic efficacy of 177Lu-Labeled glycated bombesin analogue for gastrin-releasing peptide receptor-positive prostate tumor targeting

    International Nuclear Information System (INIS)

    Lim, Jae Cheong; Cho, Eun Ha; Kim, Jin Joo; Choi, Sang Mu; Lee, So Young; Nam, Sung Soo; Park, Ul Jae; Park, Soo Hyun

    2015-01-01

    The gastrin-releasing peptide receptor (GRPR) has been shown to be overexpressed in many human tumors, including prostate, colon, gastric, breast, pancreatic, and small cell lung cancers. Because bombesin (BBS) binds to GRPR with high affinity, BBS derivatives have been labeled with various radionuclides and have been demonstrated to be successful candidates for peptide receptor radiotherapy (PRRT). The present study describes the in vitro and in vivo preclinical characteristics of 177 Lu-DOTA-Lys(glucose)-4 aminobenzoic acid-BBS 7-14 ( 177 Lu-DOTA-gluBBN) to prepare radiolabeled candidates for the treatment of GRPR-expressing prostate tumors. Methods: 177 Lu-DOTA-gluBBN was prepared as previously published [1]. Human prostate PC-3 tumor cells were used to determine the binding (Kd) retention and efflux of 177 Lu-DOTA-gluBBN. Pharmacokinetic, imaging, and radiotherapy studies were performed in PC-3 xenografted mice. Results: The Kd value of 177 Lu-DOTA-gluBBN was 0.63 nM, with a maximum binding capacity (Bmax) of 669.7 fmol/10 6 cells (4.04 × 10 5 GRPR/cell). During a 2-hr incubation, 90.1 ± 0.4% of the cell-associated radio-peptide was internalized, and 56.3 ± 7.1% of the internalized radio-peptide was externalized in vitro. High amounts of the radio-peptide were rapidly accumulated in a PC-3 tumor in vivo, and the % ID/g of the tumor was 12.42 ± 2.15 1 hr p.i. The radio-peptide was quickly cleared from the blood, yielding tumor-to-blood ratios of 39.22 ± 17.36 at 1 hr p.i. and 330.67 ± 131.23 at 24 hr p.i. In addition, 177 Lu-DOTA-gluBBN was clearly visualized in PC-3 tumors 1 hr p.i. and significantly inhibited the tumor growth (P < 0.05). Treatment-related toxicity in the pancreas and kidneys was not observed, except for slight glomerulopathy. Conclusions: The pharmacokinetic, imaging, and therapy studies suggest that this 177 Lu-DOTA-gluBBN has promising characteristics for application in nuclear medicine, namely, for the diagnosis and treatment of GRPR

  11. Integrated Proteomic Pipeline Using Multiple Search Engines for a Proteogenomic Study with a Controlled Protein False Discovery Rate.

    Science.gov (United States)

    Park, Gun Wook; Hwang, Heeyoun; Kim, Kwang Hoe; Lee, Ju Yeon; Lee, Hyun Kyoung; Park, Ji Yeong; Ji, Eun Sun; Park, Sung-Kyu Robin; Yates, John R; Kwon, Kyung-Hoon; Park, Young Mok; Lee, Hyoung-Joo; Paik, Young-Ki; Kim, Jin Young; Yoo, Jong Shin

    2016-11-04

    In the Chromosome-Centric Human Proteome Project (C-HPP), false-positive identification by peptide spectrum matches (PSMs) after database searches is a major issue for proteogenomic studies using liquid-chromatography and mass-spectrometry-based large proteomic profiling. Here we developed a simple strategy for protein identification, with a controlled false discovery rate (FDR) at the protein level, using an integrated proteomic pipeline (IPP) that consists of four engrailed steps as follows. First, using three different search engines, SEQUEST, MASCOT, and MS-GF+, individual proteomic searches were performed against the neXtProt database. Second, the search results from the PSMs were combined using statistical evaluation tools including DTASelect and Percolator. Third, the peptide search scores were converted into E-scores normalized using an in-house program. Last, ProteinInferencer was used to filter the proteins containing two or more peptides with a controlled FDR of 1.0% at the protein level. Finally, we compared the performance of the IPP to a conventional proteomic pipeline (CPP) for protein identification using a controlled FDR of <1% at the protein level. Using the IPP, a total of 5756 proteins (vs 4453 using the CPP) including 477 alternative splicing variants (vs 182 using the CPP) were identified from human hippocampal tissue. In addition, a total of 10 missing proteins (vs 7 using the CPP) were identified with two or more unique peptides, and their tryptic peptides were validated using MS/MS spectral pattern from a repository database or their corresponding synthetic peptides. This study shows that the IPP effectively improved the identification of proteins, including alternative splicing variants and missing proteins, in human hippocampal tissues for the C-HPP. All RAW files used in this study were deposited in ProteomeXchange (PXD000395).

  12. Nonpeptide and peptide growth hormone secretagogues act both as ghrelin receptor agonist and as positive or negative allosteric modulators of ghrelin signaling

    DEFF Research Database (Denmark)

    Holst, Birgitte; Brandt, Erik; Bach, Anders

    2005-01-01

    Two nonpeptide (L692,429 and MK-677) and two peptide [GH-releasing peptide (GHRP)-6 and ghrelin] agonists were compared in binding and in signal transduction assays: calcium mobilization, inositol phosphate turnover, cAMP-responsive element (CRE), and serum-responsive element (SRE) controlled...... transcription, as well as arrestin mobilization. MK-677 acted as a simple agonist having an affinity of 6.5 nm and activated all signal transduction systems with similar high potency (0.2-1.4 nm). L-692,429 also displayed a very similar potency in all signaling assays (25-60 nm) but competed with a 1000-fold...... agonist properties and in their ability to modulate ghrelin signaling. A receptor model is presented wherein ghrelin normally only activates one receptor subunit in a dimer and where the smaller nonendogenous agonists bind in the other subunit to act both as coagonists and as either neutral (MK-677...

  13. False positive of the PET -CT with {sup 18}F.D.G. in the staging of Hodgkin lymphomas: about two cases;Faux positifs de la TEP-TDM au 18 FDG dans la stadification des lymphomes de hodgkin: a propos de deux cas

    Energy Technology Data Exchange (ETDEWEB)

    Caoduro, C.; Blagosklonov, O.; Angoue, O.; Ungureanu, C.M.; Quemard, G.; Porot, C.; Boulahdour, H. [Hopital Jean-Minjoz, Service de medecine nucleaire, 25 - Besancon (France); Lerais, J.M. [Hopital Jean-Minjoz, Service de radiologie, 25 - Besancon (France)

    2010-05-15

    An isolated hyper fixating bone lesion on a PET / CT performed for staging of lymphoma should suggest a false positive and take advantage of additional tests for etiological aim to allow proper staging of the disease and appropriate therapy. (N.C.)

  14. Multidisciplinary team review of best practices for collection and handling of blood cultures to determine effective interventions for increasing the yield of true-positive bacteremias, reducing contamination, and eliminating false-positive central line-associated bloodstream infections.

    Science.gov (United States)

    Garcia, Robert A; Spitzer, Eric D; Beaudry, Josephine; Beck, Cindy; Diblasi, Regina; Gilleeny-Blabac, Michelle; Haugaard, Carol; Heuschneider, Stacy; Kranz, Barbara P; McLean, Karen; Morales, Katherine L; Owens, Susan; Paciella, Mary E; Torregrosa, Edwin

    2015-11-01

    A literature search was conducted using keywords for articles published in English from January 1990 to March 2015. Using criteria related to blood culture collection and handling, the search yielded 101 articles. References used also included Microbiology Laboratory standards, guidelines, and textbook information. The literature identified diverse and complex issues surrounding blood culture practices, including the impact of false-positive results, laboratory definition of contamination, effect on central line-associated bloodstream infection (CLABSI) reporting, indications for collecting blood cultures, drawing from venipuncture sites versus intravascular catheters, selection of antiseptics, use of needleless connectors, inoculation of blood culture bottles, and optimizing program management in emergency departments, education, and implementation of bundled practice initiatives. Hospitals should optimize best practice in the collection, handling, and management of blood culture specimens, an often overlooked but essential component in providing optimal care of patients in all settings and populations, reducing financial burdens, and increasing the accuracy of reportable CLABSI. Although universal concepts exist in blood culture practices, some issues require further research to determine benefit. Institutions undertaking a review of their blood culture programs are encouraged to use a checklist that addresses elements that encompass the research contained in this review. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  15. How does serum brain natriuretic peptide level change under nasal continuous positive airway pressure in obstructive sleep apnea-hypopnea syndrome?

    Directory of Open Access Journals (Sweden)

    Sameh Msaad

    2016-08-01

    Full Text Available Background: Obstructive sleep apnea-hypopnea syndrome (OSAHS is associated with cardiovascular morbidity and mortality, which can be improved by using continuous positive airway pressure (CPAP therapy. However, the pathophysiological links between the two kinds of disease and the mechanism of the CPAP effect remain incompletely understood. We aimed to inquire into the myocardial involvement in this relationship. We suggested that serum brain natriuretic peptide (BNP is sensitive enough to detect myocardial stress caused by OSAHS. Design and methods: Sixty-four subjects without cardiovascular disease (21 controls, 24 normotensive OSAHS patients, and 19 hypertensive OSAHS patients were analyzed for serum BNP at baseline and serially over 6 months. CPAP was applied to 23 patients with severe OSAHS. Results: At baseline, the serum BNP levels were significantly higher (p=0.0001 in the OSAHS group (22.3±14.79 pg/ml than in the control group (9.2±6.75 pg/ml. Increased serum BNP levels were significantly associated with mean transcutaneous oxygen saturation (SpO2 (p<0.0001, minimal SpO2 (p=0.002, oxygen desaturation index (p=0.001, and total sleep time spent with SpO2 lower than 90% (p=0.002. All patients with elevated BNP levels (≥37 pg/ml had moderate or severe OSAHS (11/43 OSAHS patients. The more severe the OSAHS, the higher the BNP levels were. However, only the difference between severe and mild OSAHS was statistically significant (p=0.029. Hypertensive OSAHS patients had the highest baseline BNP levels (27.7±16.74 pg/ml. They were significantly higher (p=0.001 than in normotensive OSAHS patients (18±11.72 pg/ml (p=0.039 and the controls (9.2±6.75 pg/ml. As compared with baseline, treatment with CPAP significantly decreased BNP levels in both hypertensive and normotensive OSAHS patients (respectively, from 36±16.10 to 29.7±14.29 pg/ml, p<0.001, and from 20±10.09 to 16±8.98 pg/ml, p<0.001. In contrast, the BNP levels slightly increased

  16. False Memories for Affective Information in Schizophrenia.

    Science.gov (United States)

    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  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.

  17. False Memories for Affective Information in Schizophrenia

    Science.gov (United States)

    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 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

  18. Reduced False Memory after Sleep

    Science.gov (United States)

    Fenn, Kimberly M.; Gallo, David A.; Margoliash, Daniel; Roediger, Henry L., III; Nusbaum, Howard C.

    2009-01-01

    Several studies have shown that sleep contributes to the successful maintenance of previously encoded information. This research has focused exclusively on memory for studied events, as opposed to false memories. Here we report three experiments showing that sleep reduces false memories in the Deese-Roediger-McDermott (DRM) memory illusion. False…

  19. Unique thermal record in False Bay

    CSIR Research Space (South Africa)

    Grundlingh, ML

    1993-10-01

    Full Text Available Over the past decade False Bay has assumed a prime position in terms of research in to large South African bays. This is manifested by investigations that cover flow conditions modelling, thermal structure, management, biology and nutrients, geology...

  20. A Study of False-Positive and False-Negative Error Rates in Cartridge Case Comparisons

    Science.gov (United States)

    2014-04-07

    swg/index.php?option=com_content&view= article &id=5:testability-of-the- scientific -principle&catid=9:ark#CC Please note that there are tentative...materials for the study, in particular Vicki Sieve . 3 Abstract: This report provides the details for a study designed to...published by the Scientific Working Group for Firearms and Toolmarks (SWGGUN) maintains an extensive bibliography of literature relevant to the

  1. A phase I study of personalized peptide vaccination using 14 kinds of vaccine in combination with low-dose estramustine in HLA-A24-positive patients with castration-resistant prostate cancer.

    Science.gov (United States)

    Noguchi, Masanori; Uemura, Hirotsugu; Naito, Seiji; Akaza, Hideyuki; Yamada, Akira; Itoh, Kyogo

    2011-04-01

    To evaluate the safety, tolerability, immune response, and antitumor activity of a combination of personalized peptide vaccination (PPV) and estramustine phosphate (EMP) in patients with castration-resistant prostate cancer (CRPC). In a phase I dose-escalation study, four peptides showing the highest levels of peptide-specific immunoglobulin G (IgG) to 14 vaccine candidates (ITK-1) were subcutaneously injected every week in three different dose settings (1, 3, and 5 mg per peptide) for 6 weeks with a low dose of EMP, and the patients were followed by maximum 2 years extension study either weekly or bi-weekly six times PPV as one course with a low dose of EMP. Fifteen patients were enrolled in the phase I study. No serious treatment-related adverse events were observed. The most common adverse events were grade 2 skin reactions at the injection sites. The maximum acceptable dose of ITK-1 was 8.643 mg. There were no treatment-related systemic adverse events of grade 3 or more, and maximum tolerated dose could not be determined. Cytotoxic T lymphocyte responses measured by interferon-γ release assay were boosted in 10 of 15 (67%) patients, and IgG responses were boosted in 7 of 15 (47%) patients. Twelve patients proceeded to the extension study, and the median survival time was 23.8 months during a median follow-up of 23.8 months. PPV treatment for HLA-A24 positive patients with CRPC could be recommended for further stages of clinical trials because of its safety and the higher frequency of boosting immune responses. Copyright © 2010 Wiley-Liss, Inc.

  2. Ribosome evolution: Emergence of peptide synthesis machinery

    Indian Academy of Sciences (India)

    allows the histidine to position close to the PTC during the reaction, it may contribute to improving peptide bond formation. Thus, it is important to analyse biomolecular interactions in terms of the dynamic nature of the structure. 3. Origin of peptide bond formation and the RNA world. Minihelix-based peptide bond formation ...

  3. False memories for affective information in Schizophrenia

    Directory of Open Access Journals (Sweden)

    Beth Fairfield

    2016-11-01

    Full Text Available 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, twenty-four patients and twenty-four 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 (p0.05 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.

  4. True photographs and false memories.

    Science.gov (United States)

    Lindsay, D Stephen; Hagen, Lisa; Read, J Don; Wade, Kimberley A; Garry, Maryanne

    2004-03-01

    Some trauma-memory-oriented psychotherapists advise clients to review old family photo albums to cue suspected "repressed" memories of childhood sexual abuse. Old photos might cue long-forgotten memories, but when combined with other suggestive influences they might also contribute to false memories. We asked 45 undergraduates to work at remembering three school-related childhood events (two true events provided by parents and one pseudoevent). By random assignment, 23 subjects were also given their school classes' group photos from the years of the to-be-recalled events as memory cues. As predicted, the rate of false-memory reports was dramatically higher in the photo condition than in the no-photo condition. Indeed, the rate of false-memory reports in the photo condition was substantially higher than the rate in any previously published study.

  5. Antipattern and Code Smell False Positives: Preliminary Conceptualization and Classification

    NARCIS (Netherlands)

    F.A. Fontana (Francesca Arcelli); J. Dietrich (Jens); B. Walter (Bartosz); A. Yamashita (Aiko); M. Zanoni (Marco)

    2016-01-01

    textabstractAnti-patterns and code smells are archetypes used for describing software design shortcomings that can negatively affect software quality, in particular maintainability. Tools, metrics and methodologies have been developed to identify these archetypes, based on

  6. Breast density classification to reduce false positives in CADe systems.

    Science.gov (United States)

    Vállez, Noelia; Bueno, Gloria; Déniz, Oscar; Dorado, Julián; Seoane, José Antonio; Pazos, Alejandro; Pastor, Carlos

    2014-02-01

    This paper describes a novel weighted voting tree classification scheme for breast density classification. Breast parenchymal density is an important risk factor in breast cancer. Moreover, it is known that mammogram interpretation is more difficult when dense tissue is involved. Therefore, automated breast density classification may aid in breast lesion detection and analysis. Several classification methods have been compared and a novel hierarchical classification procedure of combined classifiers with linear discriminant analysis (LDA) is proposed as the best solution to classify the mammograms into the four BIRADS tissue classes. The classification scheme is based on 298 texture features. Statistical analysis to test the normality and homoscedasticity of the data was carried out for feature selection. Thus, only features that are influenced by the tissue type were considered. The novel classification techniques have been incorporated into a CADe system to drive the detection algorithms and tested with 1459 images. The results obtained on the 322 screen-film mammograms (SFM) of the mini-MIAS dataset show that 99.75% of samples were correctly classified. On the 1137 full-field digital mammograms (FFDM) dataset results show 91.58% agreement. The results of the lesion detection algorithms were obtained from modules integrated within the CADe system developed by the authors and show that using breast tissue classification prior to lesion detection leads to an improvement of the detection results. The tools enhance the detectability of lesions and they are able to distinguish their local attenuation without local tissue density constraints. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  7. Clinical significance: false positives in the estimation of individual change

    OpenAIRE

    Pardo Merino, Antonio; Ferrer, Rodrigo

    2013-01-01

    Tanto en la investigación aplicada como en la práctica clínica es habitual tener que evaluar el cambio que experimentan los pacientes como consecuencia del tratamiento que reciben. En este trabajo se valora el comportamiento de varios métodos estadísticos diseñados para estimar ese cambio. La valoración se ha centrado en un aspecto al que todavía no se le ha prestado atención: la tasa de falsos positivos. Para ello, se ha simulado una situación de no-cambio (diseño pre-post sin cambio entre e...

  8. Detection of Biological False Positive Syphilis Serum Reactions ...

    African Journals Online (AJOL)

    A comparative evaluation of reagin tests (Wassermann, VDRL, RPR) and fluorescent treponema antibody absorption tests (FTA-ABS) performed on blood specimens from 5 271 persons (2 493 pregnant women, 1 130 apparently healthy prospective employees, 1 345 newborn babies and 303 leprosy patients) showed that ...

  9. Maximizing the sensitivity and reliability of peptide identification in large-scale proteomic experiments by harnessing multiple search engines.

    Science.gov (United States)

    Yu, Wen; Taylor, J Alex; Davis, Michael T; Bonilla, Leo E; Lee, Kimberly A; Auger, Paul L; Farnsworth, Chris C; Welcher, Andrew A; Patterson, Scott D

    2010-03-01

    Despite recent advances in qualitative proteomics, the automatic identification of peptides with optimal sensitivity and accuracy remains a difficult goal. To address this deficiency, a novel algorithm, Multiple Search Engines, Normalization and Consensus is described. The method employs six search engines and a re-scoring engine to search MS/MS spectra against protein and decoy sequences. After the peptide hits from each engine are normalized to error rates estimated from the decoy hits, peptide assignments are then deduced using a minimum consensus model. These assignments are produced in a series of progressively relaxed false-discovery rates, thus enabling a comprehensive interpretation of the data set. Additionally, the estimated false-discovery rate was found to have good concordance with the observed false-positive rate calculated from known identities. Benchmarking against standard proteins data sets (ISBv1, sPRG2006) and their published analysis, demonstrated that the Multiple Search Engines, Normalization and Consensus algorithm consistently achieved significantly higher sensitivity in peptide identifications, which led to increased or more robust protein identifications in all data sets compared with prior methods. The sensitivity and the false-positive rate of peptide identification exhibit an inverse-proportional and linear relationship with the number of participating search engines.

  10. Peptide aldehyde inhibitors of bacterial peptide deformylases.

    Science.gov (United States)

    Durand, D J; Gordon Green, B; O'Connell, J F; Grant, S K

    1999-07-15

    Bacterial peptide deformylases (PDF, EC 3.5.1.27) are metalloenzymes that cleave the N-formyl groups from N-blocked methionine polypeptides. Peptide aldehydes containing a methional or norleucinal inhibited recombinant peptide deformylase from gram-negative Escherichia coli and gram-positive Bacillus subtilis. The most potent inhibitor was calpeptin, N-CBZ-Leu-norleucinal, which was a competitive inhibitor of the zinc-containing metalloenzymes, E. coli and B. subtilis PDF with Ki values of 26.0 and 55.6 microM, respectively. Cobalt-substituted E. coli and B. subtilis deformylases were also inhibited by these aldehydes with Ki values for calpeptin of 9.5 and 12.4 microM, respectively. Distinct spectral changes were observed upon binding of calpeptin to the Co(II)-deformylases, consistent with the noncovalent binding of the inhibitor rather than the formation of a covalent complex. In contrast, the chelator 1,10-phenanthroline caused the time-dependent inhibition of B. subtilis Co(II)-PDF activity with the loss of the active site metal. The fact that calpeptin was nearly equipotent against deformylases from both gram-negative and gram-positive bacterial sources lends further support to the idea that a single deformylase inhibitor might have broad-spectrum antibacterial activity. Copyright 1999 Academic Press.

