scholarly journals A relative quantitation method for measuring DNA methylation and hydroxymethylation using guanine as an internal standard

2021 ◽  
Author(s):  
Krisztina Németh ◽  
Katalin Mészáros ◽  
Borbála Szabó ◽  
Henriett Butz ◽  
Tamás Arányi ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Internal Standard ◽  
Relative Quantitation ◽  
Quantitation Method

A relative LC-MS/MS quantitation method for DNA methylation study, where in situ guanine was used as internal standard.

Isomer Specific Assay of Ester and Salt Formulations of 2,4-Dichlorophenoxyacetic Acid by High Pressure Liquid Chromatography: Collaborative Study

1978 ◽  
Vol 61 (5) ◽  
pp. 1163-1165 ◽  
Author(s):  
Timothy S Stevens ◽  
Norman E Skelly ◽  
Robert B Grorud
Keyword(s):  
High Pressure ◽  
Collaborative Study ◽  
Internal Standard ◽  
Dichlorophenoxyacetic Acid ◽  
High Pressure Liquid Chromatographic ◽  
Coefficients Of Variation ◽  
Standard Solution ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Liquid Chromatographic

Abstract A high pressure liquid chromatographic (HPLC) assay of ester and salt formulations of 2,4-D has been collaboratively studied. The method is specific for 2,4-D isomer and resolves all known impurities from 2,4-D and the internal standard p-bromophenol. In situ saponification, at room temperature, is performed by adding a combined saponification-internal standard solution to ester products. The same saponification- internal standard solution is added to amine salts and the analytical standard. The injected aqueous potassium salt solution of 2,4-D is then converted to the acid form by an acidic buffered mobile solvent of 20% acetonitrile in water. Optimum chromatography is attained by a mobile solvent pH of 2.95 in a reverse phase microparticulate column, by ion suppression. Each of the 9 collaborators received 3 different ester and 2 different amine formulations of 2,4-D. The coefficients of variation of 2,4-D acid equivalent ranged from 1.22 to 1.59%. The method has been adopted as official first action.

scholarly journals In situ electrochemical characterisation of graphene and various carbon-based electrode materials: an internal standard approach

RSC Advances ◽  
2015 ◽  
Vol 5 (47) ◽  
pp. 37281-37286 ◽  
Author(s):  
Dale A. C. Brownson ◽  
Peter J. Kelly ◽  
Craig E. Banks
Keyword(s):  
Electrode Materials ◽  
Internal Standard ◽  
Standard Approach ◽  
Standard Protocol ◽  
Electrochemical Characterisation ◽  
Carbon Based

An internal standard protocol is utilised to simultaneously characterise and utilise carbon-based electrode materials during their implementation.

scholarly journals Application of the MSAP Technique to Evaluate Epigenetic Changes in Plant Conservation

2020 ◽  
Vol 21 (20) ◽  
pp. 7459
Author(s):  
María Elena González-Benito ◽  
Miguel Ángel Ibáñez ◽  
Michela Pirredda ◽  
Sara Mira ◽  
Carmen Martín
Keyword(s):  
Dna Methylation ◽  
In Situ Conservation ◽  
Plant Conservation ◽  
Ex Situ ◽  
Conservation Strategies ◽  
Regenerated Plants ◽  
Before And After ◽  
Methylation Patterns

Epigenetic variation, and particularly DNA methylation, is involved in plasticity and responses to changes in the environment. Conservation biology studies have focused on the measurement of this variation to establish demographic parameters, diversity levels and population structure to design the appropriate conservation strategies. However, in ex situ conservation approaches, the main objective is to guarantee the characteristics of the conserved material (phenotype and epi-genetic). We review the use of the Methylation Sensitive Amplified Polymorphism (MSAP) technique to detect changes in the DNA methylation patterns of plant material conserved by the main ex situ plant conservation methods: seed banks, in vitro slow growth and cryopreservation. Comparison of DNA methylation patterns before and after conservation is a useful tool to check the fidelity of the regenerated plants, and, at the same time, may be related with other genetic variations that might appear during the conservation process (i.e., somaclonal variation). Analyses of MSAP profiles can be useful in the management of ex situ plant conservation but differs in the approach used in the in situ conservation. Likewise, an easy-to-use methodology is necessary for a rapid interpretation of data, in order to be readily implemented by conservation managers.

