ABSTRACT
Optimization and validation for simultaneous quantitation of four aflatoxins B1, B2, G1, and G2 in peanuts and raisins were performed on ultra-performance liquid chromatography in a combination of fluorescence detector, without derivatization. The advantages were short analysis time, simple sample handling, and reduced solvent consumption. Instrument detection limits of AFB1, AFB2, AFG1, and AFG2 were 0.07, 0.01, 0.1, and 0.008 µg/kg, respectively, lower than those obtained by LCMSMS and HPLC-FLD with derivatization. Two solvent mixtures were chosen for two different matrices whose matrix effect was not negligible (2.81%-8.04% for peanuts and 5.63%-11.43% for raisins). The linear ranges were from 0.2 to 20 µg/L for AFB1 and AFG1 and from 0.05 to 5 µg/L for AFB2 and AFG2. The limits of detection and quantification were 0.025-0.1 and 0.075-0.3 µg/kg for peanuts and raisins, respectively. Recoveries at three other concentrations from 0.75 to 125 µg/kg of total aflatoxins were obtained between 76.5% and 99.8% (with RSD < 6%) following the SANTE 11312/2021. Validation parameters complied with the requirements of ISO/IEC 17025:2017. The extracts and the sample could be stabilized at 4°C and 20°C for 24 h and at -20°C for up to 21 days, respectively. Thus, the study can be used as a standard method for the analysis of Aflatoxins (AFs) in peanut and raisin matrices. Investigation of 350 peanut samples collected at Markets in the central districts of HCM city showed that 28.6% were contaminated with AFB1 from 0.31 up to 554 µg/kg; 13.4% contained AFB2, and 5.7% of AFG1 in the range of 0.4-53 µg/kg and 0.4-9.57 µg/kg, respectively; AFG2 (about 0.6%) was detected from 0.45 to 0.75 µg/kg. Meanwhile, 12.8% exceeded the total aflatoxins limit, and 13.4% exceeded the AFB1 limit. AFs were almost not found in the 350 raisin samples.
ABSTRACT
BACKGROUND: DNA methylation on cytosine in the CpG dinucleotides is one of the most common epigenetic perturbations taking place during cancer initiation, progression, occurrence and resistance therapy. DNA methylation seems to be sufficiently stable epigenetic modification to be utilized as a cancer biomarker in in vitro diagnostic (IVD) settings. Nowadays, the SHOX2 methylation (mSHOX2) is one of the most valuable DNA methylation biomarkers of lung cancer that is the leading cause of cancer death. It is being continuously validated across ethnicities, lifestyles and lifespan. This study focused on characteristics of mSHOX2 in Vietnamese patients with lung cancer since a lack of investigation and evidence of its utility in this country. METHODS: The probe and primer sets were designed according to the MethyLight method for quantitative assessment of the mSHOX2 in 214 formalin-fixed paraffin-embedded (FFPE) lung tissues and 57 plasma samples. RESULTS: mSHOX2 in FFPE tissues allowed discriminating benign and malignant lung diseases with 60% (95% CI 50.7-68.8%) sensitivity and 90.4% (95% CI 82.6-95.5%) specificity. Importantly, based on mSHOX2 in plasma, lung cancer could be detected with 83.3% (95% CI 65.3-94.4%) sensitivity and 92.6% (95% CI 75.7-99.1%) specificity, respectively. There were insignificant associations between mSHOX2 with age, cancer stage, EGFR mutation and serum CEA, CYFRA21-1 concentrations except for that gender. CONCLUSION: Our study indicated that mSHOX2 was satisfactory for distinguishing malignant from benign lung tissue and noninvasively detecting lung cancer.
Subject(s)
DNA Methylation , Homeodomain Proteins , Lung Neoplasms , Antigens, Neoplasm , Asian People , Biomarkers, Tumor/genetics , Homeodomain Proteins/genetics , Humans , Keratin-19 , Lung Neoplasms/pathologyABSTRACT
Statistical methods for constructing confidence intervals for the probability content in a specified interval are proposed. Exact and approximate solutions based on the fiducial approach are described when the measurements on the variable of interest can be modelled by a location-scale (or log-location-scale) distribution. Methods are described for the normal, Weibull, two-parameter exponential and two-parameter Rayleigh distributions. For each case, the solutions are evaluated for their merits. Three examples, where it is desired to estimate the percentages of engineering products meet the specification limits, are provided to illustrate the methods.
ABSTRACT
The problems of interval estimating the parameters and the mean of a two-parameter Rayleigh distribution are considered. We propose pivotal-based methods for constructing confidence intervals for the mean, quantiles, survival probability and for constructing prediction intervals for the mean of a future sample. Pivotal quantities based on the maximum likelihood estimates (MLEs), moment estimates (MEs) and the L-moments estimates (L-MEs) are proposed. Interval estimates based on them are compared via Monte Carlo simulation. Comparison studies indicate that the results based on the MEs and the L-MEs are very similar. The results based on the MLEs are slightly better than those based on the MEs and the L-MEs for small to moderate sample sizes. The methods are illustrated using an example involving lifetime data.