scholarly journals MS/MS/MS Reveals False Positive Identification of Histone Serine Methylation

2010 ◽  
Vol 9 (1) ◽  
pp. 585-594 ◽  
Author(s):  
Junmei Zhang ◽  
Yue Chen ◽  
Zhihong Zhang ◽  
Gang Xing ◽  
Joanna Wysocka ◽  
...  
Keyword(s):  
False Positive ◽  
Positive Identification ◽  
False Positive Identification

scholarly journals Population Admixture May Appear to Mask, Change or Reverse Genetic Effects of Genes Underlying Complex Traits

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 1319-1323
Author(s):  
Hong-Wen Deng
Keyword(s):  
Population Genetics ◽  
False Positive ◽  
Complex Traits ◽  
Association Studies ◽  
Genetic Effects ◽  
Population Admixture ◽  
Reverse Genetic ◽  
Positive Identification ◽  
False Positive Identification

Abstract Association studies using random population samples are increasingly being applied in the identification and inference of genetic effects of genes underlying complex traits. It is well recognized that population admixture may yield false-positive identification of genetic effects for complex traits. However, it is less well appreciated that population admixture can appear to mask, change, or reverse true genetic effects for genes underlying complex traits. By employing a simple population genetics model, we explore the effects and the conditions of population admixture in masking, changing, or even reversing true genetic effects of genes underlying complex traits.

False-positive identification ofEscherichia coliin treated municipal wastewater and wastewater-irrigated soils

2011 ◽  
Vol 57 (10) ◽  
pp. 775-784 ◽  
Author(s):  
Jean E.T. McLain ◽  
Channah M. Rock ◽  
Kathleen Lohse ◽  
James Walworth
Keyword(s):  
Water Quality ◽  
False Positive ◽  
Municipal Wastewater ◽  
Inorganic Compounds ◽  
Treated Wastewater ◽  
Technical Literature ◽  
E Coli ◽  
Positive Identification ◽  
False Positive Identification ◽  
Irrigated Soils

The increasing use of treated wastewater for irrigation heightens the importance of accurate monitoring of water quality. Chromogenic media, because they are easy to use and provide rapid results, are often used for detection of Escherichia coli in environmental samples, but unique levels of organic and inorganic compounds alter the chemistry of treated wastewater, potentially hindering the accurate performance of chromogenic media. We used MI agar and molecular confirmatory methods to assess false-positive identification of E. coli in treated wastewater samples collected from municipal utilities, an irrigation holding pond, irrigated soils, and in samples collected from storm flows destined for groundwater recharge. False-positive rates in storm flows (4.0%) agreed closely with USEPA technical literature but were higher in samples from the pond, soils, and treatment facilities (33.3%, 38.0%, and 48.8%, respectively). Sequencing of false-positive isolates confirmed that most were, like E. coli, of the family Enterobacteriaceae, and many of the false-positive isolates were reported to produce the β-d-glucuronidase enzyme targeted by MI agar. False-positive identification rates were inversely related to air temperature, suggesting that seasonal variations in water quality influence E. coli identification. Knowledge of factors contributing to failure of chromogenic media will lead to manufacturer enhancements in media quality and performance and will ultimately increase the accuracy of future water quality monitoring programs.

False Positive Identification

1978 ◽  
Vol 18 (4) ◽  
pp. 255-262 ◽  
Author(s):  
E. Linden Hilgendorf ◽  
B. L. Irving
Keyword(s):  
False Positive ◽  
Waiting Room ◽  
Positive Identification ◽  
False Positive Identification ◽  
High Level

