Mangiferin improves early porcine embryonic development by reducing oxidative stress.

Mangiferin (MGN) is primarily found in the fruits, leaves, and bark of plants of the Anacardiaceae family, including mangoes. MGN exhibits various pharmacological effects, such as protection of the liver and gallbladder, anti-lipid peroxidation, and cancer prevention. This study aimed to investigate the effects of MGN supplementation during in vitro culture (IVC) on the antioxidant capacity of early porcine embryos and the underlying mechanisms involved. Porcine parthenotes in the IVC medium were exposed to different concentrations of MGN (0, 0.01, 0.1, and 1 µM). The addition of 0.1 µM MGN significantly increased the blastocyst formation rate of porcine embryos while reducing the apoptotic index and autophagy. Furthermore, the expression of antioxidation-related (SOD2, GPX1, NRF2, UCHL1), cell pluripotency (SOX2, NANOG), and mitochondria-related (TFAM, PGC1α) genes was upregulated. In contrast, the expression of apoptosis-related (CAS3, BAX) and autophagy-related (LC3B, ATG5) genes decreased after MGN supplementation. These findings suggest that MGN improves early porcine embryonic development by reducing oxidative stress-related genes.

Microbial enhanced oil recovery (MEOR): recent development and future perspectives.

After conventional oil recovery operations, more than half of the crude oil still remains in a form, which is difficult to extract. Therefore, exploring and developing new enhanced oil recovery (EOR) technologies have always been priority research in oilfield development. Microbial enhanced oil recovery (MEOR) is a promising tertiary oil recovery technology that has received widespread attention from the global oil industry in recent years due to its environmental friendliness, simplicity of operation, and cost-effectiveness. This review presents the: principle, characteristics, classification, recent development, and applications of MEOR technology. Based on hundreds of field trials conducted worldwide, the microbial strains, nutrient systems, and actual effects used in these technologies are summarized, with an emphasis on the achievements made in the development and application of MEOR in China in recent years. These technical classifications involve: microbial huff and puff recovery (MHPR), microbial flooding recovery (MFR), microbial selective plugging recovery (MSPR), and microbial wax removal and control (MWRC). Most of them have achieved good results, with a success rate of approximately 80%. These successful cases have accumulated into rich experiential indications for the popularization and application of MEOR technology, but there are still important yet uncertain factors that hinder the industrialization of this technology. Finally, based on the extensive research and development of MEOR by the authors, especially in both laboratory and industrial large scales, the main challenges and future perspectives of the industrial application for MEOR are presented.

Novel roles of an intragenic G-quadruplex in controlling microRNA expression and cardiac function.

Simultaneous dysregulation of multiple microRNAs (miRs) affects various pathological pathways related to cardiac failure. In addition to being potential cardiac disease-specific markers, miR-23b/27b/24-1 were reported to be responsible for conferring cardiac pathophysiological processes. In this study, we identified a conserved guanine-rich RNA motif within the miR-23b/27b/24-1 cluster that can form an RNA G-quadruplex (rG4) in vitro and in cells. Disruption of this intragenic rG4 significantly increased the production of all three miRs. Conversely, a G4-binding ligand tetrandrine (TET) stabilized the rG4 and suppressed miRs production in human and rodent cardiomyocytes. Our further study showed that the rG4 prevented Drosha-DGCR8 binding and processing of the pri-miR, suppressing the biogenesis of all three miRs. Moreover, CRISPR/Cas9-mediated G4 deletion in the rat genome aberrantly elevated all three miRs in the heart in vivo, leading to cardiac contractile dysfunction. Importantly, loss of the G4 resulted in reduced targets for the aforementioned miRs critical for normal heart function and defects in the L-type Ca2+ channel-ryanodine receptor (LCC-RyR) coupling in cardiomyocytes. Our results reveal a novel mechanism for G4-dependent regulation of miR biogenesis, which is essential for maintaining normal heart function.

Clinical Efficacy of Diet Intervention Combined with Bismuth Potassium Citrate in Helicobacter pylori-Related Chronic Atrophic Gastritis.