  11. Correcting false positive medium-chain acyl-CoA dehydrogenase deficiency results from newborn screening; synthesis, purification, and standardization of branched-chain C8 acylcarnitines for use in their selective and accurate absolute quantitation by UHPLC-MS/MS.

    Science.gov (United States)

    Minkler, Paul E; Stoll, Maria S K; Ingalls, Stephen T; Hoppel, Charles L

    2017-04-01

    While selectively quantifying acylcarnitines in thousands of patient samples using UHPLC-MS/MS, we have occasionally observed unidentified branched-chain C8 acylcarnitines. Such observations are not possible using tandem MS methods, which generate pseudo-quantitative acylcarnitine "profiles". Since these "profiles" select for mass alone, they cannot distinguish authentic signal from isobaric and isomeric interferences. For example, some of the samples containing branched-chain C8 acylcarnitines were, in fact, expanded newborn screening false positive "profiles" for medium-chain acyl-CoA dehydrogenase deficiency (MCADD). Using our fast, highly selective, and quantitatively accurate UHPLC-MS/MS acylcarnitine determination method, we corrected the false positive tandem MS results and reported the sample results as normal for octanoylcarnitine (the marker for MCADD). From instances such as these, we decided to further investigate the presence of branched-chain C8 acylcarnitines in patient samples. To accomplish this, we synthesized and chromatographically characterized several branched-chain C8 acylcarnitines (in addition to valproylcarnitine): 2-methylheptanoylcarnitine, 6-methylheptanoylcarnitine, 2,2-dimethylhexanoylcarnitine, 3,3-dimethylhexanoylcarnitine, 3,5-dimethylhexanoylcarnitine, 2-ethylhexanoylcarnitine, and 2,4,4-trimethylpentanoylcarnitine. We then compared their behavior with branched-chain C8 acylcarnitines observed in patient samples and demonstrated our ability to chromographically resolve, and thus distinguish, octanoylcarnitine from branched-chain C8 acylcarnitines, correcting false positive MCADD results from expanded newborn screening. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. False air-bone gap.

    Science.gov (United States)

    Rudmin, F

    1983-01-01

    A single case is reported of a severely hearing-impaired child with a finding of a large air-bone gap on pure-tone audiometry on multiple tests. Exploratory surgery found normal middle ear function. Subsequent audiometry indicated the presence of a false air-bone gap resulting from vibrotactile responses. Test procedures for identifying vibrotactile responses are discussed.

  13. Evolutionary Psychology and False Confession

    Science.gov (United States)

    Bering, Jesse M.; Shackelford, Todd K.

    2005-01-01

    This paper presents comments on Kassin's review, (see record 2005-03019-002) of the psychology of false confessions. The authors note that Kassin's review makes a compelling argument for the need for legal reform in police interrogation practices. Because his work strikes at the heart of the American criminal justice system--its fairness--the…

  14. False set in aireated cements

    Directory of Open Access Journals (Sweden)

    Vázquez, T.

    1986-06-01

    Full Text Available The influence of aireation on the appearance or elimination of the false setting in industrial portland cements is studied by means of infrared spectroscopy.

    Se estudia por medio de la espectroscopia infrarroja la influencia de la aireación sobre la aparición o eliminación del fraguado, en cemento portland industriales.

  15. Sleep loss produces false memories.

    Science.gov (United States)

    Diekelmann, Susanne; Landolt, Hans-Peter; Lahl, Olaf; Born, Jan; Wagner, Ullrich

    2008-01-01

    People sometimes claim with high confidence to remember events that in fact never happened, typically due to strong semantic associations with actually encoded events. Sleep is known to provide optimal neurobiological conditions for consolidation of memories for long-term storage, whereas sleep deprivation acutely impairs retrieval of stored memories. Here, focusing on the role of sleep-related memory processes, we tested whether false memories can be created (a) as enduring memory representations due to a consolidation-associated reorganization of new memory representations during post-learning sleep and/or (b) as an acute retrieval-related phenomenon induced by sleep deprivation at memory testing. According to the Deese, Roediger, McDermott (DRM) false memory paradigm, subjects learned lists of semantically associated words (e.g., "night", "dark", "coal",...), lacking the strongest common associate or theme word (here: "black"). Subjects either slept or stayed awake immediately after learning, and they were either sleep deprived or not at recognition testing 9, 33, or 44 hours after learning. Sleep deprivation at retrieval, but not sleep following learning, critically enhanced false memories of theme words. This effect was abolished by caffeine administration prior to retrieval, indicating that adenosinergic mechanisms can contribute to the generation of false memories associated with sleep loss.

  16. Sleep loss produces false memories.

    Directory of Open Access Journals (Sweden)

    Susanne Diekelmann

    Full Text Available People sometimes claim with high confidence to remember events that in fact never happened, typically due to strong semantic associations with actually encoded events. Sleep is known to provide optimal neurobiological conditions for consolidation of memories for long-term storage, whereas sleep deprivation acutely impairs retrieval of stored memories. Here, focusing on the role of sleep-related memory processes, we tested whether false memories can be created (a as enduring memory representations due to a consolidation-associated reorganization of new memory representations during post-learning sleep and/or (b as an acute retrieval-related phenomenon induced by sleep deprivation at memory testing. According to the Deese, Roediger, McDermott (DRM false memory paradigm, subjects learned lists of semantically associated words (e.g., "night", "dark", "coal",..., lacking the strongest common associate or theme word (here: "black". Subjects either slept or stayed awake immediately after learning, and they were either sleep deprived or not at recognition testing 9, 33, or 44 hours after learning. Sleep deprivation at retrieval, but not sleep following learning, critically enhanced false memories of theme words. This effect was abolished by caffeine administration prior to retrieval, indicating that adenosinergic mechanisms can contribute to the generation of false memories associated with sleep loss.

  17. False Windows - Yesterday and Today

    Science.gov (United States)

    Niewitecki, Stefan

    2017-10-01

    The article is concerned with a very interesting aspect of architectural design, namely, a contradiction between the building functions and the necessity of giving the building a desired external appearance. One of the possibilities of reconciling this contradiction is using pseudo windows that are visible on the elevation and generally have the form of a black painted recess accompanied by frames and sashes and often single glazing. Of course, there are no windows or openings in the corresponding places in the walls inside the building. The article discusses the differences between false windows and blind widows (German: blende), also known as blank windows, which, in fact, are shallow recesses in the wall having the external appearance of an arcade or a window and which had already been used in Gothic architecture mostly for aesthetic reasons and sometimes to reduce the load of the wall. Moreover, the article describes various false windows that appeared later than blind windows because they did not appear until the 17th century. Contemporary false windows are also discussed and it is shown that contrary to the common belief they are widely used. In his research, the author not only used the Internet data but also carried out his own in situ exploration. The false windows constitute very interesting albeit rare elements of the architectural design of buildings. They have been used successfully for a few hundred years. It might seem that they should have been discarded by now but this has not happened. Quite contrary, since the second half of the 20th century there has been a rapid development of glass curtain walls that serve a similar function in contemporary buildings as the false windows once did, only in a more extensive way.

  18. Sleep loss produces false memories

    OpenAIRE

    Diekelmann, S; Landolt, H P; Lahl, O; Born, J; Wagner, U

    2008-01-01

    People sometimes claim with high confidence to remember events that in fact never happened, typically due to strong semantic associations with actually encoded events. Sleep is known to provide optimal neurobiological conditions for consolidation of memories for long-term storage, whereas sleep deprivation acutely impairs retrieval of stored memories. Here, focusing on the role of sleep-related memory processes, we tested whether false memories can be created (a) as enduring memory representa...

  19. Does sleep promote false memories?

    Science.gov (United States)

    Darsaud, Annabelle; Dehon, Hedwige; Lahl, Olaf; Sterpenich, Virginie; Boly, Mélanie; Dang-Vu, Thanh; Desseilles, Martin; Gais, Stephen; Matarazzo, Luca; Peters, Frédéric; Schabus, Manuel; Schmidt, Christina; Tinguely, Gilberte; Vandewalle, Gilles; Luxen, André; Maquet, Pierre; Collette, Fabienne

    2011-01-01

    Memory is constructive in nature so that it may sometimes lead to the retrieval of distorted or illusory information. Sleep facilitates accurate declarative memory consolidation but might also promote such memory distortions. We examined the influence of sleep and lack of sleep on the cerebral correlates of accurate and false recollections using fMRI. After encoding lists of semantically related word associates, half of the participants were allowed to sleep, whereas the others were totally sleep deprived on the first postencoding night. During a subsequent retest fMRI session taking place 3 days later, participants made recognition memory judgments about the previously studied associates, critical theme words (which had not been previously presented during encoding), and new words unrelated to the studied items. Sleep, relative to sleep deprivation, enhanced accurate and false recollections. No significant difference was observed in brain responses to false or illusory recollection between sleep and sleep deprivation conditions. However, after sleep but not after sleep deprivation (exclusive masking), accurate and illusory recollections were both associated with responses in the hippocampus and retrosplenial cortex. The data suggest that sleep does not selectively enhance illusory memories but rather tends to promote systems-level consolidation in hippocampo-neocortical circuits of memories subsequently associated with both accurate and illusory recollections. We further observed that during encoding, hippocampal responses were selectively larger for items subsequently accurately retrieved than for material leading to illusory memories. The data indicate that the early organization of memory during encoding is a major factor influencing subsequent production of accurate or false memories.

  20. A two-step database search method improves sensitivity in peptide sequence matches for metaproteomics and proteogenomics studies.

    Science.gov (United States)

    Jagtap, Pratik; Goslinga, Jill; Kooren, Joel A; McGowan, Thomas; Wroblewski, Matthew S; Seymour, Sean L; Griffin, Timothy J

    2013-04-01

    Large databases (>10(6) sequences) used in metaproteomic and proteogenomic studies present challenges in matching peptide sequences to MS/MS data using database-search programs. Most notably, strict filtering to avoid false-positive matches leads to more false negatives, thus constraining the number of peptide matches. To address this challenge, we developed a two-step method wherein matches derived from a primary search against a large database were used to create a smaller subset database. The second search was performed against a target-decoy version of this subset database merged with a host database. High confidence peptide sequence matches were then used to infer protein identities. Applying our two-step method for both metaproteomic and proteogenomic analysis resulted in twice the number of high confidence peptide sequence matches in each case, as compared to the conventional one-step method. The two-step method captured almost all of the same peptides matched by the one-step method, with a majority of the additional matches being false negatives from the one-step method. Furthermore, the two-step method improved results regardless of the database search program used. Our results show that our two-step method maximizes the peptide matching sensitivity for applications requiring large databases, especially valuable for proteogenomics and metaproteomics studies. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Psychoactive drugs and false memory: comparison of dextroamphetamine and δ-9-tetrahydrocannabinol on false recognition.

    Science.gov (United States)

    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.

  2. Revisiting the False Confession Problem.

    Science.gov (United States)

    Alvarez-Toro, Viviana; Lopez-Morales, Cesar A

    2018-03-01

    Despite the existence of important safeguards in our criminal legal system, innocent suspects often succumb to forceful and deceptive interrogation techniques. Among those over-represented members of the false confessor population are minors, people with cognitive and intellectual disabilities, and those with psychiatric disorders. Some of the confessions made by these at-risk populations can hardly be considered voluntary or reliable, but they are generally admitted at trial, regardless of their prejudicial effect. Forensic psychiatrists should become more involved in the overall process of evaluating confessions, not only testifying in courts, but also assisting policymakers in reforming the interrogation process and influencing the legal process. Thus, forensic psychiatrists may give their expert opinion by providing proper training to police interrogators and examining videotaped interrogations. In addition, forensic experts can be instrumental in contributing to three legal solutions that we propose to the false confession problem: a constitutional approach, an evidence law approach, and a jury instruction approach. Each of these approaches requires forensic psychiatrists to help judges and jurors understand the coercive nature of the interrogation process and its effect on suspects' behavior. © 2018 American Academy of Psychiatry and the Law.

  3. Bug Hunting with False Negatives

    NARCIS (Netherlands)

    Calamé, Jens; Ioustinova, Natalia; van de Pol, Jan Cornelis; Sidorova, Natalia; Davies, J.; Gibbons, J.

    Safe data abstractions are widely used for verification purposes. Positive verification results can be transferred from the abstract to the concrete system. When a property is violated in the abstract system, one still has to check whether a concrete violation scenario exists. However, even when the

  4. Antimicrobial Peptides

    Directory of Open Access Journals (Sweden)

    Ali Adem Bahar

    2013-11-01

    Full Text Available The rapid increase in drug-resistant infections has presented a serious challenge to antimicrobial therapies. The failure of the most potent antibiotics to kill “superbugs” emphasizes the urgent need to develop other control agents. Here we review the history and new development of antimicrobial peptides (AMPs, a growing class of natural and synthetic peptides with a wide spectrum of targets including viruses, bacteria, fungi, and parasites. We summarize the major types of AMPs, their modes of action, and the common mechanisms of AMP resistance. In addition, we discuss the principles for designing effective AMPs and the potential of using AMPs to control biofilms (multicellular structures of bacteria embedded in extracellular matrixes and persister cells (dormant phenotypic variants of bacterial cells that are highly tolerant to antibiotics.

  5. Cartilage oligomeric matrix protein associates differentially with erosions and synovitis and has a different temporal course in cyclic citrullinated peptide antibody (anti-CCP)-positive versus anti-CCP-negative early rheumatoid arthritis.

    Science.gov (United States)

    Christensen, Anne F; Lindegaard, Hanne; Hørslev-Petersen, Kim; Hetland, Merete L; Ejbjerg, Bo; Stengaard-Pedersen, Kristian; Jacobsen, Søren; Lottenburger, Tine; Ellingsen, Torkell; Andersen, Lis S; Hansen, Ib; Skjødt, Henrik; Pedersen, Jens K; Lauridsen, Ulrik B; Svendsen, Anders; Tarp, Ulrik; Pødenphant, Jan; Østergaard, Mikkel; Junker, Peter

    2011-08-01

    Cyclic citrullinated peptide antibody (anti-CCP)-positive and anti-CCP-negative rheumatoid arthritis (RA) have been suggested as 2 distinctive disease subsets with respect to disease activity and prognosis. Previously, we proposed that anti-CCP antibodies might have a chondrocyte-suppressive effect. We aimed to compare circulating cartilage oligomeric matrix protein (COMP), a marker of cartilage turnover, in untreated anti-CCP-positive and anti-CCP-negative RA, and to study the temporal pattern of COMP through 4 years of treatment, including the relationship to imaging and clinical findings. A total of 160 patients with newly diagnosed RA who were naive to disease-modifying antirheumatic drugs were included in the CIMESTRA trial. Ninety healthy blood donors served as controls. Demographic and disease measures including Disease Activity Score in 28 joints, IgM rheumatoid factor, anti-CCP, Health Assessment Questionnaire, visual analog scale scores for pain and global and physician assessment, and magnetic resonance imaging (MRI) of the nondominant hand were recorded at baseline. COMP in serum was measured by ELISA at inclusion and serially through 4 years. Median baseline COMP was higher in patients with RA [9.8 U/l (interquartile range 8.96, 10.5)] compared with controls [8.3 U/l (IQR 7.84, 8.9); p negative patients (p = 0.048). In anti-CCP-positive patients, COMP exhibited a parabolic course over 4 years, while COMP in anti-CCP-negative patients had an almost linear course. In anti-CCP-positive patients, COMP was associated with MRI edema and erosion score, while COMP was correlated with synovitis score in anti-CCP-negative individuals. Our study provides additional evidence for the existence of different disease pathways in anti-CCP-positive and anti-CCP-negative subsets of RA, and evidence that anti-CCP antibodies may be implicated in the disease process by modifying cartilage metabolism.

  6. White Rock in False Color

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] The THEMIS VIS camera is capable of capturing color images of the Martian surface using five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from using multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation. This false color image shows the wind eroded deposit in Pollack Crater called 'White Rock'. This image was collected during the Southern Fall Season. Image information: VIS instrument. Latitude -8, Longitude 25.2 East (334.8 West). 0 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington

  7. Mannose-binding lectin gene polymorphisms are associated with disease activity and physical disability in untreated, anti-cyclic citrullinated peptide-positive patients with early rheumatoid arthritis

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Garred, Peter; Madsen, Hans Ole

    2009-01-01

    OBJECTIVE: To study the association between polymorphisms in the mannose-binding lectin gene (MBL2) and disease activity, physical disability, and joint erosions in patients with newly diagnosed rheumatoid arthritis (RA). METHODS: Patients with early RA (n=158) not previously treated with disease...... activity by Disease Activity Score-28 (DAS28 score), physical disability by Health Assessment Questionnaire (HAQ) score, and erosive changes in hands and feet (Sharp-van der Heijde score). RESULTS: Eight patients were homozygous MBL2 defective (O/O), 101 belonged to an intermediate group, and 49 were MBL2...... high producers (YA/YA). Anti-CCP was present in 93 patients (59%). High scores of disease activity, C-reactive protein-based DAS28 (p=0.02), and physical disability by HAQ (p=0.01) were associated with high MBL2 expression genotypes in a gene-dose dependent way, but only in anti-CCP-positive patients...

  8. Peptide-membrane interactions of arginine-tryptophan peptides probed using quartz crystal microbalance with dissipation monitoring.

    KAUST Repository

    Rydberg, Hanna A

    2014-04-18

    Membrane-active peptides include peptides that can cross cellular membranes and deliver macromolecular cargo as well as peptides that inhibit bacterial growth. Some of these peptides can act as both transporters and antibacterial agents. It is desirable to combine the knowledge from these two different fields of membrane-active peptides into design of new peptides with tailored actions, as transporters of cargo or as antibacterial substances, targeting specific membranes. We have previously shown that the position of the amino acid tryptophan in the peptide sequence of three arginine-tryptophan peptides affects their uptake and intracellular localization in live mammalian cells, as well as their ability to inhibit bacterial growth. Here, we use quartz crystal microbalance with dissipation monitoring to assess the induced changes caused by binding of the three peptides to supported model membranes composed of POPC, POPC/POPG, POPC/POPG/cholesterol or POPC/lactosyl PE. Our results indicate that the tryptophan position in the peptide sequence affects the way these peptides interact with the different model membranes and that the presence of cholesterol in particular seems to affect the membrane interaction of the peptide with an even distribution of tryptophans in the peptide sequence. These results give mechanistic insight into the function of these peptides and may aid in the design of membrane-active peptides with specified cellular targets and actions.

  9. Synthetic antifreeze peptide

    OpenAIRE

    1991-01-01

    A synthetic antifreeze peptide and a synthetic gene coding for the antifreeze peptide have been produced. The antifreeze peptide has a greater number of repeating amino acid sequences than is present in the native antifreeze peptides from winter flounder upon which the synthetic antifreeze peptide was modeled. Each repeating amino acid sequence has two polar amino acid residues which are spaced a controlled distance apart so that the antifreeze peptide may inhibit ice formation. The synthetic...

  10. Il nuovo reato di false comunicazioni sociali

    Directory of Open Access Journals (Sweden)

    Lorenzo Maria Corvucci

    2015-12-01

    Full Text Available The author examines the new offence of false social communication introduced by the Italian law dated 27 may 2015 n.69 in force from 14 June 2015. Considering the modifications added to the new offence of false accounting- basically explained to highlight the novum - the attention is paid on a specific major issue, previously discussed by the fifth section of the Italian Supreme Court competent in this matter after a few months from the moment the new law came in force. The questions applies to the fact whether the fraudulent evidence should remain to be punishable as the new discipline has limited the object of the criminal conduct only to “material relevant facts which are untrue” or to the omission of material relevant facts whose communication is imposed by the law regulating the economic situation, the assets and financial position of the company or of the group to which the company belongs. In this way any reference to the evaluations contained in the text previously in force is eliminated. Omissive conduct is the new definition recalling the two previous rules (art. 2621 and 2622 of the Italian civil code.

  11. 19 CFR 111.32 - False information.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false False information. 111.32 Section 111.32 Customs... CUSTOMS BROKERS Duties and Responsibilities of Customs Brokers § 111.32 False information. A broker must... procure the giving of, any false or misleading information or testimony in any matter pending before the...

  12. Interaction of 18-residue peptides derived from amphipathic helical ...

    Indian Academy of Sciences (India)

    We investigated the interaction of six 18-residue peptides derived from amphipathic helical segments of globular proteins with model membranes. The net charge of the peptides at neutral pH varies from –1 to +6. Circular dichroism spectra indicate that peptides with a high net positive charge tend to fold into a helical ...

  13. Identification of binding peptides of the ADAM15 disintegrin domain ...

    Indian Academy of Sciences (India)

    Madhsudhan

    ADAM15 disintegrin domain (RADD) that could inhibit melanoma cell adhesion by using Escherichia coli. Second, four specific binding peptides (peptides A, B, C, and D) were selected using a phage display 12-mer peptide library. The screening protocol involved 4 rounds of positive panning on RADD and 2 rounds of ...

