The Association of High Lipoprotein(a) Concentration and Risk of Ischaemic Stroke in Atrial Fibrillation Patients.

Background: Lipoprotein(a) [Lp(a)] is a well-established risk factor for ischaemic stroke (IS). It is unclear whether Lp(a) is associated with IS in patients with atrial fibrillation (AF). The aim of this study is to explore the association between the concentration of Lp(a) and the risk of IS in AF patients, hope to find the potential risk factor for the IS in AF patients. Methods: This study is a retrospective cohort study. The screened AF patients between January 2017 and July 2021 were matched at 1:1 by the propensity score matching (PSM) method in the Second Affiliated Hospital of Nanchang University. Associations between Lp(a) and ischaemic stroke were analysed using logistic regression models, stratified analysis and sensitivity analysis. Statistical analyses were conducted using IBM SPSS software. Results: The number of enrolled participates is 2258, which contains 1129 non-AF patients and 1129 AF patients. Among IS patients, the median Lp(a) concentration was higher than that of controls (17.03 vs. 15.36 mg/dL, P = 0.032). The Spearman rank-order correlation coefficients revealed significant positive relationships between IS and Lp(a) (P = 0.032). In addition, a significant increase in IS risk was associated with Lp(a) levels >30.00 mg/dL in unadjusted model [OR:1.263, 95% CI(1.046-1.523), P = 0.015], model 1 [OR:1.284, 95% CI(1.062,1.552), P = 0.010], model 2 [OR: 1.297, 95% CI(1.07,1.573). P = 0.008], and model 3 [OR: 1.290, 95% CI (1.064, 1.562). P = 0.009]. The stratified analysis indicated that this correlation was not affected by female sex [1.484 (1.117, 1.972), P = 0.006], age ≤ 60 [1.864 (1.067-3.254), P=0.029], hypertension [1.359 (1.074, 1.721), P = 0.011], or non-coronary heart disease (CHD) [1.388 (1.108, 1.738), P = 0.004]. Conclusion: High levels of Lp(a) were significantly related to IS in AF patients and may be a potential risk factor in the onset of an IS in AF patients.

LC-MS/MS Quantitation of Formaldehyde-Glutathione Conjugates as Biomarkers of Formaldehyde Exposure and Exposure-Induced Antioxidants: A New Look on an Old Topic.

Humans are continuously exposed to formaldehyde via both endogenous and exogenous sources. Prolonged exposure to formaldehyde is associated with many human diseases, such as lung cancer and leukemia. The goal of this study is to develop biomarkers to measure formaldehyde exposure, which could be used to predict the risk of associated diseases. As glutathione (GSH) is well-known for its crucial role in the detoxification of a wide variety of xenobiotics, including formaldehyde, we rigorously quantitated in this study the conjugates formed when formaldehyde reacted with GSH using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) coupled with an isotope dilution method. The results showed for the first time that (S)-1-(((R)-2-amino-3-(carboxymethylamino)-3-oxopropylthio)methyl)-5-oxopyrrolidine-2-carboxylic acid (PGF) and thioproline-glycine (SPro-Gly) are major metabolites in both nonenzymatic reactions and formaldehyde-exposed human cells. In particular, over 35% of the formaldehyde from external sources was found to convert to SPro-Gly in the exposed cells. Interestingly, data showed that these exposure-induced adducts exhibited good antioxidative properties, which can protect cells from hydrogen peroxide mediated oxidative insult. It is anticipated that the findings of this study could shed light on developing PGF and SPro-Gly as dietary supplements and on the development of noninvasive methods to assess health risks associated with formaldehyde exposure.

Analysis of aristolochic acids in Houttuynia cordata by liquid chromatography-tandem mass spectrometry.

Houttuynia cordata (H. cordata) is a popular vegetable in Asian countries and is also used extensively as herbal medicine in treating various diseases. H. cordata contains aristolactams, which have a similar Chinese name as aristolochic acids (AAs); hence, an emerging concern in the greater China region has arisen about the potential linkage between H. cordata and aristolochic acid nephropathy (AAN). However, only a single study has tested for the presence of AAs in H. cordata samples, and the analysis was limited by the analytical sensitivity of the method. Thus, further analysis of AAs in H. cordata using analytical method of higher sensitivity is needed to alleviate public anxiety over the use of this popular vegetable. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was used to analyze H. cordata samples for the natural existence of aristolochic acid I (AA-I) and aristolochic acid II (AA-II), which are the most carcinogenic and nephrotoxic compounds in the AA family. After evaluating the method performance by fortifying blank samples with three concentrations of AAs, the validated method was applied to identify AA-I and AA-II in both fresh and sun-dried H. cordata samples (n = 20) collected from different cities in China. The LC-MS/MS method achieved method detection limits (MDLs) as low as 2 ng/g of AAs in H. cordata. Analysis of the collected fresh and sun-dried H. cordata samples revealed that AA-I and AA-II either do not exist naturally in H. cordata or exist at concentrations below the MDLs. Therefore, it is not very likely that consumption of H. cordata will result in AAN because AA-I and AA-II, the nephrotoxic and carcinogenic culprits of AAN, are not produced naturally in the plant or are produced at levels that do not pose a risk of AAN.

