Automated In-Injector Derivatization Combined with High-Performance Liquid Chromatography–Fluorescence Detection for the Determination of Semicarbazide in Fish and Bread Samples

Semicarbazide (<b>1</b>) is a widespread genotoxic food contaminant originating as a metabolic byproduct of the antibiotic nitrofurazone used in fish farming or as a thermal degradation product of the common flour additive azodicarbonamide. The goal of this study is to develop a simple and sensitive high-performance liquid chromatography coupled with fluorescence detection (HPLC–FLD) method for the detection of compound <b>1</b> in food products. In comparison to existing methods for the determination of compound <b>1</b>, the reported method combining online precolumn derivatization and HPLC–FLD is less labor-intensive, produces higher sample throughput, and does not require the use of expensive analytical instruments. After validation of accuracy and precision, this method was applied to determine the amount of compound <b>1</b> in fish and bread samples. Comparative studies using an established liquid chromatography coupled with tandem mass spectrometry method did not yield systematically different results, indicating that the developed HPLC–FLD method is accurate and suitable for the determination of compound <b>1</b> in fish and bread samples

Facile Formation of a DNA Adduct of Semicarbazide on Reaction with Apurinic/Apyrimidinic Sites in DNA

Mutagenic semicarbazide (SEM) is a hydrazine-containing food contaminant found in a wide variety of foods. Despite decades of research, the toxicity of SEM remains incompletely understood. In this study, we demonstrate for the first time that SEM reacts rapidly with apurinic/apyrimidinic sites in an endogenous DNA lesion to form covalently bonded DNA adducts <i>in vitro</i> and in bacteria. Specifically, we performed high-performance liquid chromatography with high accuracy and tandem mass spectrometry to characterize the DNA adduct formed by reacting SEM with 2′-deoxyribose and single- and double-stranded oligonucleotides containing abasic sites under physiologically relevant conditions. By analyzing the reaction mixture at different time points, the reaction kinetics of SEM with DNA was also elucidated. Moreover, by using a highly sensitive and selective liquid chromatography–tandem mass spectrometry method, we show that SEM induces the dose-dependent formation of DNA adducts in Escherichia coli. The results from our studies provide the first direct evidence suggesting that SEM may exert genotoxicity by forming covalently bonded DNA adducts

DataSheet_1_Comparing [18F]FET PET and [18F]FDOPA PET for glioma recurrence diagnosis: a systematic review and meta-analysis.docx

PurposeThe purpose of our meta-analysis and systematic review was to evaluate and compare the diagnostic effectiveness of [18F]FET PET and [18F]FDOPA PET in detecting glioma recurrence.MethodsSensitivities and specificities were assessed using the DerSimonian and Laird methodology, and subsequently transformed using the Freeman-Tukey double inverse sine transformation. Confidence intervals were computed employing the Jackson method, while heterogeneity within and between groups was evaluated through the Cochrane Q and I² statistics. If substantial heterogeneity among the studies was observed (P 50%), we conducted meta-regression and sensitivity analyses. Publication bias was assessed through the test of a funnel plot and the application of Egger’s test. For all statistical tests, except for assessing heterogeneity (P ResultsInitially, 579 publications were identified, and ultimately, 22 studies, involving 1514 patients(1226 patients for [18F]FET PET and 288 patients for [18F]FDOPA PET), were included in the analysis. The sensitivity and specificity of [18F]FET PET were 0.84 (95% CI, 0.75-0.90) and 0.86 (95% CI, 0.80-0.91), respectively, while for [18F]FDOPA PET, the values were 0.95 (95% CI, 0.86-1.00) for sensitivity and 0.90 (95% CI, 0.77-0.98) for specificity. A statistically significant difference in sensitivity existed between these two radiotracers (P=0.04), while no significant difference was observed in specificity (P=0.58).ConclusionIt seems that [18F]FDOPA PET demonstrates superior sensitivity and similar specificity to [18F] FET PET. Nevertheless, it’s crucial to emphasize that [18F]FDOPA PET results were obtained from studies with limited sample sizes. Further larger prospective studies, especially head-to-head comparisons, are needed in this issue.Systematic Review Registrationidentifier CRD42023463476</p

Quantitation of the DNA Adduct of Semicarbazide in Organs of Semicarbazide-Treated Rats by Isotope-Dilution Liquid Chromatography–Tandem Mass Spectrometry: A Comparative Study with the RNA Adduct

Semicarbazide is a widespread food contaminant that is produced by multiple pathways. However, the toxicity of semicarbazide to human health remains unclear. Using a highly accurate and sensitive isotope-dilution liquid chromatography–tandem mass spectrometry method, we identified and quantitated in this study for the first time the DNA and RNA adduct of semicarbazide in DNA/RNA isolated from the internal organs of semicarbazide-exposed rats. The analysis revealed a dose-dependent formation of the adducts in the internal organs of the semicarbazide-dosed rats and with the highest adduct levels identified in the stomach and small intestine. Furthermore, results showed significantly higher levels of the RNA adduct (4.1–7.0 times) than that of the DNA adducts. By analyzing DNA/RNA samples isolated from rat organs in semicarbazide-dosed rats at different time points postdosing, the adduct stability <i>in vivo</i> was also investigated. These findings suggest that semicarbazide could have exerted its toxicity by affecting both the transcription and translation processes of the cell

Study of Bacterial Adhesion on Biomimetic Temperature Responsive Glycopolymer Surfaces