Objective: To investigate the clinical impact of dietary intervention in combination with bismuth potassium citrate in the management of chronic atrophic gastritis (CAG) caused by Helicobacter pylori. Methods: From April 2019 to October 2022, 160 patients with newly identified Helicobacter pylori-related CAG were treated at our facility. They were split into two groups at random: the bismuth potassium citrate medication group (n = 80) and the diet intervention + bismuth potassium citrate experimental groups (n = 80). The bismuth potassium citrate treatment group was given bismuth potassium citrate capsule treatment only, and the diet intervention + bismuth potassium citrate treatment group was given diet intervention based on bismuth potassium citrate capsule. The diet intervention score, symptom score, and pathological score of the two groups were observed at baseline and after treatment, and the relationship between dietary intervention and symptoms and pathology of Helicobacter pylori-related CAG was analyzed. Results: During the baseline period, there was no discernible difference in the diet intervention score, symptom score, or pathology score between the two groups (P > .05); after the diet intervention combination treatment, the diet intervention score, diet intervention + bismuth potassium citrate experimental groups symptom score, and pathology score were considerably lower than those in the bismuth potassium citrate treated group (P < .05). Conclusions: Dietary intervention combined with bismuth potassium citrate exhibited more effective treatment than bismuth potassium citrate-only treatment in Helicobacter pylori-related CAG, which hinted us proper diet has a positive impact on improving the therapeutic efficacy of bismuth potassium citrate.

Factors Affecting Incurred Pesticide Extraction in Cereals.

This study investigated the effect of milling on the yields of incurred residues extracted from cereals. Rice, wheat, barley, and oat were soaked in nine pesticides (acetamiprid, azoxystrobin, imidacloprid, ferimzone, etofenprox, tebufenozide, clothianidin, hexaconazole, and indoxacarb), dried, milled, and passed through sieves of various sizes. The quick, easy, cheap, effective, rugged, and safe method and liquid chromatography-tandem mass spectrometry extracted and quantified the incurred pesticides, respectively. For rice and oat, the yields were higher for vortexed samples than for soaked samples. For rice, the yields improved as the extraction time increased from 1 to 5 min. The optimized method was validated based on the selectivity, limit of quantitation, linearity, accuracy, precision, and the matrix effect. For rice and barley, the average yields improved as the particle size decreased from <10 mesh to >60 mesh. For 40-60-mesh wheat and oat, all pesticides (except tebufenozide in oat) had the highest yields. For cereals, 0.5 min vortexing, 5 min extraction, and >40-mesh particle size should be used to optimize incurred pesticide extraction.

Compliance with Oral Nutritional Supplementation among Gastric Cancer Patients at Nutritional Risk: A Cross-Sectional Study.

AIMS: To explore compliance with oral nutritional supplementation (ONS) and to identify the risk factors for noncompliance among gastric cancer patients based on the health belief model (HBM). METHODS: This prospective, observational study included gastric cancer patients at nutritional risk who were prescribed ONS from July to September 2020. Demographic factors, clinical factors, ONS-related factors, social factors and variables derived from the HBM were collected. The outcome of interest was compliance with ONS, which was measured by self-reported intake of ONS. Uni- and multivariate analyses of potential risk factors for noncompliance were performed. RESULTS: A total of 162 gastric cancer patients in the preoperative and adjuvant chemotherapy periods were analyzed. The compliance rate with ONS was 24.7%. Univariate analysis identified thirteen variables as risk factors for decreased compliance. Multivariate logistic analysis indicated that ONS compliance was independently associated with the treatment period, perceived barriers to ONS, the motivation to take ONS, and the timing of taking ONS. CONCLUSION: This study showed that overall ONS compliance among gastric cancer patients was notably low. Patients in the chemotherapy treatment period who took ONS at random times each day perceived more barriers to taking ONS and had a lower level of motivation were associated with lower compliance with ONS.

Molecular Detection and Genotyping of Toxoplasma gondii from Pigs for Human Consumption in Zhejiang and Jiangsu Provinces, Eastern China.