  14. Human peptide transporters

    DEFF Research Database (Denmark)

    Nielsen, Carsten Uhd; Brodin, Birger; Jørgensen, Flemming Steen

    2002-01-01

    Peptide transporters are epithelial solute carriers. Their functional role has been characterised in the small intestine and proximal tubules, where they are involved in absorption of dietary peptides and peptide reabsorption, respectively. Currently, two peptide transporters, PepT1 and PepT2, wh...

  15. [SYNTHETIC PEPTIDE VACCINES].

    Science.gov (United States)

    Sergeyev, O V; Barinsky, I F

    2016-01-01

    An update on the development and trials of synthetic peptide vaccines is reviewed. The review considers the successful examples of specific protection as a result of immunization with synthetic peptides using various protocols. The importance of conformation for the immunogenicity of the peptide is pointed out. An alternative strategy of the protection of the organism against the infection using synthetic peptides is suggested.

  16. Motivated Reconstruction: The Effect of Brand Commitment on False Memories.

    Science.gov (United States)

    Montgomery, Nicole Votolato; Rajagopal, Priyali

    2018-02-01

    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).

  17. Not All False Memories Are Created Equal

    OpenAIRE

    Nichols, Rebecca Michelle

    2014-01-01

    Though there has been an abundance of experimental research in false memory phenomena over the last several decades, there is a surprising dearth of studies that examine whether or not people who are susceptible to false memories in certain conditions are also susceptible to false memories under other conditions. The dissertation research presented here addresses this issue. In one large study, subjects participated in three well-established false memory paradigms (a misinformation task, the ...

  18. Attitude Importance and the False Consensus Effect.

    Science.gov (United States)

    Fabrigar, Leandre R.; Krosnick, Jon A.

    1995-01-01

    Explores the possibility that importance may regulate the magnitude of the false consensus effect. Analysis revealed a strong false consensus effect but no reliable relation between its magnitude and attitude importance. Results contradict assumptions that the false consensus effect arises from attitudes that directly or indirectly influence…

  19. Discriminating between true-positive and false-positive clinical mastitis alerts from automatic milking systems

    NARCIS (Netherlands)

    Steeneveld, W.; Gaag, van der L.C.; Ouweltjes, W.; Mollenhorst, H.; Hogeveen, H.

    2010-01-01

    Automatic milking systems (AMS) generate alert lists reporting cows likely to have clinical mastitis (CM). Dutch farmers indicated that they use non-AMS cow information or the detailed alert information from the AMS to decide whether to check an alerted cow for CM. However, it is not yet known to

  20. Disfluent presentations lead to the creation of more false memories.

    Science.gov (United States)

    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.

  1. Voting experiments: Bandwagon voting or false-consensus effect?

    OpenAIRE

    Ivo Bischoff; Henrik Egbert

    2008-01-01

    In an experiment designed to test for expressive voting, Tyran (JPubEc 2004) found a strong positive correlation between the participants' approval for a proposal to donate money for charity and their expected approval rate for fellow voters. This phenomenon can be due to bandwagon voting or a false consensus effect. The social science literature reports both effects for voting decisions. Replicating Tyran's experiment and adding new treatments, we provide evidence for a false consensus effec...

  2. Importing perceived features into false memories.

    Science.gov (United States)

    Lyle, Keith B; Johnson, Marcia K

    2006-02-01

    False memories sometimes contain specific details, such as location or colour, about events that never occurred. Based on the source-monitoring framework, we investigated one process by which false memories acquire details: the reactivation and misattribution of feature information from memories of similar perceived events. In Experiments 1A and 1B, when imagined objects were falsely remembered as seen, participants often reported that the objects had appeared in locations where visually or conceptually similar objects, respectively, had actually appeared. Experiment 2 indicated that colour and shape features of seen objects were misattributed to false memories of imagined objects. Experiment 3 showed that perceived details were misattributed to false memories of objects that had not been explicitly imagined. False memories that imported perceived features, compared to those that presumably did not, were subjectively more like memories for perceived events. Thus, perception may be even more pernicious than imagination in contributing to false memories.

  3. Acetylcholine promotes Ca2+ and NO-oscillations in adipocytes implicating Ca2+→NO→cGMP→cADP-ribose→Ca2+ positive feedback loop--modulatory effects of norepinephrine and atrial natriuretic peptide.

    Directory of Open Access Journals (Sweden)

    Egor A Turovsky

    Full Text Available This study investigated possible mechanisms of autoregulation of Ca(2+ signalling pathways in adipocytes responsible for Ca(2+ and NO oscillations and switching phenomena promoted by acetylcholine (ACh, norepinephrine (NE and atrial natriuretic peptide (ANP.Fluorescent microscopy was used to detect changes in Ca(2+ and NO in cultures of rodent white adipocytes. Agonists and inhibitors were applied to characterize the involvement of various enzymes and Ca(2+-channels in Ca(2+ signalling pathways.ACh activating M3-muscarinic receptors and Gβγ protein dependent phosphatidylinositol 3 kinase induces Ca(2+ and NO oscillations in adipocytes. At low concentrations of ACh which are insufficient to induce oscillations, NE or α1, α2-adrenergic agonists act by amplifying the effect of ACh to promote Ca(2+ oscillations or switching phenomena. SNAP, 8-Br-cAMP, NAD and ANP may also produce similar set of dynamic regimes. These regimes arise from activation of the ryanodine receptor (RyR with the implication of a long positive feedback loop (PFL: Ca(2+→NO→cGMP→cADPR→Ca(2+, which determines periodic or steady operation of a short PFL based on Ca(2+-induced Ca(2+ release via RyR by generating cADPR, a coagonist of Ca(2+ at the RyR. Interplay between these two loops may be responsible for the observed effects. Several other PFLs, based on activation of endothelial nitric oxide synthase or of protein kinase B by Ca(2+-dependent kinases, may reinforce functioning of main PFL and enhance reliability. All observed regimes are independent of operation of the phospholipase C/Ca(2+-signalling axis, which may be switched off due to negative feedback arising from phosphorylation of the inositol-3-phosphate receptor by protein kinase G.This study presents a kinetic model of Ca(2+-signalling system operating in adipocytes and integrating signals from various agonists, which describes it as multivariable multi feedback network with a family of nested positive

  4. Too Good to be False: Nonsignificant Results Revisited

    Directory of Open Access Journals (Sweden)

    Chris H. J. Hartgerink

    2017-03-01

    Full Text Available Due to its probabilistic nature, Null Hypothesis Significance Testing (NHST is subject to decision errors. The concern for false positives has overshadowed the concern for false negatives in the recent debates in psychology. This might be unwarranted, since reported statistically nonsignificant findings may just be ‘too good to be false’. We examined evidence for false negatives in nonsignificant results in three different ways. We adapted the Fisher test to detect the presence of at least one false negative in a set of statistically nonsignificant results. Simulations show that the adapted Fisher method generally is a powerful method to detect false negatives. We examined evidence for false negatives in the psychology literature in three applications of the adapted Fisher method. These applications indicate that (i the observed effect size distribution of nonsignificant effects exceeds the expected distribution assuming a null-effect, and approximately two out of three (66.7% psychology articles reporting nonsignificant results contain evidence for at least one false negative, (ii nonsignificant results on gender effects contain evidence of true nonzero effects, and (iii the statistically nonsignificant replications from the Reproducibility Project Psychology (RPP do not warrant strong conclusions about the absence or presence of true zero effects underlying these nonsignificant results. We conclude that false negatives deserve more attention in the current debate on statistical practices in psychology. Potentially neglecting effects due to a lack of statistical power can lead to a waste of research resources and stifle the scientific discovery process.

  5. Individual differences and the creation of false childhood memories.

    Science.gov (United States)

    Hyman, I E; Billings, F J

    1998-01-01

    We investigated if college students will create false childhood memories, the role of self-knowledge in memory creation, and if there are reliable individual differences related to memory creation. Based on information obtained from parents, we asked college students about several true childhood experiences. We also asked each student about one false event and presented the false event as if it was based on parent information. We asked the students to describe all events in two interviews separated by one day. When participants could not recall an event (whether true or false), we encouraged them to think about related self-knowledge and to try to imagine the event. In an unrelated experimental session, the students were administered four cognitive/personality scales: the Creative Imagination Scale (CIS), the Tellegen Absorption Scale (TAS), the Dissociative Experiences Scale (DES), and the Marlowe-Crowne Social Desirability Scale (SDS). We found that approximately 25% of the students created false childhood memories. Participants who made connections to related self-knowledge in the first interview were more likely to create false memories. We also found that the CIS and the DES were positively related to memory creation. Factors that decrease one's ability to engage in reality monitoring are related to the acceptance of false events and the creation of false memories.

  6. 19 CFR 11.13 - False designations of origin and false descriptions; false marking of articles of gold or silver.

    Science.gov (United States)

    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...

  7. False confessions: causes, consequences, and implications.

    Science.gov (United States)

    Leo, Richard A

    2009-01-01

    In the past two decades, hundreds of convicted prisoners have been exonerated by DNA and non-DNA evidence, revealing that police-induced false confessions are a leading cause of wrongful conviction of the innocent. In this article, empirical research on the causes and correlates of false confessions is reviewed. After a description of the three sequential processes that are responsible for the elicitation of false confessions--misclassification, coercion, and contamination--the three psychologically distinct types of false confession (voluntary, compliant, and persuaded) are discussed along with the consequences of introducing false-confession evidence in the criminal justice system. The article concludes with a brief discussion of the implications of empirical research for reducing the number of false confessions and improving the accuracy of confession evidence that is introduced against a defendant at trial.

  8. Peptide Vaccines for Cancer

    Directory of Open Access Journals (Sweden)

    Kono K

    2013-10-01

    Full Text Available Background: In general, the preferable characteristic of the target molecules for development of cancer vaccines are high immunogenicity, very common expression in cancer cells, specific expression in cancer cells and essential molecules for cell survival (to avoid loss of expression. We previously reported that three novel HLA-A24-restricted immunodominant peptides, which were derived from three different oncoantigens, TTK, LY6K, and IMP-3,were promising targets for cancer vaccination for esophageal squamous cell carcinoma (ESCCpatients. Then, we had performed a phase I clinical trial using three HLA-A24-binding peptides and the results had been shown to be promising for ESCC. Therefore, we further performed a multicenter, non-randomized phase II clinical trial. Patients and Methods: Sixty ESCC patients were enrolled to evaluate OS, PFS, immunological response employing ELISPOT and pentamer assays. Each of the three peptides was administered with IFA weekly. All patients received the vaccination without knowing an HLA-A type, and the HLA types were key-opened at the analysis point. Hence, the endpoints were set to evaluate differences between HLA-A*2402-positive (24(+ and -negative (24(- groups. Results: The OS in the 24 (+ group (n=35 tended to be better than that in the 24(- group (n=25 (MST 4.6 vs. 2.6 month, respectively, p = 0.121, although the difference was not statistically significant. However, the PFS in the 24(+ group was significantly better than that in the 24(- group (p = 0.032. In the 24(+ group, ELISPOT assay indicated that the LY6K-, TTK-, and IMP3-specific CTL responses were observed after the vaccination in 63%, 45%, and 60% of the 24(+ group, respectively. The patients having LY6K-, TTK-, and IMP3-specific CTL responses revealed the better OS than those not having CTL induction, respectively. The patients showing the CTL induction for multiple peptides have better clinical responses. Conclusion: The immune response induced

  9. Albumin-derived peptides efficiently reduce renal uptake of radiolabelled peptides

    International Nuclear Information System (INIS)

    Vegt, Erik; Eek, Annemarie; Oyen, Wim J.G.; Gotthardt, Martin; Boerman, Otto C.; Jong, Marion de

    2010-01-01

    In peptide-receptor radionuclide therapy (PRRT), the maximum activity dose that can safely be administered is limited by high renal uptake and retention of radiolabelled peptides. The kidney radiation dose can be reduced by coinfusion of agents that competitively inhibit the reabsorption of radiolabelled peptides, such as positively charged amino acids, Gelofusine, or trypsinised albumin. The aim of this study was to identify more specific and potent inhibitors of the kidney reabsorption of radiolabelled peptides, based on albumin. Albumin was fragmented using cyanogen bromide and six albumin-derived peptides with different numbers of electric charges were selected and synthesised. The effect of albumin fragments (FRALB-C) and selected albumin-derived peptides on the internalisation of 111 In-albumin, 111 In-minigastrin, 111 In-exendin and 111 In-octreotide by megalin-expressing cells was assessed. In rats, the effect of Gelofusine and albumin-derived peptides on the renal uptake and biodistribution of 111 In-minigastrin, 111 In-exendin and 111 In-octreotide was determined. FRALB-C significantly reduced the uptake of all radiolabelled peptides in vitro. The albumin-derived peptides showed different potencies in reducing the uptake of 111 In-albumin, 111 In-exendin and 111 In-minigastrin in vitro. The most efficient albumin-derived peptide (peptide 6), was selected for in vivo testing. In rats, 5 mg of peptide 6 very efficiently inhibited the renal uptake of 111 In-minigastrin, by 88%. Uptake of 111 In-exendin and 111 In-octreotide was reduced by 26 and 33%, respectively. The albumin-derived peptide 6 efficiently inhibited the renal reabsorption of 111 In-minigastrin, 111 In-exendin and 111 In-octreotide and is a promising candidate for kidney protection in PRRT. (orig.)

  10. PeptideAtlas

    Data.gov (United States)

    U.S. Department of Health & Human Services — PeptideAtlas is a multi-organism, publicly accessible compendium of peptides identified in a large set of tandem mass spectrometry proteomics experiments. Mass...

  11. Constructing rich false memories of committing crime.

    Science.gov (United States)

    Shaw, Julia; Porter, Stephen

    2015-03-01

    Memory researchers long have speculated that certain tactics may lead people to recall crimes that never occurred, and thus could potentially lead to false confessions. This is the first study to provide evidence suggesting that full episodic false memories of committing crime can be generated in a controlled experimental setting. With suggestive memory-retrieval techniques, participants were induced to generate criminal and noncriminal emotional false memories, and we compared these false memories with true memories of emotional events. After three interviews, 70% of participants were classified as having false memories of committing a crime (theft, assault, or assault with a weapon) that led to police contact in early adolescence and volunteered a detailed false account. These reported false memories of crime were similar to false memories of noncriminal events and to true memory accounts, having the same kinds of complex descriptive and multisensory components. It appears that in the context of a highly suggestive interview, people can quite readily generate rich false memories of committing crime.

  12. Designer Natriuretic Peptides

    Science.gov (United States)

    Lee, Candace Y. W.; Lieu, Hsiao; Burnett, John C.

    2011-01-01

    Designer natriuretic peptides (NPs) are novel hybrid peptides that are engineered from the native NPs through addition, deletion, or substitution of amino acid(s) with a goal toward optimization of pharmacological actions while minimizing undesirable effects. In this article, selected peptides that were designed in our laboratory are reviewed, and future directions for research and development of designer NPs are discussed. PMID:19158603

  13. Antimicrobial Peptides in 2014

    Directory of Open Access Journals (Sweden)

    Guangshun Wang

    2015-03-01

    Full Text Available This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms.

  14. Peptide Nucleic Acid Synthons

    DEFF Research Database (Denmark)

    2004-01-01

    A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  15. Peptide-Carrier Conjugation

    DEFF Research Database (Denmark)

    Hansen, Paul Robert

    2015-01-01

    To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined....

  16. Peptide Nucleic Acids

    DEFF Research Database (Denmark)

    2003-01-01

    A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  17. Peptide Nucleic Acids (PNA)

    DEFF Research Database (Denmark)

    2002-01-01

    A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  18. Peptide Nucleic Acids

    DEFF Research Database (Denmark)

    1998-01-01

    A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

  19. Social influence and mental routes to the production of authentic false memories and inauthentic false memories.

    Science.gov (United States)

    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.

  20. New false color mapping for image fusion

    NARCIS (Netherlands)

    Toet, A.; Walraven, J.

    1996-01-01

    A pixel based colour mapping algorithm is presented that produces a fused false colour rendering of two gray level images representing different sensor modalities. The result-ing fused false colour images have a higher information content than each of the original images and retain sensor-specific

  1. Effects of Instructions on False Recognition.

    Science.gov (United States)

    Mueller, John H.; And Others

    Four experiments were conducted to examine the effects of various processing instructions on the rate of false recognition. The continuous single-item procedure was used, and false recognitions of four types were examined: synonyms, antonyms, nonsemantic associates, and homonyms. The instructions encouraged subjects to think of associates, usages…

  2. False Discovery Rates and Multiple Testing

    Indian Academy of Sciences (India)

    IAS Admin

    RESONANCE | December 2013. GENERAL | ARTICLE. False Discovery Rates and Multiple Testing. Soumen Dey and Mohan Delampady. Keywords. False discovery rate, FDR,. pFDR, multiple testing, empiri- cal Bayes, hierarchical Bayes, high-dimensional problems. Soumen Dey is a research scholar at ISI, Bangalore.

  3. How Does Distinctive Processing Reduce False Recall?

    Science.gov (United States)

    Hunt, R. Reed; Smith, Rebekah E.; Dunlap, Kathryn R.

    2011-01-01

    False memories arising from associatively related lists are a robust phenomenon that resists many efforts to prevent it. However, a few variables have been shown to reduce this form of false memory. Explanations for how the reduction is accomplished have focused on either output monitoring processes or constraints on access, but neither idea alone…

  4. Explaining the Development of False Memories.

    Science.gov (United States)

    Reyna, Valerie F.; Holliday, Robyn; Marche, Tammy

    2002-01-01

    Reviews explanatory dimensions of children's false memory relevant to forensic practice: measurement, development, social factors, individual differences, varieties of memories and memory judgments, and varieties of procedures inducing false memories. Asserts that recent studies fail to use techniques that separate acquiescence from memory…

  5. Can False Memories Prime Problem Solutions?

    Science.gov (United States)

    Howe, Mark L.; Garner, Sarah R.; Dewhurst, Stephen A.; Ball, Linden J.

    2010-01-01

    Previous research has suggested that false memories can prime performance on related implicit and explicit memory tasks. The present research examined whether false memories can also be used to prime higher order cognitive processes, namely, insight-based problem solving. Participants were asked to solve a number of compound remote associate task…

  6. Rapid induction of false memory for pictures.

    Science.gov (United States)

    Weinstein, Yana; Shanks, David R

    2010-07-01

    Recognition of pictures is typically extremely accurate, and it is thus unclear whether the reconstructive nature of memory can yield substantial false recognition of highly individuated stimuli. A procedure for the rapid induction of false memories for distinctive colour photographs is proposed. Participants studied a set of object pictures followed by a list of words naming those objects, but embedded in the list were names of unseen objects. When subsequently shown full colour pictures of these unseen objects, participants consistently claimed that they had seen them, while discriminating with high accuracy between studied pictures and new pictures whose names did not appear in the misleading word list. These false memories can be reported with high confidence as well as the feeling of recollection. This new procedure allows the investigation of factors that influence false memory reports with ecologically valid stimuli and of the similarities and differences between true and false memories.

  7. Priming analogical reasoning with false memories.

    Science.gov (United States)

    Howe, Mark L; Garner, Sarah R; Threadgold, Emma; Ball, Linden J

    2015-08-01

    Like true memories, false memories are capable of priming answers to insight-based problems. Recent research has attempted to extend this paradigm to more advanced problem-solving tasks, including those involving verbal analogical reasoning. However, these experiments are constrained inasmuch as problem solutions could be generated via spreading activation mechanisms (much like false memories themselves) rather than using complex reasoning processes. In three experiments we examined false memory priming of complex analogical reasoning tasks in the absence of simple semantic associations. In Experiment 1, we demonstrated the robustness of false memory priming in analogical reasoning when backward associative strength among the problem terms was eliminated. In Experiments 2a and 2b, we extended these findings by demonstrating priming on newly created homonym analogies that can only be solved by inhibiting semantic associations within the analogy. Overall, the findings of the present experiments provide evidence that the efficacy of false memory priming extends to complex analogical reasoning problems.

  8. A workflow for peptide-based proteomics in a poorly sequenced plant: A case study on the plasma membrane proteome of banana

    DEFF Research Database (Denmark)

    Vertommen, A.; Laurell Blom Møller, Anders; Cordewener, J. H. G.

    2011-01-01

    for membrane proteomics. However, their application in non-model plants demands special precautions to prevent false positive identification of proteins.In the current paper, a workflow for membrane proteomics in banana, a poorly sequenced plant, is proposed. The main steps of this workflow are (i......) optimization of the peptide separation, (ii) performing de novo sequencing to allow a sequence homology search and (iii) visualization of identified peptide–protein associations using Cytoscape to remove redundancy and wrongly assigned peptides, based on species-specific information. By applying this workflow...

  9. Belief and sign, true and false: the unique of false belief reasoning.

    Science.gov (United States)

    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.