<i>Pseudomonas aeruginosa</i> is an opportunistic pathogen responsible for diseases such as bacteremia, chronic lung infection, and acute ulcerative keratitis. <i>P. aeruginosa</i> induced diseases can be fatal as the exotoxins and endotoxins released by the bacterium continue to damage host tissues even after the administration of antibiotics. As bacterial adhesion on cell surfaces is the first step in bacterial based pathogen infections, the control of bacteria–cell interactions is a worthwhile research target. In this work, thermally responsive poly­(<i>N</i>-isopropylacrylamide) [P­(NIPAAm)] based biomimetic surfaces were developed to study the two major bacterial infection mechanisms, which is believed to be mediated by hydrophobic or lectin–carbohydrate interactions, using quartz crystal microbalance with dissipation. Although, a greater number of <i>P. aeruginosa</i> adhered to the NIPAAm homopolymer modified surfaces at temperatures higher than the lower critical solution temperature (LCST), the bacterium–substratum bond stiffness was stronger between <i>P. aeruginosa</i> and a galactose based P­(NIPAAm) surface. The high bacterial adhesion bond stiffness observed on the galactose based thermally responsive surface at 37 °C might suggest that both hydrophobic and lectin–carbohydrate interactions contribute to bacterial adhesion on cell surfaces. Our investigation also suggests that the lectin–carbohydrate interaction play a significant role in bacterial infections

Temperature-Responsive Hyperbranched Amine-Based Polymers for Solid–Liquid Separation

Temperature-responsive hyperbranched polymers containing primary amines as pendent groups have been synthesized for solid–liquid separation of kaolinite clay suspension. The effects of temperature, polymer charge density, and polymer architecture on particle flocculation have been investigated. Suspensions treated with the temperature-responsive amine-based hyperbranched polymers showed remarkable separation of the fine particles at a low polymer dosage of 10 ppm and at testing temperatures of 40 °C. In comparison to other polymers studied (linear and hyperbranched homopolymers and copolymers), the temperature-responsive amine-based hyperbranched copolymers showed better particle flocculation at 40 °C, as evidenced by the formation of a thinner sediment bed without compromising the amount of clay particles being flocculated. This superior solid–liquid separation performance can be explained by the hydrophobic interaction of PNIPAM segments on particle surfaces or the capture of additional free particles or small floc due to the exposure of buried positive charges (because of the phase separation of the hydrophilic amines and hydrophobic PNIPAM part) at temperatures above the lower critical solution temperature (LCST)

xMAP Array Microspheres Based Stem–Loop Structured Probes as Conformational Switches for Multiplexing Detection of miRNAs

We have designed and evaluated novel stem-loop-structured probes for fluorescence detection of multiple microRNA (miRNA) targets. In the initial stage, the probes are in a closed stem conformation, shielding sterically a biotin label from being accessible to a fluorescence reporter. After hybridizing with target miRNAs, the probes undergo a conformational switch, restoring accessibility of the biotin to streptavidin–phycoerythin (SA–PE) for signal readout. Apparently, the bulky nature of the reporter SA–PE facilitates shielding of the biotin label in the absence of the target, thereby the stem–loop-structured probes allow sensitive detection of unlabeled miRNA targets, and xMAP array microspheres further realize simultaneous detection of multiple analytes using one fluorescence dye, SA–PE, for final readout. Here we demonstrated a successful multiplex assay for quantitative measurement of miRNA21, miRNA222, miRNA20a, and miRNA223, which are associated with nonsmall cell lung cancer. The approach can be extended to detecting an increasing number of targets for various indications. We believe such advancements represent a significant improvement for early disease diagnosis and prognosis

Summary of the metabolic pathways related to the metabolites that changed significantly in the hyperlipidemia model.

<p>“↑” and “↓” indicate that the compound is up- and down-regulated compared with the control group.</p

PR analysis of ¹H-NMR spectra of rat liver tissues.

<p>(A): PCA analysis of the spectra of liver tissues from normal and hyperlipidemia rats (R²X=0.955, Q²=0.782). (B): Scores plot of the OPLS-DA analysis of the spectra from the liver tissues of normal and hyperlipidemia rats (R²X=0.953, R²Y=0.999, Q²=0.827). (C): Scores plot of the OPLS-DA analysis of the spectra from the liver tissues of normal, hyperlipidemia and GP-treated rats (R²X=0.955, R²Y=0.984, Q²=0.608). (D): Scores plot of the OPLS-DA analysis of the spectra from the liver tissues of normal, hyperlipidemia and Atorvastatin-treated rats (R²X=0.931, R²Y=0.945, Q²=0.544). (E): Loading plot of the OPLS-DA analysis of the spectra from the liver tissues of normal and hyperlipidemia rats. </p

Typical 600 MHz ¹H-NMR spectra of rat liver samples.

<p>1. Lipids (VLDL/LDL) 2. Leucine 3. Isoleucine 4. Valine 5.3-Hydroxybutyrate 6. Lactate 7. Alanine 8. Lysine 9. Arginine 10. Acetate 11. Proline 12. N-Acetyl glycoproteins 13. O-Acetyl glycoproteins 14. Glutamate 15. Methionine 16. Acetoacetate 17. Acetone 18. Succinate 19. Pyruvate 20. Glutamine 21. Citrate 22. Glutathione 23. Aspartate 24. Creatine 25. Phosphatidylcholine 26. Choline 27. Phosphocholine/GPC 28. TMAO 29. Taurine 30. Glucose/aminoacids resonances 31.myo–Inositol 32. Threonine 33. β-Glucose 34.α-Glucose 35. Glycogen 36. Adenosine/Inosine 37. Fumarate 38. Tyrosine 39. Phenylalanine 40. Histidine.</p