Toxoplasma gondii infections are common in humans and animals worldwide. Ingestion of raw or undercooked meat containing tissue cysts of T. gondii is one major source of transmission of this parasite. It is important to guarantee the meat quality of China since our pork industry produces about half of the world's pork. In this study, a total of 746 pig samples were collected from Zhejiang and Jiangsu provinces in eastern China, and examined for T. gondii infection by PCR amplification targeting B1 gene. In this study, we found that 57 of 746 (7.6%) pigs were positive for B1 gene, with 8.5% (48/562) in Zhejiang province and 4.9% (9/184) in Jiangsu province, respectively. The positive DNA samples were further genotyped at 11 genetic markers, including SAG1, 5'-and 3'-SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico through PCR-restriction fragment length polymorphism (PCR-RFLP) technology. Two genotypes (ToxoDB 9 and ToxoDB 10) of T. gondii were identified by PCR-RFLP in Zhejiang province. However, both genotypes were not determined from Jiangsu province, which is speculated on the low DNA concentration and the small number of samples. These results indicate that T. gondii infection is endemic in pigs in eastern China and may raise public food safety concerns, suggesting more interventions for T. gondii-related risks are needed in the future.

[Changes of intestinal flora in children with acute lymphoblastic leukemia before and after chemotherapy]. / å„¿ç«¥æ€¥æ€§æ·‹å·´ç»†èƒžç™½è¡€ç— åŒ–ç–—å‰åŽè‚ é“èŒç¾¤å˜åŒ–ç‰¹ç‚¹.

OBJECTIVES: To examine the changes of intestinal flora in children newly diagnosed with acute lymphoblastic leukemia (ALL) and the influence of chemotherapy on intestinal flora. METHODS: Fecal samples were collected from 40 children newly diagnosed with ALL before chemotherapy and at 2 weeks, 1 month, and 2 months after chemotherapy. Ten healthy children served as the control group. 16S rDNA sequencing and analysis were performed to compare the differences in intestinal flora between the ALL and control groups and children with ALL before and after chemotherapy. RESULTS: The ALL group had a significant reduction in the abundance of intestinal flora at 1 and 2 months after chemotherapy, with a significant reduction compared with the control group (P<0.05). Compared with the control group, the ALL group had a significant reduction in the diversity of intestinal flora before and after chemotherapy (P<0.05). At the phylum level, compared with the control group, the ALL group had a significant reduction in the relative abundance of Actinobacteria at 2 weeks, 1 month, and 2 months after chemotherapy (P<0.05) and a significant increase in the relative abundance of Proteobacteria at 1 and 2 months after chemotherapy (P<0.05). At the genus level, compared with the control group, the ALL group had a significant reduction in the relative abundance of Bifidobacterium at 2 weeks, 1 month, and 2 months after chemotherapy (P<0.05); the relative abundance of Klebsiella in the ALL group was significantly higher than that in the control group at 1 and 2 months after chemotherapy and showed a significant increase at 1 month after chemotherapy (P<0.05); the relative abundance of Faecalibacterium in the ALL group was significantly lower than that in the control group before and after chemotherapy and showed a significant reduction at 2 weeks and 1 month after chemotherapy (P<0.05). The relative abundance of Enterococcus increased significantly at 1 and 2 months after chemotherapy in the ALL group (P<0.05), and was significantly higher than that in the control group (P<0.05). CONCLUSIONS: The diversity of intestinal flora in children with ALL is significantly lower than that in healthy children. Chemotherapy significantly reduces the abundance of intestinal flora and can reduce the abundance of some probiotic bacteria (Bifidobacterium and Faecalibacterium) and increase the abundance of pathogenic bacteria (Klebsiella and Enterococcus) in children with ALL.

SNHG10 Promotes Cell Proliferation and Migration in Gastric Cancer by Targeting miR-495-3p/CTNNB1 Axis.

BACKGROUND: Long non-coding RNAs have been acknowledged as the crucial regulators in the progression of human cancers, including gastric cancer (GC). Small nucleolar RNA host gene 10 (SNHG10) has been identified as an oncogene in several cancer types. Nonetheless, it is unclear whether SNHG10 exerts functions in GC cells. AIMS: The aims of the current study were to explore the function and underlying mechanism of SNHG10 in GC. METHODS: The expression levels of SNHG10, miR-495-3p and catenin beta 1 (CTNNB1) were detected by RT-qPCR. Loss-of-function assays, including CCK-8, colony formation assay, flow cytometry analysis and transwell assays, were conducted to verify the effect of SHNG10 on the proliferation, apoptosis, migration and invasion of GC cells. Mechanism experiments were performed to identify the downstream molecular mechanism of SNHG10. RESULTS: SNHG10 was expressed at a high level in GC cells. Knockdown of SNHG10 inhibited the proliferation, migration and invasion of GC cells. Silencing of SNHG10 led to the downregulation of core factors of WNT signaling pathway. Knockdown of SNHG10 could decline the expression of CTNNB1 through sequestering miR-495-3p. CONCLUSIONS: SNHG10 promotes the procession of GC through targeting miR-495-3p/CTNNB1 and activating WNT signaling pathway.