  10. Teacher Education and the Enduring Significance of "False Empathy"

    Science.gov (United States)

    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…

  11. Viscoelastic properties of the false vocal fold

    Science.gov (United States)

    Chan, Roger W.

    2004-05-01

    The biomechanical properties of vocal fold tissues have been the focus of many previous studies, as vocal fold viscoelasticity critically dictates the acoustics and biomechanics of phonation. However, not much is known about the viscoelastic response of the ventricular fold or false vocal fold. It has been shown both clinically and in computer simulations that the false vocal fold may contribute significantly to the aerodynamics and sound generation processes of human voice production, with or without flow-induced oscillation of the false fold. To better understand the potential role of the false fold in phonation, this paper reports some preliminary measurements on the linear and nonlinear viscoelastic behavior of false vocal fold tissues. Linear viscoelastic shear properties of human false fold tissue samples were measured by a high-frequency controlled-strain rheometer as a function of frequency, and passive uniaxial tensile stress-strain response of the tissue samples was measured by a muscle lever system as a function of strain and loading rate. Elastic moduli (Young's modulus and shear modulus) of the false fold tissues were calculated from the measured data. [Work supported by NIH.

  12. An association account of false belief understanding.

    Science.gov (United States)

    De Bruin, L C; Newen, A

    2012-05-01

    The elicited-response false belief task has traditionally been considered as reliably indicating that children acquire an understanding of false belief around 4 years of age. However, recent investigations using spontaneous-response tasks suggest that false belief understanding emerges much earlier. This leads to a developmental paradox: if young infants already understand false belief, then why do they fail the elicited-response false belief task? We postulate two systems to account for the development of false belief understanding: an association module, which provides infants with the capacity to register congruent associations between agents and objects, and an operating system, which allows them to transform these associations into incongruent associations through a process of inhibition, selection and representation. The interaction between the association module and the operating system enables infants to register increasingly complex associations on the basis of another agent's movements, visual perspective and propositional attitudes. This allows us account for the full range of findings on false belief understanding. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Acylation of Therapeutic Peptides

    DEFF Research Database (Denmark)

    Trier, Sofie; Henriksen, Jonas Rosager; Jensen, Simon Bjerregaard

    to the harsh and selective gastrointestinal system, and development has lacked far behind injection therapy. Peptide acylation is a powerful tool to alter the pharmacokinetics, biophysical properties and chemical stability of injectable peptide drugs, primarily used to prolong blood circulation....... This work aims to characterize acylated analogues of two therapeutic peptides by systematically increasing acyl chain length in order to elucidate its influence on membrane interaction and intestinal cell translocation in vitro. The studied peptides are the 33 amino acid Glucagon-like peptide-2 (GLP-2...... peptides can increase in vitro intestinal permeability, modestly for GLP-2 and drastically for sCT, and might benefit oral delivery. GLP-2 results provide a well-founded predictive power for future peptide analogues, whereas sCT results hold great promise for future analogues, albeit with a larger...

  14. Are trauma victims susceptible to "false memories"?

    Science.gov (United States)

    Zoellner, Lori A; Foa, Edna B; Brigidi, Bartholomew D; Przeworski, Amy

    2000-08-01

    Laboratory studies using word-list paradigms have provided evidence that nontraumatized individuals falsely recall or recognize events that never occurred. In the present study, H. L. Roediger and K. B. McDermott's false-memory paradigm (1995) was utilized to examine possible source monitoring deficits in individuals with PTSD. Traumatized individuals with PTSD were compared with traumatized individuals without PTSD and with nontraumatized control participants. Participants heard lists of related words (e.g., bed, night) that were associates of a critical nonpresented word (e.g., sleep) and were given immediate free recall and later recognition tests. Traumatized participants with and without PTSD generated more false recalls of critical nonpresented words than did nontraumatized participants. False recall was related to trait anxiety and PTSD severity. The results are consistent with a general source-monitoring deficit in trauma-exposed individuals.

  15. Sleep deprivation increases formation of false memory

    OpenAIRE

    Lo, June C.; Chong, Pearlynne L. H.; Ganesan, Shankari; Leong, Ruth L. F.; Chee, Michael W. L.

    2016-01-01

    Summary Retrieving false information can have serious consequences. Sleep is important for memory, but voluntary sleep curtailment is becoming more rampant. Here, the misinformation paradigm was used to investigate false memory formation after 1 night of total sleep deprivation in healthy young adults (N?=?58, mean age???SD?=?22.10???1.60?years; 29 males), and 7 nights of partial sleep deprivation (5?h sleep opportunity) in these young adults and healthy adolescents (N?=?54, mean age???SD?=?1...

  16. Cell Penetrating Peptides and Cationic Antibacterial Peptides

    Science.gov (United States)

    Rodriguez Plaza, Jonathan G.; Morales-Nava, Rosmarbel; Diener, Christian; Schreiber, Gabriele; Gonzalez, Zyanya D.; Lara Ortiz, Maria Teresa; Ortega Blake, Ivan; Pantoja, Omar; Volkmer, Rudolf; Klipp, Edda; Herrmann, Andreas; Del Rio, Gabriel

    2014-01-01

    Cell penetrating peptides (CPP) and cationic antibacterial peptides (CAP) have similar physicochemical properties and yet it is not understood how such similar peptides display different activities. To address this question, we used Iztli peptide 1 (IP-1) because it has both CPP and CAP activities. Combining experimental and computational modeling of the internalization of IP-1, we show it is not internalized by receptor-mediated endocytosis, yet it permeates into many different cell types, including fungi and human cells. We also show that IP-1 makes pores in the presence of high electrical potential at the membrane, such as those found in bacteria and mitochondria. These results provide the basis to understand the functional redundancy of CPPs and CAPs. PMID:24706763

  17. Visual false memories in posttraumatic stress disorder.

    Science.gov (United States)

    Moradi, Ali Reza; Heydari, Ali Hosain; Abdollahi, Mohammad Hossain; Rahimi-Movaghar, Vafa; Dalgleish, Tim; Jobson, Laura

    2015-11-01

    This study investigated visual false memories in posttraumatic stress disorder (PTSD). The Scenic False Memory paradigm (SFM, Hauschildt, Peters, Jelinek, & Moritz, 2012) was administered to male Iranian military personnel who had participated in the Iran-Iraq war and were diagnosed with (n = 21) or without (n = 21) PTSD and a sample of healthy male non-trauma-exposed controls (n = 21). Trauma-exposed participants recalled and recognized a significantly lower percentage of hits and a significantly greater percentage of false memories for both trauma-related and non-trauma-related video scenes, than non-trauma-exposed controls. Among the trauma-exposed participants, those with and without PTSD did not differ significantly in terms of percentage of hits and false memories recalled on the SFM. Those with PTSD were found to recognize significantly fewer hits for both the trauma-related and non-trauma-related videos than those without PTSD. Those with PTSD also recognized significantly more false memories for the trauma video scene than the non-PTSD group. The findings suggest that those with trauma exposure, and in particular those with PTSD, may have a greater susceptibility to visual false memory. (c) 2015 APA, all rights reserved).

  18. De-novo design of antimicrobial peptides for plant protection.

    Directory of Open Access Journals (Sweden)

    Benjamin Zeitler

    Full Text Available This work describes the de-novo design of peptides that inhibit a broad range of plant pathogens. Four structurally different groups of peptides were developed that differ in size and position of their charged and hydrophobic clusters and were assayed for their ability to inhibit bacterial growth and fungal spore germination. Several peptides are highly active at concentrations between 0,1 and 1 µg/ml against plant pathogenic bacteria, such as Pseudomonas syringae, Pectobacterium carotovorum, and Xanthomonas vesicatoria. Importantly, no hemolytic activity could be detected for these peptides at concentrations up to 200 µg/ml. Moreover, the peptides are also active after spraying on the plant surface demonstrating a possible way of application. In sum, our designed peptides represent new antimicrobial agents and with the increasing demand for antimicrobial compounds for production of "healthy" food, these peptides might serve as templates for novel antibacterial and antifungal agents.

  19. Plant peptide hormone signalling.

    Science.gov (United States)

    Motomitsu, Ayane; Sawa, Shinichiro; Ishida, Takashi

    2015-01-01

    The ligand-receptor-based cell-to-cell communication system is one of the most important molecular bases for the establishment of complex multicellular organisms. Plants have evolved highly complex intercellular communication systems. Historical studies have identified several molecules, designated phytohormones, that function in these processes. Recent advances in molecular biological analyses have identified phytohormone receptors and signalling mediators, and have led to the discovery of numerous peptide-based signalling molecules. Subsequent analyses have revealed the involvement in and contribution of these peptides to multiple aspects of the plant life cycle, including development and environmental responses, similar to the functions of canonical phytohormones. On the basis of this knowledge, the view that these peptide hormones are pivotal regulators in plants is becoming increasingly accepted. Peptide hormones are transcribed from the genome and translated into peptides. However, these peptides generally undergo further post-translational modifications to enable them to exert their function. Peptide hormones are expressed in and secreted from specific cells or tissues. Apoplastic peptides are perceived by specialized receptors that are located at the surface of target cells. Peptide hormone-receptor complexes activate intracellular signalling through downstream molecules, including kinases and transcription factors, which then trigger cellular events. In this chapter we provide a comprehensive summary of the biological functions of peptide hormones, focusing on how they mature and the ways in which they modulate plant functions. © 2015 Authors; published by Portland Press Limited.

  20. Designing Antibacterial Peptides with Enhanced Killing Kinetics

    Directory of Open Access Journals (Sweden)

    Faiza H. Waghu

    2018-02-01

    Full Text Available Antimicrobial peptides (AMPs are gaining attention as substitutes for antibiotics in order to combat the risk posed by multi-drug resistant pathogens. Several research groups are engaged in design of potent anti-infective agents using natural AMPs as templates. In this study, a library of peptides with high sequence similarity to Myeloid Antimicrobial Peptide (MAP family were screened using popular online prediction algorithms. These peptide variants were designed in a manner to retain the conserved residues within the MAP family. The prediction algorithms were found to effectively classify peptides based on their antimicrobial nature. In order to improve the activity of the identified peptides, molecular dynamics (MD simulations, using bilayer and micellar systems could be used to design and predict effect of residue substitution on membranes of microbial and mammalian cells. The inference from MD simulation studies well corroborated with the wet-lab observations indicating that MD-guided rational design could lead to discovery of potent AMPs. The effect of the residue substitution on membrane activity was studied in greater detail using killing kinetic analysis. Killing kinetics studies on Gram-positive, negative and human erythrocytes indicated that a single residue change has a drastic effect on the potency of AMPs. An interesting outcome was a switch from monophasic to biphasic death rate constant of Staphylococcus aureus due to a single residue mutation in the peptide.

  1. Potentiation of peptide receptor radionuclide therapy by the PARP inhibitor olaparib

    NARCIS (Netherlands)

    J. Nonnekens (Julie); M. van Kranenburg (Melissa); C.E.M.T. Beerens (Cecile); M. Suker (Mustafa); M. Doukas (Michael); C.H.J. van Eijck (Casper); M. de Jong (Marcel); D.C. van Gent (Dik)

    2016-01-01

    textabstractMetastases expressing tumor-specific receptors can be targeted and treated by binding of radiolabeled peptides (peptide receptor radionuclide therapy or PRRT). For example, patients with metastasized somatostatin receptor-positive neuroendocrine tumors (NETs) can be treated with

  2. False memories in social anxiety disorder

    Directory of Open Access Journals (Sweden)

    PRISCILA DE CAMARGO PALMA

    Full Text Available Abstract Background False memories are memories of events that never occurred or that occurred, but not exactly as we recall. Events with emotional content are subject to false memories production similar to neutral events. However, individual differences, such as the level of maladjustment and emotional instability characteristics of Social Anxiety Disorder (SAD, may interfere in the production of false memories. Objectives This study aimed to assess the effect of emotion in memory performance for an event witnessed by participants with and without SAD. Methods Participants were 61 young adults with SAD and 76 without any symptoms of SAD who were randomly assigned to watch a story with or without emotional arousal. Participants answered a subjective scale of emotion about the story and a recognition memory test. Results Participants with SAD recovered more true memories and more false memories for the non-emotional version compared to the emotional version of the story. Overall, participants with SAD produced fewer false memories compared to those without SAD. Discussion This finding suggests that social anxiety may have a significant impact on emotional memory accuracy, which may assist in the development and improvement of techniques for therapeutic intervention.

  3. Reducing false asystole alarms in intensive care.

    Science.gov (United States)

    Dekimpe, Remi; Heldt, Thomas

    2017-07-01

    High rates of false monitoring alarms in intensive care can desensitize staff and therefore pose a significant risk to patient safety. Like other critical arrhythmia alarms, asystole alarms require immediate attention by the care providers as a true asystole event can be acutely life threatening. Here, it is illustrated that most false asystole alarms can be attributed to poor signal quality, and we propose and evaluate an algorithm to identify data windows of poor signal quality and thereby help suppress false asystole alarms. The algorithm combines intuitive signal-quality features (degree of signal saturation and baseline wander) and information from other physiological signals that might be available. Algorithm training and testing was performed on the MIMIC II and 2015 PhysioNet/Computing in Cardiology Challenge databases, respectively. The algorithm achieved an alarm specificity of 81.0% and sensitivity of 95.4%, missing only one out of 22 true asystole alarms. On a separate neonatal data set, the algorithm was able to reject 89.7% (890 out of 992) of false asystole alarms while keeping all 22 true events. The results show that the false asystole alarm rate can be significantly reduced through basic signal quality evaluation.

  4. Semi-automated Biopanning of Bacterial Display Libraries for Peptide Affinity Reagent Discovery and Analysis of Resulting Isolates.

    Science.gov (United States)

    Sarkes, Deborah A; Jahnke, Justin P; Stratis-Cullum, Dimitra N

    2017-12-06

    Biopanning bacterial display libraries is a proven technique for peptide affinity reagent discovery for recognition of both biotic and abiotic targets. Peptide affinity reagents can be used for similar applications to antibodies, including sensing and therapeutics, but are more robust and able to perform in more extreme environments. Specific enrichment of peptide capture agents to a protein target of interest is enhanced using semi-automated sorting methods which improve binding and wash steps and therefore decrease the occurrence of false positive binders. A semi-automated sorting method is described herein for use with a commercial automated magnetic-activated cell sorting device with an unconstrained bacterial display sorting library expressing random 15-mer peptides. With slight modifications, these methods are extendable to other automated devices, other sorting libraries, and other organisms. A primary goal of this work is to provide a comprehensive methodology and expound the thought process applied in analyzing and minimizing the resulting pool of candidates. These techniques include analysis of on-cell binding using fluorescence-activated cell sorting (FACS), to assess affinity and specificity during sorting and in comparing individual candidates, and the analysis of peptide sequences to identify trends and consensus sequences for understanding and potentially improving the affinity to and specificity for the target of interest.

  5. Finding False Paths in Sequential Circuits

    Science.gov (United States)

    Matrosova, A. Yu.; Andreeva, V. V.; Chernyshov, S. V.; Rozhkova, S. V.; Kudin, D. V.

    2018-02-01

    Method of finding false paths in sequential circuits is developed. In contrast with heuristic approaches currently used abroad, the precise method based on applying operations on Reduced Ordered Binary Decision Diagrams (ROBDDs) extracted from the combinational part of a sequential controlling logic circuit is suggested. The method allows finding false paths when transfer sequence length is not more than the given value and obviates the necessity of investigation of combinational circuit equivalents of the given lengths. The possibilities of using of the developed method for more complicated circuits are discussed.

  6. False iliac artery aneurysm following renal transplantation

    DEFF Research Database (Denmark)

    Levi, N; Sønksen, Jens Otto Reimers; Schroeder, T V

    1999-01-01

    We report a very rare case of a false iliac artery aneurysm following renal transplantation. The patient was a 51-year-old women who presented with a painful 10 x 10 cm pulsating mass in her left iliac fossa. The patient had received a second cadaveric renal transplantation 5 years previously....... The graft never functioned and transplant nephrectomy was performed 2 weeks later. A CT-scanning showed a 10 x 10 cm large aneurysm arising from the left external iliac artery. At operation a large false aneurysm was identified arising from the original transplant anastomotic site. Due to the extent...

  7. Antimicrobial Peptides in Reptiles

    Science.gov (United States)

    van Hoek, Monique L.

    2014-01-01

    Reptiles are among the oldest known amniotes and are highly diverse in their morphology and ecological niches. These animals have an evolutionarily ancient innate-immune system that is of great interest to scientists trying to identify new and useful antimicrobial peptides. Significant work in the last decade in the fields of biochemistry, proteomics and genomics has begun to reveal the complexity of reptilian antimicrobial peptides. Here, the current knowledge about antimicrobial peptides in reptiles is reviewed, with specific examples in each of the four orders: Testudines (turtles and tortosises), Sphenodontia (tuataras), Squamata (snakes and lizards), and Crocodilia (crocodilans). Examples are presented of the major classes of antimicrobial peptides expressed by reptiles including defensins, cathelicidins, liver-expressed peptides (hepcidin and LEAP-2), lysozyme, crotamine, and others. Some of these peptides have been identified and tested for their antibacterial or antiviral activity; others are only predicted as possible genes from genomic sequencing. Bioinformatic analysis of the reptile genomes is presented, revealing many predicted candidate antimicrobial peptides genes across this diverse class. The study of how these ancient creatures use antimicrobial peptides within their innate immune systems may reveal new understandings of our mammalian innate immune system and may also provide new and powerful antimicrobial peptides as scaffolds for potential therapeutic development. PMID:24918867

  8. Peptide Antibiotics for ESKAPE Pathogens

    DEFF Research Database (Denmark)

    Thomsen, Thomas Thyge

    Multi-drug resistance to antibiotics represents a global health challenge that results in increased morbidity and mortality rates. The annual death-toll is >700.000 people world-wide, rising to ~10 million by 2050. New antibiotics are lacking, and few are under development as return on investment...... is considered poor compared to medicines for lifestyle diseases. According to the WHO we could be moving towards a post-antibiotic era in which previously treatable infections become fatal. Of special importance are multidrug resistant bacteria from the ESKAPE group (Enterococcus faecium, Staphylococcus aureus...... and toxicity by utilizing of the fruit fly Drosophila melanogaster as a whole animal model. This was carried out by testing of antimicrobial peptides targeting Gram-positive bacteria exemplified by the important human pathogen methicillin resistant S. aureus (MRSA). The peptide BP214 was developed from...

  9. Pluto behaving badly: false beliefs and their consequences.

    Science.gov (United States)

    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.

  10. False memories and memory confidence in borderline patients.

    Science.gov (United States)

    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.

  11. Halogenation dictates the architecture of amyloid peptide nanostructures.

    Science.gov (United States)

    Pizzi, Andrea; Pigliacelli, Claudia; Gori, Alessandro; Nonappa; Ikkala, Olli; Demitri, Nicola; Terraneo, Giancarlo; Castelletto, Valeria; Hamley, Ian W; Baldelli Bombelli, Francesca; Metrangolo, Pierangelo

    2017-07-20

    Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures.

  12. Improving sensitivity in proteome studies by analysis of false discovery rates for multiple search engines.

    Science.gov (United States)

    Jones, Andrew R; Siepen, Jennifer A; Hubbard, Simon J; Paton, Norman W

    2009-03-01

    LC-MS experiments can generate large quantities of data, for which a variety of database search engines are available to make peptide and protein identifications. Decoy databases are becoming widely used to place statistical confidence in result sets, allowing the false discovery rate (FDR) to be estimated. Different search engines produce different identification sets so employing more than one search engine could result in an increased number of peptides (and proteins) being identified, if an appropriate mechanism for combining data can be defined. We have developed a search engine independent score, based on FDR, which allows peptide identifications from different search engines to be combined, called the FDR Score. The results demonstrate that the observed FDR is significantly different when analysing the set of identifications made by all three search engines, by each pair of search engines or by a single search engine. Our algorithm assigns identifications to groups according to the set of search engines that have made the identification, and re-assigns the score (combined FDR Score). The combined FDR Score can differentiate between correct and incorrect peptide identifications with high accuracy, allowing on average 35% more peptide identifications to be made at a fixed FDR than using a single search engine.

  13. A Synchronization Account of False Recognition

    Science.gov (United States)

    Johns, Brendan T.; Jones, Michael N.; Mewhort, Douglas J. K.

    2012-01-01

    We describe a computational model to explain a variety of results in both standard and false recognition. A key attribute of the model is that it uses plausible semantic representations for words, built through exposure to a linguistic corpus. A study list is encoded in the model as a gist trace, similar to the proposal of fuzzy trace theory…

  14. Interrogation and false confessions: vulnerability factors.

    Science.gov (United States)

    Gudjonsson, G H

    This paper reviews the psychological factors that make some individuals susceptible to making a false confession of having committed a criminal offence. A number of 'vulnerability factors' are highlighted and it is emphasized that these need to be interpreted within the context of all circumstances surrounding the case.