scholarly journals Triage of hrHPV-positive women: comparison of two commercial methylation-specific PCR assays

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Carolin Dippmann ◽  
Martina Schmitz ◽  
Kristina Wunsch ◽  
Stefanie Schütze ◽  
Katrin Beer ◽  
...  
Keyword(s):  
Dna Methylation ◽  
False Positive ◽  
Pap Smear ◽  
Intraepithelial Neoplasia ◽  
Molecular Diagnostic ◽  
Cervical Lesions ◽  
Detection Rates ◽  
Diagnostic Assays ◽  
Specific Pcr

Abstract Aim High-risk human papillomavirus (hrHPV)-based screening is becoming increasingly important, either by supplementing or replacing the traditional cytology-based cervical Pap smear. However, hrHPV screening lacks specificity, because it cannot differentiate between transient virus infection and clinically relevant hrHPV-induced disease. Therefore, reliable triage methods are needed for the identification of HPV-positive women with cervical intraepithelial neoplasia (CIN) in need of treatment. Promising tools discussed for the triage of these patients are molecular diagnostic tests based on epigenetic markers. Here, we compare the performance of two commercially available DNA methylation-based diagnostic assays—GynTect® and the QIAsure Methylation Test—in physician-taken cervical scrapes from 195 subjects. Findings Both GynTect® and the QIAsure Methylation Test detected all cervical carcinoma and carcinoma in situ (CIS). The differences observed in the detection rates between both assays for the different grades of cervical lesions (QIAsure Methylation Test: CIN1 26.7%, CIN2 27.8% and CIN3 74.3%; GynTect®: CIN1 13.3%, CIN2 33.3% and CIN3 60%) were not significant. Concerning the false-positive rates, significant differences were evident. For the healthy (NILM) hrHPV-positive group, the false-positive rates were 5.7% for GynTect® and 26.4% for QIAsure Methylation Test (p = 0.003) and for the NILM hrHPV-negative group 2.2% vs. 23.9% (p = 0.006), respectively. When considering hrHPV-positive samples only for comparison (n = 149), GynTect® delivered significantly higher specificity compared to the QIAsure Methylation Test for CIN2 + (87.6% vs. 67.4% (p < 0.001)) and CIN3 + (84.1% vs. 68.2% (p = 0.002)). Overall our findings suggest that DNA methylation-based tests are suitable for the triage of hrHPV-positive women. With the goal to provide a triage test that complements the limited specificity of HPV testing in HPV-based screening, GynTect® may be preferable, due to its higher specificity for CIN2+ or CIN3+ .

Abstract 412: DNA methylation in ductal carcinoma in situ and its relation with disease progression

2014 ◽  
Author(s):  
Kevin C. Johnson ◽  
Panpan Chen ◽  
Devin Koestler ◽  
Julia E. Weiss ◽  
Erik G. Jenson ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Disease Progression ◽  
Ductal Carcinoma In Situ ◽  
Carcinoma In Situ ◽  
Ductal Carcinoma

scholarly journals DNA Methylation Changes in Atypical Adenomatous Hyperplasia, Adenocarcinoma In Situ, and Lung Adenocarcinoma

PLoS ONE ◽  
2011 ◽  
Vol 6 (6) ◽  
pp. e21443 ◽  
Author(s):  
Suhaida A. Selamat ◽  
Janice S. Galler ◽  
Amit D. Joshi ◽  
M. Nicky Fyfe ◽  
Mihaela Campan ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Lung Adenocarcinoma ◽  
Adenocarcinoma In Situ ◽  
Atypical Adenomatous Hyperplasia ◽  
Adenomatous Hyperplasia

scholarly journals Hydration Study of Synthetic Yeelimite using LXRPD and SXRPD

2014 ◽  
Vol 70 (a1) ◽  
pp. C1096-C1096
Author(s):  
Ana Cuesta ◽  
Gema Alvarez Pinazo ◽  
Angeles De la Torre ◽  
Susana Sanfélix ◽  
Inmaculada Peral ◽  
...  
Keyword(s):  
Standard Method ◽  
Internal Standard ◽  
Free Water ◽  
Ex Situ ◽  
Quantitative Phase Analysis ◽  
Internal Standard Method ◽  
X Rays ◽  
X Ray ◽  
External Standard Method