LC-MS/MS Coupled with a Stable-Isotope Dilution Method for the Quantitation of Thioproline-Glycine: A Novel Metabolite in Formaldehyde- and Oxidative Stress-Exposed Cells.

Formaldehyde (FA) is a human carcinogen that is ubiquitous in the ambient environment and also generated endogenously in oxidatively stressed cells. There is accumulated evidence that FA is an etiological agent of leukemia development in humans. To develop a biomarker for FA exposure, we have, in this study, developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with stable isotope-dilution method to explore the reactivity of FA with glutathione (GSH) in physiologically relevant conditions. Interestingly, analysis of the reaction mixture by LC-MS/MS revealed exposure concentration- and duration-dependent formation of thioproline-glycine (SPro-Gly) produced by reaction of FA with cysteinyl-glycine (Cys-Gly) as a novel metabolite. Furthermore, dose-dependent formation of the thioproline adduct was observed in human cells separately exposed to FA and Fe2+-EDTA, a hydroxyl radical source. To the best of our knowledge, this is the first study reporting a thiazolidine carboxylic acid formed by reaction of FA and Cys-Gly is a major metabolite of FA. The results suggest a variety of GSH-derived thiazolidine metabolites may serve as potential biomarkers for FA and oxidative stress exposure, and the developed LC-MS/MS method provides a means for accurate determination of SPro-Gly as a dosimeter of oxidative stress and formaldehyde exposure.

Determination and elimination of hazardous pollutants by exploitation of a Prussian blue nanoparticles-graphene oxide composite.

The exploitation of desired materials with specific properties for water remediation has become an irresistible trend. Generally, materials favorable to the elimination of hazardous contaminants are always beneficial to the detection of these compounds. Nevertheless, few researches combined these two procedures into a treating line. Therefore, a Prussian blue nanoparticles-doped graphene oxide (PBGO) composite was successfully synthesized and prepared as a solid-phase microextraction (SPME) coating for pollutant detection and a three-dimensional (3D) aerogel for contaminant removal in this study. Owing to its highly conjugated structure, abundant oxygen sites and periodical cyano groups, the composite achieved satisfactory enrichment capacity towards specific pollutants. The combination of elimination and determination of organic contaminants by using the PBGO composite not only possessed satisfactory performance but also avoided the separation process and secondary pollution. Finally, the PBGO SPME coating was utilized for the sensitive detection of several hazardous contaminants in environmental water samples with satisfactory recoveries. We think the combination of a PBGO composite with the green sample pretreatment technique (SPME) and pollutant elimination will not only help to facilitate the improvement in analytical fields, but also provide a secondary pollution-free way to explore the adsorption properties of adsorptive materials for environmental contaminants.

A tri-metal centered metal-organic framework for solid-phase microextraction of environmental contaminants with enhanced extraction efficiency.

This study presents the preparation and the characterizations of six tri-metal centered metal-organic frameworks (tM-MOFs) as solid-phase microextraction (SPME) adsorbents. Possessing different proportions of Al, Ga and In atoms in their frameworks, the tM-MOF-based SPME coatings exhibited different extraction performance towards the organic pollutants. Extraction results showed that the M4 (Al0.593Ga0.167In0.240(O2C2H4)(h2fipbb)) coating exhibited the best enrichment ability among six tM-MOFs. In addition, it showed better extraction efficiency towards the analytes than three single-metal centered MOFs coatings and a commercial polydimethylsiloxane (PDMS) coating. The adsorption process of the M4 coating was physical adsorption and it was mainly affected by the diffusion process of the compound from the sample to the material, which is the same with the adsorption processes of the single-metal centered MOFs coatings. Under optimal conditions (extraction time, 3 min; NaCl concentration, 25% (w/v); desorption temperature, 270 °C; extraction temperature, 30 °C), the M4 coating achieved low detection limits (0.13-0.88 ng L-1) and good linearity (5-2000 and 5-5000 ng L-1) for benzene series compounds. The repeatabilities (n = 5) for single fiber were between 4.3 and 8.1%, while the reproducibilities (n = 3) of fiber-to-fiber were in the range of 7.9-12.7%. Finally, a M4 coated SPME fiber was successfully applied to the analysis of environmental water samples with satisfactory recoveries (80.8%-119.5%).