  15. Power Factor Controller Avoids False Turnoff

    Science.gov (United States)

    Nola, F. J.

    1983-01-01

    Single-phase power-factor controller includes special inhibiting circuit to avoid false turnoff. If thyristor trigger signal occurs during flow of current from preceding half cycle, inhibiting signal delays application of trigger pulse until beginning of next current half cycle.

  16. Distance Sensitive Bloom Filters Without False Negatives

    DEFF Research Database (Denmark)

    Goswami, Mayank; Pagh, Rasmus; Silvestri, Francesco

    2017-01-01

    answers. Absence of false negatives is of critical importance in many applications of Bloom filters, so it is natural to ask if this can be also achieved in the distance sensitive setting. Our main contributions are upper and lower bounds (that are tight in several cases) for space usage in the distance...

  17. Disfluent presentations lead to the creation of more false memories.

    Directory of Open Access Journals (Sweden)

    Christopher A Sanchez

    Full Text Available 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.

  18. False memory and the associative network of happiness.

    Science.gov (United States)

    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.

  19. Discrete emotion-congruent false memories in the DRM paradigm.

    Science.gov (United States)

    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).

  20. Insulin C-peptide test

    Science.gov (United States)

    C-peptide ... the test depends on the reason for the C-peptide measurement. Ask your health care provider if ... C-peptide is measured to tell the difference between insulin the body produces and insulin someone injects ...

  1. Neural Network Target Identification System for False Alarm Reduction

    Science.gov (United States)

    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.

  2. [False memory syndrome: state of the art].

    Science.gov (United States)

    Nemets, Boris; Witztum, Eliezer; Kotler, Moshe

    2002-08-01

    The review describes the heated dispute on the present state of recovered traumatic memories. There are two main schools concerning the status of recovered memories of child abuse. One school believes in their authenticity unconditionally. Those who oppose the authenticity claim False Memory Syndrome's existence. They describe it as "a serious form of psychopathology characterized by strongly believed pseudomemories of childhood sexual abuse" and "condition in which a person's identity and interpersonal relationships are centered around a memory of traumatic experience which is objectively false but in which the person strongly believes". This review presents the allegations of both sides involved in the dispute, with updates of scientific and judicial references and relevant recommendations to care takers.

  3. Imagination can create false autobiographical memories.

    Science.gov (United States)

    Mazzoni, Giuliana; Memon, Amina

    2003-03-01

    Previous studies have shown that imagining an event can alter autobiographical beliefs. The current study examined whether it can also create false memories. One group of participants imagined a relatively frequent event and received information about an event that never occurs. A second group imagined the nonoccurring event and received information about the frequent event. One week before and again 1 week immediately after the manipulation, participants rated the likelihood that they had experienced each of the two critical events and a series of noncritical events, using the Life Events Inventory. During the last phase, participants were also asked to describe any memories they had for the events. For both events, imagination increased the number of memories reported, as well as beliefs about experiencing the event. These results indicate that imagination can induce false autobiographical memories.

  4. Underlying processes behind false perspective production

    Directory of Open Access Journals (Sweden)

    Antonio L. Manzanero

    2016-01-01

    Full Text Available This study aimed to determine the extent to which Reality Monitoring (RM content analysis can provide useful information when discriminating between actual versus false statements. Participants were instructed to either describe a traffic accident as eyewitness actual role or to describe the accident as a simulated victim. Data were analysed in terms of accuracy and quality, and were represented using high dimensional visualization (HDV. In Experiment 1 (between-participant design, participants made significantly more references to cognitive operations, more self-references and less changes in order when describing the event as simulated victim. In Experiment 2 (within-participants design participants also made significantly more references to cognitive operations and more self references when describing the event from the simulated victim as well as being less accurate, providing less irrelevant information and more evalúative comments. HDV graphics indicated that false statements differ holistically from actual ones.

  5. Constrained potential method for false vacuum decays

    International Nuclear Information System (INIS)

    Park, Jae-hyeon

    2010-11-01

    A procedure is reported for numerical analysis of false vacuum transition in a model with multiple scalar fields. It is a refined version of the approach by Konstandin and Huber. The alteration makes it possible to tackle a class of problems that was difficult or unsolvable with the original method, i.e. those with a distant or nonexistent true vacuum. An example with an unbounded-from-below direction is presented. (orig.)

  6. False Context Fear Memory in Rats

    Science.gov (United States)

    Bae, Sarah; Holmes, Nathan M.; Westbrook, R. Frederick

    2015-01-01

    Four experiments used rats to study false context fear memories. In Experiment 1, rats were pre-exposed to a distinctive chamber (context A) or to a control environment (context C), shocked after a delay in a second chamber (context B) and tested either in B or A. Rats pre-exposed to A froze just as much as control rats in B but more than control…

  7. False memories in Lewy-body disease.

    Science.gov (United States)

    Algarabel, Salvador; Pitarque, Alfonso; Sales, Alicia; Meléndez, Juan Carlos; Escudero, Joaquín

    2015-12-01

    Recently, de Boysson, Belleville, Phillips et al. (2011) found that patients with Lewy-body disease (LBD) showed significantly lower rates of false memories than healthy controls, using the Deese-Roediger-McDermott (DRM) experimental procedure. Given that this result could be explained by the practically null rate of true recognition in the LBD group (0.09), we decided to replicate the study by de Boysson et al. (2011), but including a new condition that would maximize the true recognition rate (and analyze its effect on the rate of false memories). Specifically, in a DRM experiment, we manipulated (within subjects) two study and recognition conditions: in the "immediate" condition, both the LBD patients and the control group of healthy older people received a different recognition test after each study list (containing twelve words associated with a non-presented critical word), while in the "delayed" condition (similar to the one in de Boysson et al., 2011), the participants received the entire series of study lists and then took only one recognition test. The results showed that, in both samples, the "immediate" condition produced higher corrected rates of both true and false recognition than the "delayed" condition, although they were both lower in the LBD patients, which shows that these patients are capable of encoding and recognizing the general similitude underlying information (gist memory) in the right conditions. © 2015 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  8. False confessions, expert testimony, and admissibility.

    Science.gov (United States)

    Watson, Clarence; Weiss, Kenneth J; Pouncey, Claire

    2010-01-01

    The confession of a criminal defendant serves as a prosecutor's most compelling piece of evidence during trial. Courts must preserve a defendant's constitutional right to a fair trial while upholding the judicial interests of presenting competent and reliable evidence to the jury. When a defendant seeks to challenge the validity of that confession through expert testimony, the prosecution often contests the admissibility of the expert's opinion. Depending on the content and methodology of the expert's opinion, testimony addressing the phenomenon of false confessions may or may not be admissible. This article outlines the scientific and epistemological bases of expert testimony on false confession, notes the obstacles facing its admissibility, and provides guidance to the expert in formulating opinions that will reach the judge or jury. We review the 2006 New Jersey Superior Court decision in State of New Jersey v. George King to illustrate what is involved in the admissibility of false-confession testimony and use the case as a starting point in developing a best-practice approach to working in this area.

  9. Imaging of metastatic melanoma utilising a technetium-99m labelled RGD-containing synthetic peptide

    Energy Technology Data Exchange (ETDEWEB)

    Sivolapenko, G.B. [Encephalos Research and Therapeutic Inst., Athens (Greece)]|[Agii Anargiri Cancer Hospital, Athens (Greece); Skarlos, D. [Agii Anargiri Cancer Hospital, Athens (Greece); Pectasides, D. [Metaxa Cancer Hospital, Athens (Greece); Stathopoulou, E.; Milonakis, A.; Sirmalis, G.; Konstantinides, K. [Encephalos Research and Therapeutic Inst., Athens (Greece); Stuttle, A.; Courtenay-Luck, N.S.; Epenetos, A.A. [Antisoma plc., London (United Kingdom)

    1998-10-01

    Integrins are cell-surface glycoproteins found in different forms on all cells except erythrocytes. Integrins bind to cell adhesion molecules and to proteins found in the extracellular matrix. A tripeptidic sequence Arg-Gly-Asp (RGD) is often the primary site of recognition by integrins which are expressed on tumour cells and are responsible for tumour invasion and metastasis. A synthetic decapeptide designated {alpha}P2 containing two RGD sequences radiolabelled with technetium-99m was used to image malignant melanoma in vivo. Fourteen patients previously diagnosed with metastatic melanoma underwent gamma camera imaging 20-180 min following intravenous administration of the radiolabelled synthetic decapeptide {alpha}P2. Six out of eight (6/8) of the lymph node metastases (75%) and all other neoplastic sites (11 sites) were successfully imaged, with the exception of three sites in the mediastinal area which were not positively imaged. In two cases there was false positive uptake in the rounded pigmented areolar/nipple area. In three cases (seven sites) the peptide scan confirmed the absence of disease in suspected lesions (true-negative). The synthetic peptide was rapidly removed from the circulation by filtration through the kidneys and excretion in the urine. No toxicity or adverse events were recorded. Radiolabelled {alpha}P2 peptide, which binds specifically to adhesion molecules on tumours, can be used for the in vivo detection of neoplastic metastases. (orig.) With 5 figs., 2 tabs., 24 refs.

  10. Exploring the chemical space of quorum sensing peptides.

    Science.gov (United States)

    Wynendaele, Evelien; Gevaert, Bert; Stalmans, Sofie; Verbeke, Frederick; De Spiegeleer, Bart

    2015-09-01

    Quorum sensing peptides are signalling molecules that are produced by mainly gram-positive bacteria. These peptides can exert different effects, ranging from intra- and interspecies bacterial virulence to bacterial-host interactions. To better comprehend these functional differences, we explored their chemical space, bacterial species distribution and receptor-binding properties using multivariate data analyses, with information obtained from the Quorumpeps database. The quorum sensing peptides can be categorized into three main clusters, which, in turn, can be divided into several subclusters: the classification is based on characteristic chemical properties, including peptide size/compactness, hydrophilicity/lipophilicity, cyclization and the presence of (unnatural) S-containing and aromatic amino acids. Most of the bacterial species synthesize peptides located into one cluster. However, some Streptococcus, Stapylococcus, Clostridium, Bacillus and Lactobacillus species produce peptides that are distributed over more than one cluster, with the quorum sensing peptides of Bacillus subtilis even occupying the total peptide space. The AgrC, FsrC and LamC receptors are only activated by cyclic (thio)lacton or lactam quorum sensing peptides, while the lipophilic isoprenyl-modified peptides solely bind the ComP receptor in Bacillus species. © 2015 Wiley Periodicals, Inc.

  11. Characterization of Selective Antibacterial Peptides by Polarity Index

    Directory of Open Access Journals (Sweden)

    C. Polanco

    2012-01-01

    Full Text Available In the recent decades, antibacterial peptides have occupied a strategic position for pharmaceutical drug applications and became subject of intense research activities since they are used to strengthen the immune system of all living organisms by protecting them from pathogenic bacteria. This work proposes a simple and easy statistical/computational method through a peptide polarity index measure by which an antibacterial peptide subgroup can be efficiently identified, that is, characterized by a high toxicity to bacterial membranes but presents a low toxicity to mammal cells. These peptides also have the feature not to adopt to an alpha-helicoidal structure in aqueous solution. The double-blind test carried out to the whole Antimicrobial Peptide Database (November 2011 showed an accuracy of 90% applying the polarity index method for the identification of such antibacterial peptide groups.

  12. Maltreatment increases spontaneous false memories but decreases suggestion-induced false memories in children.

    Science.gov (United States)

    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.

  13. Filing false vice reports: Distinguishing true from false allegations of rape

    NARCIS (Netherlands)

    de Zutter, A.; Horselenberg, R.; van Koppen, P.J.

    2017-01-01

    False allegations constitute a problem since they may cause harm. To study the difference between true and false allegations we used a quasi-experimental approach. In the control condition likely true allegations were retrieved from criminal files. The victims, all female, were between the ages of

  14. Beware of false green power marketers

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1997-06-01

    A warning was sounded to make people aware of false marketers of `green power`. These are companies that purchase excess power from existing sources, including nuclear, coal and large-scale hydro, and resell it at inflated prices to unsuspecting consumers. These consumers believe that they are buying power from renewable sources. With large amounts of money at stake, there are many new opportunities for unscrupulous companies to take advantage of the good intentions of environmentally conscious customers. Therefore, before making a commitment to purchase power from companies that claim to be enviro-friendly, it is important to check out the facts and be aware of how the industry works.

  15. False vacuum decay in gauge theory

    Science.gov (United States)

    Endo, Motoi; Moroi, Takeo; Nojiri, Mihoko M.; Shoji, Yutaro

    2017-11-01

    The decay rate of a false vacuum is studied in gauge theory, paying particular attention to its gauge invariance. Although the decay rate should not depend on the gauge parameter ξ according to the Nielsen identity, the gauge invariance of the result of a perturbative calculation has not been clearly shown. We give a prescription to perform a one-loop calculation of the decay rate, with which a manifestly gauge-invariant expression of the decay rate is obtained. We also discuss the renormalization necessary to make the result finite, and show that the decay rate is independent of the gauge parameter even after the renormalization.

  16. A peptide-binding assay for the disease-associated HLA-DQ8 molecule

    DEFF Research Database (Denmark)

    Straumfors, A; Johansen, B H; Vartdal, F

    1998-01-01

    The study of peptide binding to HLA class II molecules has mostly concentrated on DR molecules. Since many autoimmune diseases show a primary association to particular DQ molecules rather than DR molecules, it is also important to study the peptide-binding properties of DQ molecules. Here we report...... a biochemical peptide-binding assay for the type I diabetes-associated DQ8, i.e. DQ (alpha1*0301, beta1*0302), molecule. Affinity-purified DQ8 molecules were tested in peptide-binding assays using a radiolabelled influenza haemagglutinin (Ha) peptide encompassing positions 255-271(Y) as an indicator peptide...... of 43 peptides of different lengths and sequences. The DQ8 molecules showed a different pattern of peptide binding compared to a previously studied DQ2 molecule. Peptides derived from thyroid peroxidase, HLA-DQ(alpha1*0301), HLA-DQ(alpha1*0302), retinol receptor and p21ras were among the high...

  17. Descriptors for antimicrobial peptides

    DEFF Research Database (Denmark)

    Jenssen, Håvard

    2011-01-01

    Introduction: A frightening increase in the number of isolated multidrug resistant bacterial strains linked to the decline in novel antimicrobial drugs entering the market is a great cause for concern. Cationic antimicrobial peptides (AMPs) have lately been introduced as a potential new class...... of antimicrobial drugs, and computational methods utilizing molecular descriptors can significantly accelerate the development of new peptide drug candidates. Areas covered: This paper gives a broad overview of peptide and amino-acid scale descriptors available for AMP modeling and highlights which...

  18. Sleep deprivation increases formation of false memory.

    Science.gov (United States)

    Lo, June C; Chong, Pearlynne L H; Ganesan, Shankari; Leong, Ruth L F; Chee, Michael W L

    2016-12-01

    Retrieving false information can have serious consequences. Sleep is important for memory, but voluntary sleep curtailment is becoming more rampant. Here, the misinformation paradigm was used to investigate false memory formation after 1 night of total sleep deprivation in healthy young adults (N = 58, mean age ± SD = 22.10 ± 1.60 years; 29 males), and 7 nights of partial sleep deprivation (5 h sleep opportunity) in these young adults and healthy adolescents (N = 54, mean age ± SD = 16.67 ± 1.03 years; 25 males). In both age groups, sleep-deprived individuals were more likely than well-rested persons to incorporate misleading post-event information into their responses during memory retrieval (P sleep in optimal cognitive functioning, reveal the vulnerability of adolescents' memory during sleep curtailment, and suggest the need to assess eyewitnesses' sleep history after encountering misleading information. © 2016 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.

  19. Biased selection of propagation-related TUPs from phage display peptide libraries.

    Science.gov (United States)

    Zade, Hesam Motaleb; Keshavarz, Reihaneh; Shekarabi, Hosna Sadat Zahed; Bakhshinejad, Babak

    2017-08-01

    Phage display is rapidly advancing as a screening strategy in drug discovery and drug delivery. Phage-encoded combinatorial peptide libraries can be screened through the affinity selection procedure of biopanning to find pharmaceutically relevant cell-specific ligands. However, the unwanted enrichment of target-unrelated peptides (TUPs) with no true affinity for the target presents an important barrier to the successful screening of phage display libraries. Propagation-related TUPs (Pr-TUPs) are an emerging but less-studied category of phage display-derived false-positive hits that are displayed on the surface of clones with faster propagation rates. Despite long regarded as an unbiased selection system, accumulating evidence suggests that biopanning may create biological bias toward selection of phage clones with certain displayed peptides. This bias can be dependent on or independent of the displayed sequence and may act as a major driving force for the isolation of fast-growing clones. Sequence-dependent bias is reflected by censorship or over-representation of some amino acids in the displayed peptide and sequence-independent bias is derived from either point mutations or rare recombination events occurring in the phage genome. It is of utmost interest to clean biopanning data by identifying and removing Pr-TUPs. Experimental and bioinformatic approaches can be exploited for Pr-TUP discovery. With no doubt, obtaining deeper insight into how Pr-TUPs emerge during biopanning and how they could be detected provides a basis for using cell-targeting peptides isolated from phage display screening in the development of disease-specific diagnostic and therapeutic platforms.

  20. Mapping the Real and the False

    DEFF Research Database (Denmark)

    Kuever, Erika

    2014-01-01

    brands establish themselves in the Chinese market now threaten the capability of all brands to gain and retain the trust of consumers. Originality/value -- By explaining how new calculations of value are being produced under glocalized regimes of manufacture and distribution, this research makes......Purpose -- To show that Chinese consumers are constantly redefining and revaluing goods along the axes of the real and the false, with little regard for legal definitions of brand authenticity or “fakeness.” Findings -- In their everyday consumption practices and navigation of a complex and often...... dangerous marketplace, Chinese consumers categorize products based on their perceived “truth.” The paper introduces a typology that describes these local categories and explains their utility for consumers. Practical/social implications -- This paper explains how the same globalizing processes that helped...

  1. Remembering, imagining, false memories & personal meanings.

    Science.gov (United States)

    Conway, Martin A; Loveday, Catherine

    2015-05-01

    The Self-Memory System encompasses the working self, autobiographical memory and episodic memory. Specific autobiographical memories are patterns of activation over knowledge structures in autobiographical and episodic memory brought about by the activating effect of cues. The working self can elaborate cues based on the knowledge they initially activate and so control the construction of memories of the past and the future. It is proposed that such construction takes place in the remembering-imagining system - a window of highly accessible recent memories and simulations of near future events. How this malfunctions in various disorders is considered as are the implication of what we term the modern view of human memory for notions of memory accuracy. We show how all memories are to some degree false and that the main role of memories lies in generating personal meanings. Copyright © 2014. Published by Elsevier Inc.

  2. True or False Customer Engagement Behaviour

    DEFF Research Database (Denmark)

    Haurum, Helle; Beckmann, Suzanne C.

    2014-01-01

    Customers’ engagement behaviours are considered an important source of value to the company. So far, the discussion has mainly been conceptual and focused on the company’s perspective. By adopting the customer’s perspective we investigated how customers perceive their service relationship...... encounters with a company, using in-depth interviews. We found the following key factors driving and explaining customers’ engagement behaviours: (1) transactions matter and inconsistent engagement behaviours are a reality, (2) mundane products and services are still highly relevant for customers, and (3......) different degrees of customer experience alignment with services and products exist. Moreover, the distinction between true and false engagement behaviours we suggest indeed is relevant and we could establish their mediating capabilities....

  3. False discovery rates: a new deal.

    Science.gov (United States)

    Stephens, Matthew

    2017-04-01

    We introduce a new Empirical Bayes approach for large-scale hypothesis testing, including estimating false discovery rates (FDRs), and effect sizes. This approach has two key differences from existing approaches to FDR analysis. First, it assumes that the distribution of the actual (unobserved) effects is unimodal, with a mode at 0. This "unimodal assumption" (UA), although natural in many contexts, is not usually incorporated into standard FDR analysis, and we demonstrate how incorporating it brings many benefits. Specifically, the UA facilitates efficient and robust computation-estimating the unimodal distribution involves solving a simple convex optimization problem-and enables more accurate inferences provided that it holds. Second, the method takes as its input two numbers for each test (an effect size estimate and corresponding standard error), rather than the one number usually used ($p$ value or $z$ score). When available, using two numbers instead of one helps account for variation in measurement precision across tests. It also facilitates estimation of effects, and unlike standard FDR methods, our approach provides interval estimates (credible regions) for each effect in addition to measures of significance. To provide a bridge between interval estimates and significance measures, we introduce the term "local false sign rate" to refer to the probability of getting the sign of an effect wrong and argue that it is a superior measure of significance than the local FDR because it is both more generally applicable and can be more robustly estimated. Our methods are implemented in an R package ashr available from http://github.com/stephens999/ashr. © The Author 2016. Published by Oxford University Press.