XRPD is a powerful tool for material characterization in general, and for in-situ studies of chemical processes in particular. The use of an intense X-ray source, .i.e. synchrotron X-rays, coupled with fast X-ray detection permits time-resolved diffraction experiments allowing in-situ quantitative phase analysis during the early ages of cement hydration. Calcium sulfoaluminate, CSA, cements may have variable compositions, but all of them contain high amounts of ye'elimite, Ca4Al6O12SO4. Commercial CSA cements have special applications such as high strength developments at early-ages. Ye'elimite is very reactive and most of its hydration heat is released during the first eight hours of hydration . The aim of this work is to better understand the early age hydration of stoichiometric (orthorhombic) and doped (pseudo-cubic) ye'elimite samples. The parameters studied by SXRPD, LXRPD and calorimetry have been: polymorphism; water/ye'elimite ratio; and sulfate (gypsum and anhydrite) contents. This work has allowed establishing mechanisms and kinetics for hydration of ye'elimite samples by in-situ SXRPD with internal standard methodology. Moreover, pastes were also studied by ex-situ LXRPD with the external standard method, G-factor, at 2 and 7 days. Both strategies were able to quantify the amorphous contents, including free water. It is important to highlight that the results obtained at early ages, by the internal standard method, are in agreement with those obtained at later ages, G-method, showing the consistence and complementarity of both methodologies. The hydration of stoichiometric ye'elimite in the presence of gypsum is strongly hastened, when compared to the hydration process without gypsum. However, the presence of gypsum has a little effect in the hydration of doped ye'elimite. Moreover, anhydrite has also accelerated the hydration of stoichiometric ye'elimite, although its lower solubility has provoked the formation of an intermediate phase in the first hours.

scholarly journals Frequent aberrant DNA methylation of ABCB1, FOXC1, PPP2R2B and PTEN in ductal carcinoma in situ and early invasive breast cancer

2010 ◽  
Vol 12 (1) ◽  
Author(s):  
Aslaug Aa Muggerud ◽  
Jo Anders Rønneberg ◽  
Fredrik Wärnberg ◽  
Johan Botling ◽  
Florence Busato ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Methylation ◽  
Ductal Carcinoma In Situ ◽  
Invasive Breast Cancer ◽  
Carcinoma In Situ ◽  
Ductal Carcinoma ◽  
Aberrant Dna Methylation

Cytological and electrophoretic analysis of DNA methylation in the holocentric chromosomes of Megoura viciae (Homoptera, Aphididae)

Genome ◽  
1994 ◽  
Vol 37 (4) ◽  
pp. 625-630 ◽  
Author(s):  
G. C. Manicardi ◽  
D. Bizzaro ◽  
P. Azzoni ◽  
U. Bianchi
Keyword(s):  
Dna Methylation ◽  
Dna Extraction ◽  
Electrophoretic Analysis ◽  
Holocentric Chromosomes ◽  
Molecular Weights ◽  
Electrophoretic Patterns ◽  
Cytological Data ◽  
Megoura Viciae ◽  
Methylation Patterns

Chromosomal and purified DNA methylation patterns were determined in the holocentric chromosomes of Megoura viciae by treatment with MspI and HpaII. Both enzymes produced a clear C-like banding pattern but widely digested one telomere of the X chromosome, which appeared as heterochromatic after C-banding treatment and brightly fluorescent after chromomycin A3 staining. Quantitative microfluorometric evaluations of DNA extraction performed on cytological preparations showed that both isoschizomers resulted in the same DNA extraction (about 30%). Contrary to what was found by in situ endonuclease treatment, the electrophoretic patterns of purified and digested DNA showed that digestion with MspI was slightly more extensive than that with HpaII in a zone of fragments ranging from 23 to 9 kb. This result indicates that aphid chromatin is not wholly unmethylated. The discrepancy between electrophoretic and cytological data has been explained by taking into consideration that DNA fragments with high molecular weights could be cleaved in situ by the enzymes but not extracted from the chromatin.Key words: aphids, DNA methylation, holocentric chromosomes, heterochromatin, restriction enzyme bandings.

Sign in / Sign up

Export Citation Format

Share Document