Single-cell analyses reveal functional classification of dendritic cells and their potential roles in inflammatory disease.

Dendritic cells (DCs) have crucial roles in immune-related diseases. However, it is difficult to explore DCs because of their rareness and heterogeneity. Although previous studies had been performed to detect the phenotypic characteristics of DC populations, the functional diversity has been ignored. Using a combination of flow cytometry, single-cell quantitative PCR, and bioinformatic analysis, we depicted the DC panorama with not only phenotypic but also functional markers. Functional classification of DCs in mouse lymphoid tissue (spleen) and nonlymphoid tissue (liver) was performed. The results revealed that expression of macrophage scavenger receptor 1 ( MSR1) and C-C motif chemokine receptors ( CCR) 1, CCR2, and CCR4 were elevated in liver DCs, suggesting increased lipid uptake and migration abilities. The enriched expression of costimulatory molecule CD80, TLR9, and TLR adaptor MYD88 in spleen DCs indicated a more-mature phenotype, enhanced pathogen recognition, and T-cell stimulation abilities. Furthermore, we compared DCs in the atherosclerotic mouse models with healthy controls. In addition to the quantitative increase in DCs in the liver and spleen of the apolipoprotein E-knockout ( ApoE-/-) mice, the functional expression patterns of the DCs also changed at the single-cell level. These results promote our understanding of the participation of DCs in inflammatory diseases and have potential applications in DC clinical assessment.-Shi, Q., Zhuang, F., Liu, J.-T., Li, N., Chen, Y.-X., Su, X.-B., Yao, A.-H., Yao, Q.-P., Han, Y., Li, S.-S., Qi, Y.-X., Jiang, Z.-L. Single-cell analyses reveal functional classification of dendritic cells and their potential roles in inflammatory disease.

The influence of image quality on diagnostic performance of a machine learning-based fractional flow reserve derived from coronary CT angiography.

OBJECTIVE: To investigate the effect of image quality of coronary CT angiography (CCTA) on the diagnostic performance of a machine learning-based CT-derived fractional flow reserve (FFRCT). METHODS: This nationwide retrospective study enrolled participants from 10 individual centers across China. FFRCT analysis was performed in 570 vessels in 437 patients. Invasive FFR and FFRCT values ≤ 0.80 were considered ischemia-specific. Four-score subjective assessment based on image quality and objective measurement of vessel enhancement was performed on a per-vessel basis. The effects of body mass index (BMI), sex, heart rate, and coronary calcium score on the diagnostic performance of FFRCT were studied. RESULTS: Among 570 vessels, 216 were considered ischemia-specific by invasive FFR and 198 by FFRCT. Sensitivity and specificity of FFRCT for detecting lesion-specific ischemia were 0.82 and 0.93, respectively. Area under the curve (AUC) of high-quality images (0.93, n = 159) was found to be superior to low-quality images (0.80, n = 92, p = 0.02). Objective image quality and heart rate were also associated with diagnostic performance of FFRCT, whereas there was no statistical difference in diagnostic performance among different BMI, sex, and calcium score groups (all p > 0.05, Bonferroni correction). CONCLUSIONS: This retrospective multicenter study supported the FFRCT as a noninvasive test in evaluating lesion-specific ischemia. Subjective image quality, vessel enhancement, and heart rate affect the diagnostic performance of FFRCT. KEY POINTS: • FFRCTcan be used to evaluate lesion-specific ischemia. • Poor image quality negatively affects the diagnostic performance of FFRCT. • CCTA with ≥ score 3, intracoronary enhancement degree of 300-400 HU, and heart rate below 70 bpm at scanning could be of great benefit to more accurate FFRCTanalysis.