  4. Tumor penetrating peptides

    Directory of Open Access Journals (Sweden)

    Tambet eTeesalu

    2013-08-01

    Full Text Available Tumor-homing peptides can be used to deliver drugs into tumors. Phage library screening in live mice has recently identified homing peptides that specifically recognize the endothelium of tumor vessels, extravasate, and penetrate deep into the extravascular tumor tissue. The prototypic peptide of this class, iRGD (CRGDKGPDC, contains the integrin-binding RGD motif. RGD mediates tumor homing through binding to αv integrins, which are selectively expressed on various cells in tumors, including tumor endothelial cells. The tumor-penetrating properties of iRGD are mediated by a second sequence motif, R/KXXR/K. This C-end Rule (or CendR motif is active only when the second basic residue is exposed at the C-terminus of the peptide. Proteolytic processing of iRGD in tumors activates the cryptic CendR motif, which then binds to neuropilin-1 activating an endocytic bulk transport pathway through tumor tissue. Phage screening has also yielded tumor-penetrating peptides that function like iRGD in activating the CendR pathway, but bind to a different primary receptor. Moreover, novel tumor-homing peptides can be constructed from tumor-homing motifs, CendR elements and protease cleavage sites. Pathologies other than tumors can be targeted with tissue-penetrating peptides, and the primary receptor can also be a vascular zip code of a normal tissue. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. The tumor-penetrating peptides are capable of taking a payload deep into tumor tissue in mice, and they also penetrate into human tumors ex vivo. Targeting with these peptides specifically increases the accumulation in tumors of a variety of drugs and contrast agents, such as doxorubicin, antibodies and nanoparticle-based compounds. Remarkably the drug to be targeted does not have to be coupled to the peptide; the bulk transport system activated by the peptide sweeps along any compound that is

  5. Tumor-Penetrating Peptides

    Science.gov (United States)

    Teesalu, Tambet; Sugahara, Kazuki N.; Ruoslahti, Erkki

    2013-01-01

    Tumor-homing peptides can be used to deliver drugs into tumors. Phage library screening in live mice has recently identified homing peptides that specifically recognize the endothelium of tumor vessels, extravasate, and penetrate deep into the extravascular tumor tissue. The prototypic peptide of this class, iRGD (CRGDKGPDC), contains the integrin-binding RGD motif. RGD mediates tumor-homing through binding to αv integrins, which are selectively expressed on various cells in tumors, including tumor endothelial cells. The tumor-penetrating properties of iRGD are mediated by a second sequence motif, R/KXXR/K. This C-end Rule (or CendR) motif is active only when the second basic residue is exposed at the C-terminus of the peptide. Proteolytic processing of iRGD in tumors activates the cryptic CendR motif, which then binds to neuropilin-1 activating an endocytic bulk transport pathway through tumor tissue. Phage screening has also yielded tumor-penetrating peptides that function like iRGD in activating the CendR pathway, but bind to a different primary receptor. Moreover, novel tumor-homing peptides can be constructed from tumor-homing motifs, CendR elements and protease cleavage sites. Pathologies other than tumors can be targeted with tissue-penetrating peptides, and the primary receptor can also be a vascular “zip code” of a normal tissue. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. The tumor-penetrating peptides are capable of taking a payload deep into tumor tissue in mice, and they also penetrate into human tumors ex vivo. Targeting with these peptides specifically increases the accumulation in tumors of a variety of drugs and contrast agents, such as doxorubicin, antibodies, and nanoparticle-based compounds. Remarkably the drug to be targeted does not have to be coupled to the peptide; the bulk transport system activated by the peptide sweeps along any compound that is present in the

  6. Novel Endogenous Antimicrobial Peptides

    OpenAIRE

    Nordahl, Emma

    2009-01-01

    Antimicrobial peptides serve as a first line of defence against invading microorganisms and are an essential part of our fast innate immune system. They are ancient molecules found in all classes of life. Antimicrobial peptides rapidly kill a broad spectrum of microbes and are immunomodulatory, i.e. having additional actions influencing inflammation and other innate immune responses. Results presented in this thesis demonstrate that proteases of common human pathogens degrade and inactivate t...

  7. Identification of binding peptides of the ADAM15 disintegrin domain ...

    Indian Academy of Sciences (India)

    Madhsudhan

    Karkkainen et al. 2006). In this study, the recombinant ADAM15 disintegrin domain (RADD) was expressed in E. coli, and 4 specific binding peptides of RADD were obtained by positive panning and subtractive selection using a phage display 12-mer.

  8. Affective false memories in Dementia of Alzheimer's Type.

    Science.gov (United States)

    Fairfield, Beth; Colangelo, Mirco; Mammarella, Nicola; Di Domenico, Alberto; Cornoldi, Cesare

    2017-03-01

    This study examined the production of inferential false memories for complex pictorial stimuli and the implications of affective content in Alzheimer's disease (AD). A group of 24 AD patients and a group of 24 healthy older adults studied a sequence of pictures depicting stories that included positive, negative or neutral consequences of an unseen action, and then completed an old-new picture recognition test. The number of causal errors was higher in healthy older adults compared to AD patients but affective content attenuated the effect. Causal errors increased in AD patients when stories included affective (positive or negative) outcomes. In addition, negative content produced a larger number of errors than positive content across groups. This data confirms that although memory processing is poorer in AD, it is sensitive to affective content. Accordingly, the nature of affective false memory errors suggest the need to consider the use of affective information in the development of new cognitive training procedures. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  9. Adaptive false memory: Imagining future scenarios increases false memories in the DRM paradigm.

    Science.gov (United States)

    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.

  10. E-commerce Review System to Detect False Reviews.

    Science.gov (United States)

    Kolhar, Manjur

    2017-08-15

    E-commerce sites have been doing profitable business since their induction in high-speed and secured networks. Moreover, they continue to influence consumers through various methods. One of the most effective methods is the e-commerce review rating system, in which consumers provide review ratings for the products used. However, almost all e-commerce review rating systems are unable to provide cumulative review ratings. Furthermore, review ratings are influenced by positive and negative malicious feedback ratings, collectively called false reviews. In this paper, we proposed an e-commerce review system framework developed using the cumulative sum method to detect and remove malicious review ratings.

  11. Cationic Antimicrobial Peptides Inactivate Shiga Toxin-Encoding Bacteriophages

    Directory of Open Access Journals (Sweden)

    Manuel E. Del Cogliano

    2017-12-01

    Full Text Available Shiga toxin (Stx is the principal virulence factor during Shiga toxin-producing Escherichia coli (STEC infections. We have previously reported the inactivation of bacteriophage encoding Stx after treatment with chitosan, a linear polysaccharide polymer with cationic properties. Cationic antimicrobial peptides (cAMPs are short linear aminoacidic sequences, with a positive net charge, which display bactericidal or bacteriostatic activity against a wide range of bacterial species. They are promising novel antibiotics since they have shown bactericidal effects against multiresistant bacteria. To evaluate whether cationic properties are responsible for bacteriophage inactivation, we tested seven cationic peptides with proven antimicrobial activity as anti-bacteriophage agents, and one random sequence cationic peptide with no antimicrobial activity as a control. We observed bacteriophage inactivation after incubation with five cAMPs, but no inactivating activity was observed with the random sequence cationic peptide or with the non-alpha helical cAMP Omiganan. Finally, to confirm peptide-bacteriophage interaction, zeta potential was analyzed by following changes on bacteriophage surface charges after peptide incubation. According to our results we could propose that: (1 direct interaction of peptides with phage is a necessary step for bacteriophage inactivation, (2 cationic properties are necessary but not sufficient for bacteriophage inactivation, and (3 inactivation by cationic peptides could be sequence (or structure specific. Overall our data suggest that these peptides could be considered a new family of molecules potentially useful to decrease bacteriophage replication and Stx expression.

  12. Peptide inhibition of human cytomegalovirus infection

    Directory of Open Access Journals (Sweden)

    Morris Cindy A

    2011-02-01

    Full Text Available Abstract Background Human cytomegalovirus (HCMV is the most prevalent congenital viral infection in the United States and Europe causing significant morbidity and mortality to both mother and child. HCMV is also an opportunistic pathogen in immunocompromised individuals, including human immunodeficiency virus (HIV- infected patients with AIDS, and solid organ and allogeneic stem cell transplantation recipients. Current treatments for HCMV-associated diseases are insufficient due to the emergence of drug-induced resistance and cytotoxicity, necessitating novel approaches to limit HCMV infection. The aim of this study was to develop therapeutic peptides targeting glycoprotein B (gB, a major glycoprotein of HCMV that is highly conserved across the Herpesviridae family, that specifically inhibit fusion of the viral envelope with the host cell membrane preventing HCMV entry and infection. Results Using the Wimley-White Interfacial Hydrophobicity Scale (WWIHS, several regions within gB were identified that display a high potential to interact with lipid bilayers of cell membranes and hydrophobic surfaces within proteins. The ability of synthetic peptides analogous to WWIHS-positive sequences of HCMV gB to inhibit viral infectivity was evaluated. Human foreskin fibroblasts (HFF were infected with the Towne-GFP strain of HCMV (0.5 MOI, preincubated with peptides at a range of concentrations (78 nm to 100 μM, and GFP-positive cells were visualized 48 hours post-infection by fluorescence microscopy and analyzed quantitatively by flow cytometry. Peptides that inhibited HCMV infection demonstrated different inhibitory concentration curves indicating that each peptide possesses distinct biophysical properties. Peptide 174-200 showed 80% inhibition of viral infection at a concentration of 100 μM, and 51% and 62% inhibition at concentrations of 5 μM and 2.5 μM, respectively. Peptide 233-263 inhibited infection by 97% and 92% at concentrations of 100

  13. Deep Hole in 'Clovis' (False Color)

    Science.gov (United States)

    2004-01-01

    At a rock called 'Clovis,' the rock abrasion tool on NASA's Mars Exploration Rover Spirit cut a 9-millimeter (0.35-inch) hole during the rover's 216th martian day, or sol (Aug. 11, 2004). The hole is the deepest drilled in a rock on Mars so far. This false color view was made from images taken by Spirit's panoramic camera on sol 226 (Aug. 21, 2004) at around 12:50 p.m. local true solar time -- early afternoon in Gusev Crater on Mars. To the right is a 'brush flower' of circles produced by scrubbing the surface of the rock with the abrasion tool's wire brush. Scientists used rover's Moessbauer spectrometer and alpha particle X-ray spectrometer to look for iron-bearing minerals and determine the elemental chemical composition of the rock. This composite combines images taken with the camera's 750-, 530-, and 430-nanometer filters. The grayish-blue hue in this image suggests that the interior of the rock contains iron minerals that are less oxidized than minerals on the surface. The diameter of the hole cut into the rock is 4.5 centimeters (1.8 inches).

  14. Locality-sensitive Hashing without False Negatives

    DEFF Research Database (Denmark)

    Pagh, Rasmus

    2016-01-01

    We consider a new construction of locality-sensitive hash functions for Hamming space that is covering in the sense that is it guaranteed to produce a collision for every pair of vectors within a given radius r. The construction is efficient in the sense that the expected number of hash collisions......(n)/k, where n is the number of points in the data set and k ∊ N, and differs from it by at most a factor ln(4) in the exponent for general values of cr. As a consequence, LSH-based similarity search in Hamming space can avoid the problem of false negatives at little or no cost in efficiency. Read More: http...... between vectors at distance cr, for a given c > 1, comes close to that of the best possible data independent LSH without the covering guarantee, namely, the seminal LSH construction of Indyk and Motwani (FOCS ′98). The efficiency of the new construction essentially matches their bound if cr = log...

  15. Accurate prediction of peptide binding sites on protein surfaces.

    Directory of Open Access Journals (Sweden)

    Evangelia Petsalaki

    2009-03-01

    Full Text Available Many important protein-protein interactions are mediated by the binding of a short peptide stretch in one protein to a large globular segment in another. Recent efforts have provided hundreds of examples of new peptides binding to proteins for which a three-dimensional structure is available (either known experimentally or readily modeled but where no structure of the protein-peptide complex is known. To address this gap, we present an approach that can accurately predict peptide binding sites on protein surfaces. For peptides known to bind a particular protein, the method predicts binding sites with great accuracy, and the specificity of the approach means that it can also be used to predict whether or not a putative or predicted peptide partner will bind. We used known protein-peptide complexes to derive preferences, in the form of spatial position specific scoring matrices, which describe the binding-site environment in globular proteins for each type of amino acid in bound peptides. We then scan the surface of a putative binding protein for sites for each of the amino acids present in a peptide partner and search for combinations of high-scoring amino acid sites that satisfy constraints deduced from the peptide sequence. The method performed well in a benchmark and largely agreed with experimental data mapping binding sites for several recently discovered interactions mediated by peptides, including RG-rich proteins with SMN domains, Epstein-Barr virus LMP1 with TRADD domains, DBC1 with Sir2, and the Ago hook with Argonaute PIWI domain. The method, and associated statistics, is an excellent tool for predicting and studying binding sites for newly discovered peptides mediating critical events in biology.

  16. Proinsulin C-peptide interferes with insulin fibril formation

    International Nuclear Information System (INIS)

    Landreh, Michael; Stukenborg, Jan-Bernd; Willander, Hanna; Söder, Olle; Johansson, Jan; Jörnvall, Hans

    2012-01-01

    Highlights: ► Insulin and C-peptide can interact under insulin fibril forming conditions. ► C-peptide is incorporated into insulin aggregates and alters aggregation lag time. ► C-peptide changes insulin fibril morphology and affects backbone accessibility. ► C-peptide may be a regulator of fibril formation by β-cell granule proteins. -- Abstract: Insulin aggregation can prevent rapid insulin uptake and cause localized amyloidosis in the treatment of type-1 diabetes. In this study, we investigated the effect of C-peptide, the 31-residue peptide cleaved from proinsulin, on insulin fibrillation at optimal conditions for fibrillation. This is at low pH and high concentration, when the fibrils formed are regular and extended. We report that C-peptide then modulates the insulin aggregation lag time and profoundly changes the fibril appearance, to rounded clumps of short fibrils, which, however, still are Thioflavine T-positive. Electrospray ionization mass spectrometry also indicates that C-peptide interacts with aggregating insulin and is incorporated into the aggregates. Hydrogen/deuterium exchange mass spectrometry further reveals reduced backbone accessibility in insulin aggregates formed in the presence of C-peptide. Combined, these effects are similar to those of C-peptide on islet amyloid polypeptide fibrillation and suggest that C-peptide has a general ability to interact with amyloidogenic proteins from pancreatic β-cell granules. Considering the concentrations, these peptide interactions should be relevant also during physiological secretion, and even so at special sites post-secretory or under insulin treatment conditions in vivo.

  17. Evaluation of dermal wound healing activity of synthetic peptide SVVYGLR.

    Science.gov (United States)

    Uchinaka, Ayako; Kawaguchi, Naomasa; Ban, Tsuyoshi; Hamada, Yoshinosuke; Mori, Seiji; Maeno, Yoshitaka; Sawa, Yoshiki; Nagata, Kohzo; Yamamoto, Hirofumi

    2017-09-23

    SVVYGLR peptide (SV peptide) is a 7-amino-acid sequence with angiogenic properties that is derived from osteopontin in the extracellular matrix and promotes differentiation of fibroblasts to myofibroblast-like cells and the production of collagen type Ⅲ by cardiac fibroblasts. However, the effects of SV peptide on dermal cells and tissue are unknown. In this study, we evaluated the effects of this peptide in a rat model of dermal wound healing. The synthetic SV peptide was added to dermal fibroblasts or keratinocytes, and their cellular motility was evaluated. In an in vivo wound healing exeriment, male rats aged 8 weeks were randomly assigned to the SV peptide treatment, non-treated control, or phosphate-buffered saline (PBS) groups. Wound healing was assessed by its repair rate and histological features. Scratch assay and cell migration assays using the Chemotaxicell method showed that SV peptide significantly promoted the cell migration in both fibroblasts and keratinocytes. In contrast the proliferation potency of these cells was not affected by SV peptide. In the rat model, wound healing progressed faster in the SV peptide-treated group than in the control and PBS groups. The histopathological analyses showed that the SV peptide treatment stimulated the migration of fibroblasts to the wound area and increased the number of myofibroblasts. Immunohistochemical staining showed a marked increase of von Willebland factor-positive neomicrovessels in the SV peptide-treated group. In conclusion, SV peptide has a beneficial function to promote wound healing by stimulating granulation via stimulating angiogenesis, cell migration, and the myofibroblastic differentiation of fibroblasts. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Anisotropic Membrane Curvature Sensing by Amphipathic Peptides.

    Science.gov (United States)

    Gómez-Llobregat, Jordi; Elías-Wolff, Federico; Lindén, Martin

    2016-01-05

    Many proteins and peptides have an intrinsic capacity to sense and induce membrane curvature, and play crucial roles for organizing and remodeling cell membranes. However, the molecular driving forces behind these processes are not well understood. Here, we describe an approach to study curvature sensing by simulating the interactions of single molecules with a buckled lipid bilayer. We analyze three amphipathic antimicrobial peptides, a class of membrane-associated molecules that specifically target and destabilize bacterial membranes, and find qualitatively different sensing characteristics that would be difficult to resolve with other methods. Our findings provide evidence for direction-dependent curvature sensing mechanisms in amphipathic peptides and challenge existing theories of hydrophobic insertion. The buckling approach is generally applicable to a wide range of curvature-sensing molecules, and our results provide strong motivation to develop new experimental methods to track position and orientation of membrane proteins. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  19. Label-free peptide profiling of Orbitrap™ full mass spectra

    Directory of Open Access Journals (Sweden)

    Titulaer Mark K

    2011-01-01

    Orbitrap™ files can be increased by using more MS1 peptide profiling applications, including Peptrix, since it appears from the comparison of Peptrix with the other applications that all software packages have likely a high false negative rate of low intensity peptide peaks (missing peptides.

  20. Label-free peptide profiling of Orbitrap™ full mass spectra.

    Science.gov (United States)

    Titulaer, Mark K; de Costa, Dominique; Stingl, Christoph; Dekker, Lennard J; Sillevis Smitt, Peter Ae; Luider, Theo M

    2011-01-27

    profiling applications, including Peptrix, since it appears from the comparison of Peptrix with the other applications that all software packages have likely a high false negative rate of low intensity peptide peaks (missing peptides).

  1. Cartilage oligomeric matrix protein associates differentially with erosions and synovitis and has a different temporal course in cyclic citrullinated peptide antibody (anti-CCP)-positive versus anti-CCP-negative early rheumatoid arthritis

    DEFF Research Database (Denmark)

    Christensen, Anne F; Lindegaard, Hanne; Hørslev-Petersen, Kim

    2011-01-01

    -suppressive effect. We aimed to compare circulating cartilage oligomeric matrix protein (COMP), a marker of cartilage turnover, in untreated anti-CCP-positive and anti-CCP-negative RA, and to study the temporal pattern of COMP through 4 years of treatment, including the relationship to imaging and clinical findings.......048). In anti-CCP-positive patients, COMP exhibited a parabolic course over 4 years, while COMP in anti-CCP-negative patients had an almost linear course. In anti-CCP-positive patients, COMP was associated with MRI edema and erosion score, while COMP was correlated with synovitis score in anti...

  2. Granin-derived peptides.

    Science.gov (United States)

    Troger, Josef; Theurl, Markus; Kirchmair, Rudolf; Pasqua, Teresa; Tota, Bruno; Angelone, Tommaso; Cerra, Maria C; Nowosielski, Yvonne; Mätzler, Raphaela; Troger, Jasmin; Gayen, Jaur R; Trudeau, Vance; Corti, Angelo; Helle, Karen B

    2017-07-01

    The granin family comprises altogether 7 different proteins originating from the diffuse neuroendocrine system and elements of the central and peripheral nervous systems. The family is dominated by three uniquely acidic members, namely chromogranin A (CgA), chromogranin B (CgB) and secretogranin II (SgII). Since the late 1980s it has become evident that these proteins are proteolytically processed, intragranularly and/or extracellularly into a range of biologically active peptides; a number of them with regulatory properties of physiological and/or pathophysiological significance. The aim of this comprehensive overview is to provide an up-to-date insight into the distribution and properties of the well established granin-derived peptides and their putative roles in homeostatic regulations. Hence, focus is directed to peptides derived from the three main granins, e.g. to the chromogranin A derived vasostatins, betagranins, pancreastatin and catestatins, the chromogranin B-derived secretolytin and the secretogranin II-derived secretoneurin (SN). In addition, the distribution and properties of the chromogranin A-derived peptides prochromacin, chromofungin, WE14, parastatin, GE-25 and serpinins, the CgB-peptide PE-11 and the SgII-peptides EM66 and manserin will also be commented on. Finally, the opposing effects of the CgA-derived vasostatin-I and catestatin and the SgII-derived peptide SN on the integrity of the vasculature, myocardial contractility, angiogenesis in wound healing, inflammatory conditions and tumors will be discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Peptide Optical waveguides.