This paper reports the results of a simulation of an identification parade using recommended procedures. The parade was held three days after subjects had been incidental observers of a man in a waiting room. The Parade included ‘a suspect’ who was not the man Previously seen. Of the 68 subjects, 21 made a false Positive identification on the parade, including 6 who made an identification with a high level of certainty. All these 6 high certainty identifications were of ‘the suspect’. A group of subjects also saw a set of photographs prior to the parade. The findings suggest that, When the man previously seen was not included, subjects were more likely to make a false positive identification on photographs than on a parade. In addition, subjects who had seen the photographs Wade a significantly greater proportion of false positive identifications on the subsequent parade.

scholarly journals Managing Risks Associated with Establishing the Metabolome of Dietary Phytochemicals (P06-010-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Colin Kay ◽  
Jessica Everhart ◽  
Atul Rathore
Keyword(s):  
Gas Phase ◽  
False Positive ◽  
Method Development ◽  
Ion Trap ◽  
Reference Standards ◽  
Molecular Rearrangement ◽  
Positive Identification ◽  
Hydrogen Elimination ◽  
False Positive Identification ◽  
Dietary Phytochemicals

Abstract Objectives Establishing the metabolome of dietary phytochemicals is complicated by the influence of the microbiome. Due to large numbers of human, microbial and hybrid human-microbial metabolites, false-positive identification via mass spectrometry (MS) is probable. Users must be aware of the influence of matrix and instrumental background environment upon the mass spectrum, which produce spectral features arising from fragmentation, gas-phase artifacts, molecular rearrangement, quasi-molecular ion or radical formation. Hydroxylated cyclic and polycyclic structures such as polyphenols are prone to multiple gas-phase artifacts, including water elimination (loss −17), hydrogen elimination (−1), radical fragmentation (loss −15, −14), Retro-Diels-Alder reactions (C-ring electron rearrangement; + or −2), or combinations thereof. In-source fragmentation is often observed for phase II conjugates, such as sulfate, glucuronide and glycine. Finally, polyphenol metabolites such as valerolactones, benzoic, phenylpropanoic and phenylacetic acids, are also products of MS fragmentation. As there are few reference standards available for confirmation or optimization, false-positive identification is likely. The objective of the present study was to highlight limitations with MS to ensure researchers make appropriate assumptions from their spectral data. Methods A quantitative metabolomics database comprising optimized spectral signals for fragmentation profiling of over 400 poly/phenols and metabolites was established using a UHPLC-coupled electrospray triple quadrupole-linear ion trap mass spectrometer (SCIEX QTRAP 6500+). Methods were established and utilized to interrogate over 3000 biospecimens derived from studies feeding various polyphenol-rich diets. Results Scanning for numerous metabolites reported in the literature using single transition monitoring, in both neat and extracted human and animal tissue matrices consistently identify peaks which were either artifacts, isomers, fragments or background noise, as confirmed relative to authentic reference standards. Conclusions Without ample MS experience, method development, validation and data interrogation, falsely identified metabolites will continue to occur and undoubtedly hinder future discovery. Funding Sources NIFA-USDA Hatch 1011757.

Identification of Early Stuttering

1992 ◽  
Vol 1 (4) ◽  
pp. 21-27 ◽  
Author(s):  
Mark Onslow
Keyword(s):  
At Risk ◽  
False Positive ◽  
False Negative ◽  
Consensus Definition ◽  
Single Observation ◽  
Positive Identification ◽  
False Positive Identification ◽  
Definition Of

Strategies to identify early stuttering are discussed. These strategies involve two components, one for positive identification and one for negative identification. It is argued that false negative identification of early stuttering warrants more concern than false positive identification. Accordingly, identification strategies are suggested that are intended to eliminate false negative identification. The positive identification of early stuttering is based on Bloodstein’s (1987) consensus definition of the disorder, and on a single observation at one point in time. Negative identification is based on all available definitions and is not a consequence of a failure to make a positive identification. Provision is made for an "at-risk" register, as suggested by Adams (1977), where a child is observed regularly for a period of time before final identification, positive or negative, is made. The strategies are described in detail and some issues associated with them are discussed.

Sign in / Sign up

Export Citation Format

Share Document