Umpolung Strategy for the Synthesis of Chiral Dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles.

Based on a novel umpolung strategy, an efficient and highly enantioselective cascade aldol/cyclization/tautomerization of the 2-(2-oxoindolin-3-yl)malononitrile to active carbonyl compounds with excellent diastereo- and enantioselectivity has been developed. Also, various enantio-enriched multifunctional dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles with adjacent spiro-stereocenters were conveniently obtained by this novel methodology. Also, the dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles were easily transformed into structurally complex molecules without any effect on the diastereo- and enantioselectivity.

Extracellular Electron Shuttling Mediated by Soluble c-Type Cytochromes Produced by Shewanella oneidensis MR-1.

How metal-reducing bacteria transfer electrons during dissimilatory energy generation under electron acceptor-limited conditions is poorly understood. Here, we incubated the iron and manganese-reducing bacterium Shewanella oneidensis MR-1 without electron acceptors. Removal of soluble extracellular organic compounds (EOCs) dramatically retarded transfer of electrons to an experimental electron acceptor, Cr(VI), by MR-1. However, the return of either high MW (>3000 Da) or low MW (<3000 Da) soluble EOCs produced by MR-1 to washed cells restored Cr(VI) reduction though Cr(VI) reduction was fastest when both size fractions were added together. Spectral and electrochemical characterization of EOCs indicated the presence of flavins and c-type cytochromes (c-Cyts). A model of the kinetics of individual elementary reactions between cells, flavins, released c-Cyts, and Cr(VI), including the direct reduction of flavins, released c-Cyts, and Cr(VI) by cells and the indirect reduction of Cr(VI) by reduced forms of flavins and released c-Cyts, was developed. Model results suggest that released c-Cyts could act as electron mediators to accelerate electron transfer from cells to Cr(VI), and the relative contribution of this pathway was higher than that mediated by flavins. Hence, extracellular c-Cyts produced by MR-1 likely play a role in extracellular electron transfer under electron acceptor-limited conditions. These findings provide new insights into extracellular electron shuttling and the metabolic strategy of metal-reducing bacteria under electron acceptor-limited conditions.

Antioxidant and Compositional HPLC Analysis of Three Common Bamboo Leaves.

Bamboo leaves of Phyllostachys nigra (PN), Lophatherum gracile (LG), and Pleioblastus amarus (PA) are three common herbs in China. In this work, a new high performance liquid chromatography (HPLC) method for the simultaneous determination of seven compounds in bamboo leaves has been developed; and PN, LG, and PA leaves were analyzed. PN showed four times as much chlorogenic acid (CA) than the other two, and contained the most isoorientin (iso-ORI) and isovitexin (iso-VIT) as well. The PA presented the most orientin (ORI) and LG covered a majority of cynaroside (CYN). We measured the antioxidant activity by scavenging the stable 2,2-diphenyl-1-pyridinohydrazinyl (DPPH) free radicals, and found that Luteolin (inhibitory concentration (IC)50 = 0.42 µM, LUT) and CYN (IC50 = 0.43 µM) showed 2-3 times higher antioxidant activity than iso-ORI (IC50 = 0.81 µM), ORI (IC50 = 0.84 µM), and other related antioxidant standards such as trolox (IC50 = 0.97 µM) and ascorbic acid (IC50 = 0.93 µM, VC). Among extracts, PN and PA showed considerable antioxidant activity, which was related well with the contents of CA, iso-ORI, and iso-VIT (p < 0.05). This study firstly provides evidence for functional antioxidant compounds of bamboo leaves based on statistical analysis of the HPLC analysis and DPPH assay, and it lays a foundation for its further development or utilization.

Platelet-derived microparticles promote endothelial cell proliferation in hypertension via miR-142-3p.