    Science.gov (United States)

    Handelman, Amir; Apter, Boris; Shostak, Tamar; Rosenman, Gil

    2017-02-01

    Small-scale optical devices, designed and fabricated onto one dielectric substrate, create integrated optical chip like their microelectronic analogues. These photonic circuits, based on diverse physical phenomena such as light-matter interaction, propagation of electromagnetic waves in a thin dielectric material, nonlinear and electro-optical effects, allow transmission, distribution, modulation, and processing of optical signals in optical communication systems, chemical and biological sensors, and more. The key component of these optical circuits providing both optical processing and photonic interconnections is light waveguides. Optical confinement and transmitting of the optical waves inside the waveguide material are possible due to the higher refractive index of the waveguides in comparison with their surroundings. In this work, we propose a novel field of bionanophotonics based on a new concept of optical waveguiding in synthetic elongated peptide nanostructures composed of ordered peptide dipole biomolecules. New technology of controllable deposition of peptide optical waveguiding structures by nanofountain pen technique is developed. Experimental studies of refractive index, optical transparency, and linear and nonlinear waveguiding in out-of-plane and in-plane diphenylalanine peptide nanotubes have been conducted. Optical waveguiding phenomena in peptide structures are simulated by the finite difference time domain method. The advantages of this new class of bio-optical waveguides are high refractive index contrast, wide spectral range of optical transparency, large optical nonlinearity, and electro-optical effect, making them promising for new applications in integrated multifunctional photonic circuits. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  4. Blind sequential lineup administration reduces both false identifications and confidence in those false identifications.

    Science.gov (United States)

    Charman, Steve D; Quiroz, Vanessa

    2016-10-01

    One of the most recommended procedures proposed by eyewitness experts is the use of double-blind lineups, in which the administrator does not know the identity of the suspect in the lineup. But despite the near universality of this recommendation, there is surprisingly little empirical research to support the claim that nonblind administration inflates false identifications. What little research has been conducted has shown conflicting findings with regard to the conditions under which nonblind administration affects false identifications, as well as its effects on witness confidence. The current study attempts to elucidate this effect. Student-participants (n = 312) were randomly assigned to play the role of either a lineup administrator (who were either told the identity of the suspect in the lineup or not) or a mock crime witness. Following unbiased instructions, administrators presented either a target-present or target-absent sequential lineup to the witness while being surreptitiously videorecorded. Nonblind administration significantly inflated false, but not correct, identifications, and significantly inflated witness confidence in those false identifications. Video recordings indicated that nonblind administrators were significantly more likely than blind administrators to smile (a) while the witness was viewing a photograph of the suspect, and (b) after a suspect identification. Results provide stronger support for the use of blind lineup administration by broadening the conditions under which nonblind administration is shown to inflate false identifications. Possible reconciliations for conflicting findings in the literature are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  5. Geophysics Fatally Flawed by False Fundamental Philosophy

    Science.gov (United States)

    Myers, L. S.

    2004-05-01

    For two centuries scientists have failed to realize Laplace's nebular hypothesis \\(1796\\) of Earth's creation is false. As a consequence, geophysicists today are misinterpreting and miscalculating many fundamental aspects of the Earth and Solar System. Why scientists have deluded themselves for so long is a mystery. The greatest error is the assumption Earth was created 4.6 billion years ago as a molten protoplanet in its present size, shape and composition. This assumption ignores daily accretion of more than 200 tons/day of meteorites and dust, plus unknown volumes of solar insolation that created coal beds and other biomass that increased Earth's mass and diameter over time! Although the volume added daily is minuscule compared with Earth's total mass, logic and simple addition mandates an increase in mass, diameter and gravity. Increased diameter from accretion is proved by Grand Canyon stratigraphy that shows a one kilometer increase in depth and planetary radius at a rate exceeding three meters \\(10 ft\\) per Ma from start of the Cambrian \\(540 Ma\\) to end of the Permian \\(245 Ma\\)-each layer deposited onto Earth's surface. This is unequivocal evidence of passive external growth by accretion, part of a dual growth and expansion process called "Accreation" \\(creation by accretion\\). Dynamic internal core expansion, the second stage of Accreation, did not commence until the protoplanet reached spherical shape at 500-600 km diameter. At that point, gravity-powered compressive heating initiated core melting and internal expansion. Expansion quickly surpassed the external accretion growth rate and produced surface volcanoes to relieve explosive internal tectonic pressure and transfer excess mass (magma)to the surface. Then, 200-250 Ma, expansion triggered Pangaea's breakup, first sundering Asia and Australia to form the Pacific Ocean, followed by North and South America to form the Atlantic Ocean, by the mechanism of midocean ridges, linear underwater

  6. Developmental trends in different types of spontaneous false memories: implications for the legal field.

    Science.gov (United States)

    Otgaar, Henry; Howe, Mark L; Peters, Maarten; Sauerland, Melanie; Raymaekers, Linsey

    2013-01-01

    In an emerging area of memory research, it is becoming apparent that one particular type of false memory, called spontaneous false memory, follows a developmental trajectory that is the opposite of what is commonly assumed in false memory research - that is, spontaneous false memories are more likely to occur in adults than in children. The present study focused on developmental trends of different types of spontaneous false memories. Specifically, in the current study, 6-8 year-olds, 10-12 year-olds, and adults were presented with two methods to induce spontaneous false memories: (i) semantically related word lists that are commonly used to evoke spontaneous false memories [i.e, Deese-Roediger-McDermott (DRM) paradigm]; and (ii) a video in which related details were not shown but were presented during a recognition task. The results showed that children were more likely to form false memories than adults in the video false memory paradigm, whereas DRM false memories were more evident in adults than in children. Furthermore, we found that on a general level, DRM false memories were positively related to video spontaneous false memories. We explain that stimuli that contain obvious themes attenuate or even reverse developmental trends in spontaneous false memories. Copyright © 2013 John Wiley & Sons, Ltd.

  7. Antibody responses to borrelia IR(6) peptide variants and the C6 peptide in Swedish patients with erythema migrans.

    Science.gov (United States)

    Tjernberg, Ivar; Sillanpää, Heidi; Seppälä, Ilkka; Eliasson, Ingvar; Forsberg, Pia; Lahdenne, Pekka

    2009-08-01

    The aim of this study was to evaluate the antibody responses to different VlsE protein IR(6) peptide variants and the synthetic C6 peptide in acute and convalescent (2-3 and 6 months) serum samples from Swedish patients with clinical erythema migrans (EM). Serum samples were prospectively collected from 148 patients with EM and compared to serum samples obtained from 200 healthy blood donors. The IgG responses to 3 IR(6) peptide variants originating from Borrelia burgdorferi (B. burgdorferi) sensu stricto, B. garinii, and B. afzelii were measured by enzyme-linked immunosorbent assays (ELISAs) and compared to a commercial C6 peptide ELISA. Seropositivity rate in the IR(6) or C6 peptide ELISAs ranged from 32% to 58% at presentation, 30-52% after 2-3 months, and 20-36% after 6 months. At presentation, positive antibodies in any of the 4 ELISAs were found in 66%. In 7/52 (13%), C6-negative EM cases, serological reaction was found to the B. burgdorferi sensu stricto-derived IR(6) peptide. In patients reporting previous LB compared to those without previous LB, significantly higher seropositivity rates were noted for all IR(6) peptides, but not for the C6 peptide. In the serology of EM in Europe, C6 ELISA does not seem to cover all cases. An ELISA using a mixture of B. burgdorferi sensu stricto IR(6) peptide and the C6 peptide could be of value in the serodiagnosis of LB in Europe. Further studies on combinations of variant IR(6) peptides and the C6 peptide in other manifestations of LB are needed to address this issue.

  8. Multimodal Imaging of Integrin Receptor-Positive Tumors by Bioluminescence, Fluorescence, Gamma Scintigraphy, and Single-Photon Emission Computed Tomography Using a Cyclic RGD Peptide Labeled with a Near-Infrared Fluorescent Dye and a Radionuclide

    Directory of Open Access Journals (Sweden)

    W. Barry Edwards

    2009-03-01

    Full Text Available Integrins, particularly the αvβ3 heterodimers, play important roles in tumor-induced angiogenesis and invasiveness. To image the expression pattern of the αvβ3 integrin in tumors through a multimodality imaging paradigm, we prepared a cyclic RGDyK peptide analogue (LS308 bearing a tetraazamacrocycle 1,4,7,10-tetraazacyclododecane-N, N′, N″, N‴-tetraacetic acid (DOTA and a lipophilic near-infrared (NIR fluorescent dye cypate. The αvβ3 integrin binding affinity and the internalization properties of LS308 mediated by the αvβ3 integrin in 4t1luc cells were investigated by receptor binding assay and fluorescence microscopy, respectively. The in vivo distribution of 111In-labeled LS308 in a 4t1luc tumor-bearing mouse model was studied by fluorescence, bioluminescence, planar gamma, and single-photon emission computed tomography (SPECT. The results show that LS308 has high affinity for αvβ3 integrin and internalized preferentially via the αvβ3 integrin-mediated endocytosis in 4t1luc cells. We also found that LS308 selectively accumulated in αvβ3-positve tumors in a receptor-specific manner and was visualized by the four imaging methods. Whereas the endogenous bioluminescence imaging identified the ensemble of the tumor tissue, the fluorescence and SPECT methods with the exogenous contrast agent LS308 reported the local expression of αvβ3 integrin. Thus, the multimodal imaging approach could provide important complementary diagnostic information for monitoring the efficacy of new antiangiogenic drugs.

  9. The prediction of organelle-targeting peptides in eukaryotic proteins with Grammatical-Restrained Hidden Conditional Random Fields.

    Science.gov (United States)

    Indio, Valentina; Martelli, Pier Luigi; Savojardo, Castrense; Fariselli, Piero; Casadio, Rita

    2013-04-15

    Targeting peptides are the most important signal controlling the import of nuclear encoded proteins into mitochondria and plastids. In the lack of experimental information, their prediction is an essential step when proteomes are annotated for inferring both the localization and the sequence of mature proteins. We developed TPpred a new predictor of organelle-targeting peptides based on Grammatical-Restrained Hidden Conditional Random Fields. TPpred is trained on a non-redundant dataset of proteins where the presence of a target peptide was experimentally validated, comprising 297 sequences. When tested on the 297 positive and some other 8010 negative examples, TPpred outperformed available methods in both accuracy and Matthews correlation index (96% and 0.58, respectively). Given its very low-false-positive rate (3.0%), TPpred is, therefore, well suited for large-scale analyses at the proteome level. We predicted that from ∼4 to 9% of the sequences of human, Arabidopsis thaliana and yeast proteomes contain targeting peptides and are, therefore, likely to be localized in mitochondria and plastids. TPpred predictions correlate to a good extent with the experimental annotation of the subcellular localization, when available. TPpred was also trained and tested to predict the cleavage site of the organelle-targeting peptide: on this task, the average error of TPpred on mitochondrial and plastidic proteins is 7 and 15 residues, respectively. This value is lower than the error reported by other methods currently available. The TPpred datasets are available at http://biocomp.unibo.it/valentina/TPpred/. TPpred is available on request from the authors. Supplementary data are available at Bioinformatics online.

  10. Peptide Integrated Optics.

    Science.gov (United States)

    Handelman, Amir; Lapshina, Nadezda; Apter, Boris; Rosenman, Gil

    2018-02-01

    Bio-nanophotonics is a wide field in which advanced optical materials, biomedicine, fundamental optics, and nanotechnology are combined and result in the development of biomedical optical chips. Silk fibers or synthetic bioabsorbable polymers are the main light-guiding components. In this work, an advanced concept of integrated bio-optics is proposed, which is based on bioinspired peptide optical materials exhibiting wide optical transparency, nonlinear and electrooptical properties, and effective passive and active waveguiding. Developed new technology combining bottom-up controlled deposition of peptide planar wafers of a large area and top-down focus ion beam lithography provides direct fabrication of peptide optical integrated circuits. Finding a deep modification of peptide optical properties by reconformation of biological secondary structure from native phase to β-sheet architecture is followed by the appearance of visible fluorescence and unexpected transition from a native passive optical waveguiding to an active one. Original biocompatibility, switchable regimes of waveguiding, and multifunctional nonlinear optical properties make these new peptide planar optical materials attractive for application in emerging technology of lab-on-biochips, combining biomedical photonic and electronic circuits toward medical diagnosis, light-activated therapy, and health monitoring. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Neural Global Pattern Similarity Underlies True and False Memories.

    Science.gov (United States)

    Ye, Zhifang; Zhu, Bi; Zhuang, Liping; Lu, Zhonglin; Chen, Chuansheng; Xue, Gui

    2016-06-22

    The neural processes giving rise to human memory strength signals remain poorly understood. Inspired by formal computational models that posit a central role of global matching in memory strength, we tested a novel hypothesis that the strengths of both true and false memories arise from the global similarity of an item's neural activation pattern during retrieval to that of all the studied items during encoding (i.e., the encoding-retrieval neural global pattern similarity [ER-nGPS]). We revealed multiple ER-nGPS signals that carried distinct information and contributed differentially to true and false memories: Whereas the ER-nGPS in the parietal regions reflected semantic similarity and was scaled with the recognition strengths of both true and false memories, ER-nGPS in the visual cortex contributed solely to true memory. Moreover, ER-nGPS differences between the parietal and visual cortices were correlated with frontal monitoring processes. By combining computational and neuroimaging approaches, our results advance a mechanistic understanding of memory strength in recognition. What neural processes give rise to memory strength signals, and lead to our conscious feelings of familiarity? Using fMRI, we found that the memory strength of a given item depends not only on how it was encoded during learning, but also on the similarity of its neural representation with other studied items. The global neural matching signal, mainly in the parietal lobule, could account for the memory strengths of both studied and unstudied items. Interestingly, a different global matching signal, originated from the visual cortex, could distinguish true from false memories. The findings reveal multiple neural mechanisms underlying the memory strengths of events registered in the brain. Copyright © 2016 the authors 0270-6474/16/366792-11$15.00/0.

  12. 'Lyell' Panorama inside Victoria Crater (False Color)

    Science.gov (United States)

    2008-01-01

    Photojournal note: This very large image (487.9 MB TIFF and 17.71 MB JPEG) may be too large for some web browsers to handle. Users may right-click on the TIFF or JPEG link in the legend above to download the file to their desktop. The image can then be viewed in an image manipulation application such as Adobe Photoshop. During four months prior to the fourth anniversary of its landing on Mars, NASA's Mars Exploration Rover Opportunity examined rocks inside an alcove called 'Duck Bay' in the western portion of Victoria Crater. The main body of the crater appears in the upper right of this stereo panorama, with the far side of the crater lying about 800 meters (half a mile) away. Bracketing that part of the view are two promontories on the crater's rim at either side of Duck Bay. They are 'Cape Verde,' about 6 meters (20 feet) tall, on the left, and 'Cabo Frio,' about 15 meters (50 feet) tall, on the right. The rest of the image, other than sky and portions of the rover, is ground within Duck Bay. Opportunity's targets of study during the last quarter of 2007 were rock layers within a band exposed around the interior of the crater, about 6 meters (20 feet) from the rim. Bright rocks within the band are visible in the foreground of the panorama. The rover science team assigned informal names to three subdivisions of the band: 'Steno,' 'Smith,' and 'Lyell.' This view combines many images taken by Opportunity's panoramic camera (Pancam) from the 1,332nd through 1,379th Martian days, or sols, of the mission (Oct. 23 to Dec. 11, 2007). Images taken through Pancam filters centered on wavelengths of 753 nanometers, 535 nanometers and 432 nanometers were mixed to produce this view, which is presented in a false-color stretch to bring out subtle color differences in the scene. Some visible patterns in dark and light tones are the result of combining frames that were affected by dust on the front sapphire window of the rover's camera. Opportunity landed on Jan. 25, 2004

  13. Effects of five-membered ring amino acid incorporation into peptides for coiled coil formation.

    Science.gov (United States)

    Oba, Makoto; Ito, Chika; Tanaka, Masakazu

    2018-03-01

    A five-membered ring amino acid (Ac 5 c), the peptides of which exhibit a preference for helical secondary structures, was introduced into peptides for the purpose of designing coiled coil peptides with high binding affinities. We prepared five types of peptides containing Ac 5 c with different numbers or at different positions. The incorporation of Ac 5 c into peptides enhanced their α-helicities; however, in contrast to our expectations, it did not result in stable coiled coil formation. The structures of side chains in hydrophobic amino acids, not α-helicities appeared to be important for stable hydrophobic interactions between peptides. Although we were unable to develop coiled coil peptides with high binding affinities, the present results will be useful for designing novel coiled coil peptides. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Synthetic antibiofilm peptides.

    Science.gov (United States)

    de la Fuente-Núñez, César; Cardoso, Marlon Henrique; de Souza Cândido, Elizabete; Franco, Octavio Luiz; Hancock, Robert E W

    2016-05-01

    Bacteria predominantly exist as multicellular aggregates known as biofilms that are associated with at least two thirds of all infections and exhibit increased adaptive resistance to conventional antibiotic therapies. Therefore, biofilms are major contributors to the global health problem of antibiotic resistance, and novel approaches to counter them are urgently needed. Small molecules of the innate immune system called host defense peptides (HDPs) have emerged as promising templates for the design of potent, broad-spectrum antibiofilm agents. Here, we review recent developments in the new field of synthetic antibiofilm peptides, including mechanistic insights, synergistic interactions with available antibiotics, and their potential as novel antimicrobials against persistent infections caused by biofilms. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Enhancing the Statistical Filtering Scheme to Detect False Negative Attacks in Sensor Networks

    Directory of Open Access Journals (Sweden)

    Muhammad Akram

    2017-06-01

    Full Text Available In this paper, we present a technique that detects both false positive and false negative attacks in statistical filtering-based wireless sensor networks. In statistical filtering scheme, legitimate reports are repeatedly verified en route before they reach the base station, which causes heavy energy consumption. While the original statistical filtering scheme detects only false reports, our proposed method promises to detect both attacks.

  16. Evolving the use of peptides as biomaterials components

    Science.gov (United States)

    Collier, Joel H.; Segura, Tatiana

    2012-01-01

    This manuscript is part of a debate on the statement that “the use of short synthetic adhesion peptides, like RGD, is the best approach in the design of biomaterials that guide cell behavior for regenerative medicine and tissue engineering”. We take the position that although there are some acknowledged disadvantages of using short peptide ligands within biomaterials, it is not necessary to discard the notion of using peptides within biomaterials entirely, but rather to reinvent and evolve their use. Peptides possess advantageous chemical definition, access to non-native chemistries, amenability to de novo design, and applicability within parallel approaches. Biomaterials development programs that require such aspects may benefit from a peptide-based strategy. PMID:21515167

  17. Gusev Rocks Solidified from Lava (False Color)

    Science.gov (United States)

    2006-01-01

    features investigated by Spirit during the Chinese New Year celebration period. In ancient Chinese myth, FuYi was the first great emperor and lived in the east. He explained the theory of 'Yin' and 'Yang' to his people, invented the net to catch fish, was the first to use fire to cook food, and invented a musical instrument known as the 'Se' to accompany his peoples' songs and dances. Other rocks and features are being informally named for Chinese gods, warriors, inventors, and scientists, as well as rivers, lakes, and mountains. Spirit took this image on the rover's Martian day, or sol, 731 (Jan. 23, 2006). This is a false-color composite combining images taken with the Pancam's 750-nanometer, 530-nanometer and 430-nanometer filters.

  18. Therapeutic HIV Peptide Vaccine

    DEFF Research Database (Denmark)

    Fomsgaard, Anders

    2015-01-01

    Therapeutic vaccines aim to control chronic HIV infection and eliminate the need for lifelong antiretroviral therapy (ART). Therapeutic HIV vaccine is being pursued as part of a functional cure for HIV/AIDS. We have outlined a basic protocol for inducing new T cell immunity during chronic HIV-1...... infection directed to subdominant conserved HIV-1 epitopes restricted to frequent HLA supertypes. The rationale for selecting HIV peptides and adjuvants are provided. Peptide subunit vaccines are regarded as safe due to the simplicity, quality, purity, and low toxicity. The caveat is reduced immunogenicity...

  19. Peptide Vaccine Against Paracoccidioidomycosis.

    Science.gov (United States)

    Taborda, Carlos P; Travassos, Luiz R

    2017-01-01

    The chapter reviews methods utilized for the isolation and characterization of a promising immunogen candidate, aiming at a human vaccine against paracoccidioidomycosis. Peptide P10 carries a T-CD4+ epitope and was identified as an internal sequence of the major diagnostic antigen known as gp43 glycoprotein. It successfully treated massive intratracheal infections by virulent Paracoccidioides brasiliensis in combination with chemotherapy.An introduction about the systemic mycosis was found essential to understand the various options that were considered to design prophylactic and therapeutic vaccine protocols using peptide P10.

  20. Sequencing Lys-N Proteolytic Peptides by ESI and MALDI Tandem Mass Spectrometry

    Science.gov (United States)

    Dupré, Mathieu; Cantel, Sonia; Verdié, Pascal; Martinez, Jean; Enjalbal, Christine

    2011-02-01

    In this study, we explored the MS/MS behavior of various synthetic peptides that possess a lysine residue at the N-terminal position. These peptides were designed to mimic peptides produced upon proteolysis by the Lys-N enzyme, a metalloendopeptidase issued from a Japanese fungus Grifola frondosa that was recently investigated in proteomic studies as an alternative to trypsin digestion, as a specific cleavage at the amide X-Lys chain is obtained that provides N-terminal lysine peptide fragments. In contrast to tryptic peptides exhibiting a lysine or arginine residue solely at the C-terminal position, and are thus devoid of such basic amino acids within the sequence, these Lys-N proteolytic peptides can contain the highly basic arginine residue anywhere within the peptide chain. The fragmentation patterns of such sequences with the ESI-QqTOF and MALDI-TOF/TOF mass spectrometers commonly used in proteomic bottom-up experiments were investigated.

  1. BIOACTIVE PEPTIDES OF THE COW MILK WHEY PROTEINS (Bos taurus

    Directory of Open Access Journals (Sweden)

    A. V. Iukalo

    2013-10-01

    Full Text Available Data on the biological functions of milk whey proteins, which are implemented at the level of their proteolytic degradation products — bioactive peptides have been reviewed. The main functions of these proteins is to provide the amino acid nutrition of mammals in the early stages of development, as well as the transport of fatty acids, retinol, involved in the synthesis of lactose, ions of calcium and iron, immune protection, antimicrobial action, etc. However, in recent years, it has been found that milk proteins like casein are precursors of biologically active peptides. Аngiotensin — converting enzyme, opioid peptides which are opiate receptor agonists, anti–microbial peptides, peptides with immunomodulatory and hypocholesterolemic action, and peptides affecting motility have been found among the products of proteolytic degradation of ?-lactoglobulin, ?-laktoalbumin, lactoferrin and milk whey albumin. Also data on the possible participation of peptides from milk whey proteins in the implementation of the biological functions of both the assimilation of calcium, antioxidant effect, the regulation of appetite, anticarcinogenic are provided. The authors assume that the phenomenon of bioactive peptides formation could be considered as an additional function of natural food proteins, which gives advantages to the mammals and has a positive effect on their development in the postnatal period. Ways of bioactive peptides formation, their resistance to action of proteolytic enzymes, the ability to cross into the bloodstream and have biological effects have been also discussed. Up to date, only a few products with bioactive peptides from milk whey proteins are obtained. Further studies of their structure, mechanism of action, ways of formation and methods of isolation are required for their wider use. Formation of functional products based on bioactive peptides from milk whey proteins will allow efficient use of milk whey, which is often a

  2. Implementing shared governance: a false start.

    Science.gov (United States)

    Hibberd, J M; Storoz, C E; Andrews, H A

    1992-03-01

    A case study of the implementation of shared governance in a large teaching hospital in Western Canada has been presented. The project was placed in jeopardy due to two major contingencies: turnover in the chief nursing executive position, and a sudden reduction in the operating budget of the nursing division necessitating significant layoffs. Other factors that threatened the survival of shared governance included lack of systematic, long-range planning; the number and diversity of major changes introduced concurrently in the nursing division; and insufficient support systems to sustain organizational change. In particular, some senior and first-line managers could not adapt to or accept the radical philosophical change and so they were unable to empower their staff and to provide the necessary reinforcement needed to ensure the success of shared governance. This combination of these factors contributed to the loss of momentum in the implementation of shared governance. Lowered morale in the wake of layoffs, together with union grievances, and lack of clarity of the role to be played by union representatives in shared governance produced conflict and confrontation within the nursing division and between union and management. Despite the difficulties encountered, there remains optimism and commitment to the challenge of making shared governance succeed. As this article goes to press, remarkable strides have been made in addressing the described issues. A task force composed primarily of staff nurses has developed a "customized" model of governance that meets the needs of the hospital and deals with the identified flaws of the first implementation attempt. The organization is optimistic that by taking time to develop a solid foundation for the proposed change and tending carefully to the details of decision-making processes, an effective structure to support the professional role of the nursing staff will be a reality.

  3. False memory ≠ false memory: DRM errors are unrelated to the misinformation effect.

    Directory of Open Access Journals (Sweden)

    James Ost

    Full Text Available The DRM method has proved to be a popular and powerful, if controversial, way to study 'false memories'. One reason for the controversy is that the extent to which the DRM effect generalises to other kinds of memory error has been neither satisfactorily established nor subject to much empirical attention. In the present paper we contribute data to this ongoing debate. One hundred and twenty participants took part in a standard misinformation effect experiment, in which they watched some CCTV footage, were exposed to misleading post-event information about events depicted in the footage, and then completed free recall and recognition tests. Participants also completed a DRM test as an ostensibly unrelated filler task. Despite obtaining robust misinformation and DRM effects, there were no correlations between a broad range of misinformation and DRM effect measures (mean r  = -.01. This was not due to reliability issues with our measures or a lack of power. Thus DRM 'false memories' and misinformation effect 'false memories' do not appear to be equivalent.

  4. False memory ≠ false memory: DRM errors are unrelated to the misinformation effect.

    Science.gov (United States)

    Ost, James; Blank, Hartmut; Davies, Joanna; Jones, Georgina; Lambert, Katie; Salmon, Kelly

    2013-01-01

    The DRM method has proved to be a popular and powerful, if controversial, way to study 'false memories'. One reason for the controversy is that the extent to which the DRM effect generalises to other kinds of memory error has been neither satisfactorily established nor subject to much empirical attention. In the present paper we contribute data to this ongoing debate. One hundred and twenty participants took part in a standard misinformation effect experiment, in which they watched some CCTV footage, were exposed to misleading post-event information about events depicted in the footage, and then completed free recall and recognition tests. Participants also completed a DRM test as an ostensibly unrelated filler task. Despite obtaining robust misinformation and DRM effects, there were no correlations between a broad range of misinformation and DRM effect measures (mean r  = -.01). This was not due to reliability issues with our measures or a lack of power. Thus DRM 'false memories' and misinformation effect 'false memories' do not appear to be equivalent.

  5. High Specific Selectivity and Membrane-Active Mechanism of Synthetic Cationic Hybrid Antimicrobial Peptides Based on the Peptide FV7.

    Science.gov (United States)

    Tan, Tingting; Wu, Di; Li, Weizhong; Zheng, Xin; Li, Weifen; Shan, Anshan

    2017-02-06

    Hybrid peptides integrating different functional domains of peptides have many advantages, such as remarkable antimicrobial activity, lower hemolysis and ideal cell selectivity, compared with natural antimicrobial peptides. FV7 (FRIRVRV-NH₂), a consensus amphiphilic sequence was identified as being analogous to host defense peptides. In this study, we designed a series of hybrid peptides FV7-LL-37 (17-29) (FV-LL), FV7-magainin 2 (9-21) (FV-MA) and FV7-cecropin A (1-8) (FV-CE) by combining the FV7 sequence with the small functional sequences LL-37 (17-29) (LL), magainin 2 (9-21) (MA) and cecropin A (1-8) (CE) which all come from well-described natural peptides. The results demonstrated that the synthetic hybrid peptides, in particular FV-LL, had potent antibacterial activities over a wide range of Gram-negative and Gram-positive bacteria with lower hemolytic activity than other peptides. Furthermore, fluorescent spectroscopy indicated that the hybrid peptide FV-LL exhibited marked membrane destruction by inducing outer and inner bacterial membrane permeabilization, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that FV-LL damaged membrane integrity by disrupting the bacterial membrane. Inhibiting biofilm formation assays also showed that FV-LL had similar anti-biofilm activity compared with the functional peptide sequence FV7. Synthetic cationic hybrid peptides based on FV7 could provide new models for combining different functional domains and demonstrate effective avenues to screen for novel antimicrobial agents.

  6. NCAM Mimetic Peptides: An Update

    DEFF Research Database (Denmark)

    Berezin, Vladimir; Bock, Elisabeth

    2008-01-01

    of combinatorial peptide libraries. The C3 and NBP10 peptides target the first Ig module whereas the ENFIN2 and ENFIN11 peptides target fibronectin type III (FN3) modules of NCAM. A number of NCAM mimetics can induce neurite outgrowth and exhibit neuroprotective and synaptic plasticity modulating properties...

  7. Design of pH-sensitive peptides from natural antimicrobial peptides for enhancing polyethylenimine-mediated gene transfection.

    Science.gov (United States)

    Zhang, Shi-Kun; Song, Jin-Wen; Li, Su-Bo; Gao, Hong-Wei; Chang, Hong-Yu; Jia, Li-Li; Gong, Feng; Tan, Ying-Xia; Ji, Shou-Ping

    2017-05-01

    Poor endosomal release is a major barrier of polyplex-mediated gene transfection. Antimicrobial peptides (AMPs) are commonly used to improve polyethylenimine (PEI)-mediated gene transfection by increasing endosomal release. In the present study, we designed novel pH-sensitive peptides that highly enhance transfection efficiency compared to their parent peptides. Two analogues of melittin (Mel) and RV-23 (RV) were synthesized by replacing the positively-charged residues in their sequences with glutamic acid residues. The pH-sensitive lysis ability of the peptides, the effect of the peptides on physicochemical characteristics, the intracellular trafficking, the transfection efficiency, and the cytotoxicity of the polyplexes were determined. The acidic peptides showed pH-sensitive lytic activity. The hemolytic activity of acidic peptides at pH 5.0 was higher than that at pH 7.4. The incorporation of acidic peptides did not affect the DNA binding ability of PEI but affected the physicochemical characteristics of the PEI/DNA polyplexes, which may be beneficial for endosomal release and gene transfection. The incorporation of acidic peptides into PEI/DNA polyplexes enhanced the PEI-mediated transfection efficiency corresponding to up to 42-fold higher luciferase activity compared to that of PEI alone. The results of the present study indicate that replacement of positively-charged residues with glutamic acid residues in the AMP sequence yields pH-sensitive peptides, which enhance the transfection efficiency of PEI/DNA polyplexes in various cell lines. Copyright © 2017 John Wiley & Sons, Ltd.

  8. brain natriuretic peptide

    African Journals Online (AJOL)

    Background: Recently brain natriuretic peptide (BNP) level has been introduced as a screening test for congestive heart failure (CHF) in children. The current CHF assessment scores are not satisfactory as they use a large number of variables. Objective: To evaluate two CHF scores: a modified clinical score and an echo-.

  9. Brain Peptides and Psychopharmacology

    Science.gov (United States)

    Arehart-Treichel, Joan

    1976-01-01

    Proteins isolated from the brain and used as drugs can improve and apparently even transfer mental states and behavior. Much of the pioneering work and recent research with humans and animals is reviewed and crucial questions that are being posed about the psychologically active peptides are related. (BT)

  10. Selective Acylation Enhances Membrane Charge Sensitivity of the Antimicrobial Peptide Mastoparan-X

    DEFF Research Database (Denmark)

    Etzerodt, Thomas Povl; Henriksen, Jonas Rosager; Rasmussen, Palle

    2011-01-01

    and positioning of the peptide in the membrane caused by either PA or OA acylation play a critical role in the fine-tuning of the effective charge of the peptide and thereby the fine-tuning of the peptide's selectivity between neutral and negatively charged lipid membranes. This finding is unique compared...... to previous reports where peptide acylation enhanced membrane affinity but also resulted in impaired selectivity. Our result may provide a method of enhancing selectivity of antimicrobial peptides toward bacterial membranes due to their high negative charge—a finding that should be investigated for other...

  11. NGR-peptide-drug conjugates with dual targeting properties.

    Directory of Open Access Journals (Sweden)

    Kata Nóra Enyedi

    Full Text Available Peptides containing the asparagine-glycine-arginine (NGR motif are recognized by CD13/aminopeptidase N (APN receptor isoforms that are selectively overexpressed in tumor neovasculature. Spontaneous decomposition of NGR peptides can result in isoAsp derivatives, which are recognized by RGD-binding integrins that are essential for tumor metastasis. Peptides binding to CD13 and RGD-binding integrins provide tumor-homing, which can be exploited for dual targeted delivery of anticancer drugs. We synthesized small cyclic NGR peptide-daunomycin conjugates using NGR peptides of varying stability (c[KNGRE]-NH2, Ac-c[CNGRC]-NH2 and the thioether bond containing c[CH2-CO-NGRC]-NH2, c[CH2-CO-KNGRC]-NH2. The cytotoxic effect of the novel cyclic NGR peptide-Dau conjugates were examined in vitro on CD13 positive HT-1080 (human fibrosarcoma and CD13 negative HT-29 (human colon adenocarcinoma cell lines. Our results confirm the influence of structure on the antitumor activity and dual acting properties of the conjugates. Attachment of the drug through an enzyme-labile spacer to the C-terminus of cyclic NGR peptide resulted in higher antitumor activity on both CD13 positive and negative cells as compared to the branching versions.

  12. Antimicrobial peptides interact with peptidoglycan

    Science.gov (United States)

    Neelay, Om P.; Peterson, Christian A.; Snavely, Mary E.; Brown, Taylor C.; TecleMariam, Ariam F.; Campbell, Jennifer A.; Blake, Allison M.; Schneider, Sydney C.; Cremeens, Matthew E.

    2017-10-01

    Traditional therapeutics are losing effectiveness as bacterial resistance increases, and antimicrobial peptides (AMPs) can serve as an alternative source for antimicrobial agents. Their mode of action is commonly hypothesized to involve pore formation in the lipid membrane, thereby leading to cell death. However, bacterial cell walls are much more complex than just the lipid membrane. A large portion of the wall is comprised of peptidoglycan, yet we did not find any report of AMP-peptidoglycan interactions. Consequently, this work evaluated AMP-peptidoglycan and AMP-phospholipid (multilamellar vesicles) interactions through tryptophan fluorescence. Given that peptidoglycan is insoluble and vesicles are large particles, we took advantage of the unique properties of Trp-fluorescence to use one technique for two very different systems. Interestingly, melittin and cecropin A interacted with peptidoglycan to a degree similar to vancomycin, a positive control. Whether these AMP-peptidoglycan interactions relate to a killing mode of action requires further study.

  13. [Biosynthesis of opioid peptides].

    Science.gov (United States)

    Rossier, J

    1988-01-01

    The endogenous opioid peptides all contain the enkephalin sequence Tyr-Gly-Gly-Phe-Met and Tyr-Gly-Gly-Phe-Leu at their aminoterminus. Three distinct families of these peptides (endorphins, enkephalins and dynorphins) are present in different neuronal pathways within the central nervous system. Molecular genetics have shown that these three families of opioid peptides are derived from three distinct precursors. Pro-opiomelanocortin gives rise to the endorphins, as well as adrenocorticotropic hormone (ACTH) and the melanotropic hormones (MSH's). [Met] enkephalin, [Leu] enkephalin and the related heptapeptide [Met] enkephalin-Arg6-Phe7 and octapeptide [Met] enkephalin-Arg6-Gly7-Leu8 are derived from proenkephalin. The third family is derived from prodynorphin and includes dynorphin A, dynorphin B (also known as rimorphin) and alpha- and beta-neo-endorphin. The structure of the genes coding for these precursors are similar, suggesting the possibility of one common ancestral gene. The most common scheme for enzymatic maturation of precursors proposes the action of a trypsin-like endopeptidase followed by a carboxypeptidase B-like exopeptidase. However, we have provided evidence that this combination of trypsin-like and carboxypeptidase B-like enzymes may not be the only mechanism for liberating enkephalin from low molecular weight enkephalin-containing peptides. Indeed, endo-oligopeptidase A, an enzyme, known to hydrolyze the Phe5-Ser6 bond of bradykinin and the Arg8-Arg9 bond of neurotensin, has been shown to produce, by a single cleavage, [Leu] enkephalin or [Met] enkephalin from small enkephalin-containing peptides, (Camargo et al., 1987, J. Neurochem. 48, 1258-1263).(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Biochemical functionalization of peptide nanotubes with phage displayed peptides

    Science.gov (United States)

    Swaminathan, Swathi; Cui, Yue

    2016-09-01

    The development of a general approach for the biochemical functionalization of peptide nanotubes (PNTs) could open up existing opportunities in both fundamental studies as well as a variety of applications. PNTs are spontaneously assembled organic nanostructures made from peptides. Phage display has emerged as a powerful approach for identifying selective peptide binding motifs. Here, we demonstrate for the first time the biochemical functionalization of PNTs via peptides identified from a phage display peptide library. The phage-displayed peptides are shown to recognize PNTs. These advances further allow for the development of bifunctional peptides for the capture of bacteria and the self-assembly of silver particles onto PNTs. We anticipate that these results could provide significant opportunities for using PNTs in both fundamental studies and practical applications, including sensors and biosensors nanoelectronics, energy storage devices, drug delivery, and tissue engineering.

  15. Controlling the local false discovery rate in the adaptive Lasso

    KAUST Repository

    Sampson, J. N.

    2013-04-09

    The Lasso shrinkage procedure achieved its popularity, in part, by its tendency to shrink estimated coefficients to zero, and its ability to serve as a variable selection procedure. Using data-adaptive weights, the adaptive Lasso modified the original procedure to increase the penalty terms for those variables estimated to be less important by ordinary least squares. Although this modified procedure attained the oracle properties, the resulting models tend to include a large number of "false positives" in practice. Here, we adapt the concept of local false discovery rates (lFDRs) so that it applies to the sequence, λn, of smoothing parameters for the adaptive Lasso. We define the lFDR for a given λn to be the probability that the variable added to the model by decreasing λn to λn-δ is not associated with the outcome, where δ is a small value. We derive the relationship between the lFDR and λn, show lFDR =1 for traditional smoothing parameters, and show how to select λn so as to achieve a desired lFDR. We compare the smoothing parameters chosen to achieve a specified lFDR and those chosen to achieve the oracle properties, as well as their resulting estimates for model coefficients, with both simulation and an example from a genetic study of prostate specific antigen.

  16. Adults' Memories of Childhood: True and False Reports

    Science.gov (United States)

    Qin, Jianjian; Ogle, Christin M.; Goodman, Gail S.

    2008-01-01

    In 3 experiments, the authors examined factors that, according to the source-monitoring framework, might influence false memory formation and true/false memory discernment. In Experiment 1, combined effects of warning and visualization on false childhood memory formation were examined, as were individual differences in true and false childhood…

  17. 10 CFR 1008.14 - Requests under false pretenses.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Requests under false pretenses. 1008.14 Section 1008.14... for Access or Amendment § 1008.14 Requests under false pretenses. Subsection (i)(3) of the Act... individual from an agency under false pretenses shall be quilty of a misdeamenaor and fined not more than $5...

  18. 7 CFR 160.90 - False, misleading, or deceitful practices.

    Science.gov (United States)

    2010-01-01

    ... REGULATIONS AND STANDARDS FOR NAVAL STORES Labeling, Advertising and Packing § 160.90 False, misleading, or... 7 Agriculture 3 2010-01-01 2010-01-01 false False, misleading, or deceitful practices. 160.90... commerce or of anything offered as such shall be false, misleading, or deceitful in any manner. ...

  19. Intelligent portal monitor for fast suppression of false positives due to radiopharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, M.W.; Butterfield, K.B.

    1985-01-01

    Monitoring the movement of radioactive material through secure or sensitive areas may be complicated by the existence of unanticipated sources of radiation carried by individuals passing through the area. Typical of such sources are radiopharmaceuticals prescribed for a medical procedure. We report here on an apparatus designed to quickly discriminate between in-vivo radiopharmaceuticals and other nuclear materials, based on a pattern-recognition algorithm and a microcomputer. Principles of operation are discussed, and the data base for the pattern-recognition algorithm is displayed. Operating experience with the apparatus in a trial location is also discussed. Our apparatus correctly identifies in-vivo radiopharmaceuticals in over 80% of all trials; challenges with radioisotopes other than radiopharmaceuticals have led the apparatus, without exception, to reject the challenge isotope as incompatible with medical practice. The apparatus thus rapidly discriminates between individuals bearing radiopharmaceuticals and those bearing illicit sources, such as special nuclear materials. Examples of applications are presented. 7 refs., 4 figs., 1 tab.

  20. Ethnic hair care products may increase false positives in hair drug testing.

    Science.gov (United States)

    Kidwell, David A; Smith, Frederick P; Shepherd, Arica R

    2015-12-01

    The question of why different races appear more susceptible to hair contamination by external drugs remains controversial. This research studied susceptibility of head hair to external cocaine and methamphetamine when hair products have been applied. Three different chemical classes of ethnic hair products were applied to Caucasian, Asian, and African hair. Some products increased the methamphetamine and cocaine concentrations in all hair types. A unique finding of this research is that certain ethnic hair products can replace moisture as a diffusion medium, thereby increasing the susceptibility to contamination over 100-fold compared to petroleum-based products. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.