Endothelial cells (ECs) are located at the interface between flowing blood and the vessel wall, and abnormal EC proliferation induced by pathologic environments plays an important role in vascular remodeling in hypertensive conditions. Exchanges of information between blood components and ECs are important for EC function. Hence, the present study sought to determine how platelets induce EC dysfunction under hypertensive conditions. EC proliferation was increased in renal hypertensive rats established by abdominal aortic coarctation compared with control rats and that elevated thrombin in plasma promoted platelet activation, which may induce the release of platelet-derived microparticles (PMPs). MicroRNA (MiR) array and qPCR revealed a higher level of miR-142-3p in platelets and PMPs. In vitro, PMPs delivered miR-142-3p into ECs and enhanced their proliferation via Bcl-2-associated transcription factor (BCLAF)1 and its downstream genes. These results indicate that PMPs deliver miR-142-3p from activated platelets into ECs and that miR-142-3p may play important roles in EC dysfunction in hypertensive conditions and may be a novel therapeutic target for maintaining EC homeostasis in hypertension.-Bao, H., Chen, Y.-X., Huang, K., Zhuang, F., Bao, M., Han, Y., Chen, X.-H., Shi, Q., Yao, Q.-P., Qi, Y.-X. Platelet-derived microparticles promote endothelial cell proliferation in hypertension via miR-142-3p.

[Design and exploration of genetic experiments for non-Mendelian segregation].

It has always been a challenge to combine research progress with undergraduate laboratory teaching. Herein we designed a comprehensive experiment to compare classical Mendelian segregation and non-Mendelian distorted segregation by utilizing a rice material (DSSL) containing F1 hybrid male sterility locus S23 constructed previously in our research project. Using the four SSR markers located on two chromosomes of rice, the genotypes of the F2 population and the two parents were analyzed, and the phenotypes of the pollen fertility of the two parents and their F1 plants were investigated. The results not only verified segregation law at the molecular level, but also fully demonstrated the distorted segregation in both genotypes and phenotypes, thus deepening students' understandings of plant genetics and the relationship between genotypes and phenotypes, inspiring students' interests in genetics experiments, and enhancing students' consciousness and enthusiasm for experimental learning. On the basis of this, a sustainable development idea of transforming scientific research progress into teaching applications was conceived to promote the reform and innovation of genetics laboratory teaching.

Cyclic stretch induces VEGFA alternative splicing via Serine/Arginine-Rich Splicing Factor 1.

Abnormal proliferation of vascular smooth muscle cells (VSMCs) induced by high cyclic stretch is crucial in the vascular remodeling during hypertension. Vascular endothelial growth factor A (VEGFA) alternative splicing plays important roles in the pathological process of vascular diseases and remodeling. However, the roles of VEGFA isoforms in modulating VSMC functions in response to cyclic stretch remain unclear. We hypothesize that high cyclic stretch may induce VEGFA alternative splicing via Serine/arginine-rich splicing factor 1 (SRSF1) which subsequently induce VSMC proliferation. In the present research, hypertensive rat model was established using the abdominal aortic constriction method. In comparison with sham-operated group, immunohistology staining showed translocation of SRSF1 into nuclei in hypertensive rat thoracic aorta, and RT-PCR detected a shift of VEGFA expression pattern, including the increased expression of VEGFA120 and VEGFA164, but not VEGFA188.Then VSMCs were subjected to cyclic stretch in vitro using a Flexercell strain unit. VEGFA ELISA assay showed 15% cyclic stretch increased the secretion of VEGFA which significantly increased proliferation of VSMCs. Western blot and immunofluorescence detected accumulation of SRSF1 in nuclei after 15% cyclic stretch application. Furthermore, SRSF1-specific siRNA transfection reversed the VEGFA secretion induced by pathological high cyclic stretch. Our present results suggested that pathologically high cyclic stretch induces the shuttling of SRSF1 which results in the secretive pattern splicing of VEGFA and finally contributes to the proliferation of VSMCs.

Production of Hydrogen Peroxide in Groundwater at Rifle, Colorado.

The commonly held assumption that photodependent processes dominate H2O2 production in natural waters has been recently questioned. Here, we present evidence for the unrecognized and light-independent generation of H2O2 in groundwater of an alluvial aquifer adjacent to the Colorado River near Rifle, CO. In situ detection using a sensitive chemiluminescent method suggests H2O2 concentrations ranging from lower than the detection limit (<1 nM) to 54 nM along the vertical profiles obtained at various locations across the aquifer. Our results also suggest dark formation of H2O2 is more likely to occur in transitional redox environments where reduced elements (e.g., reduced metals and NOM) meet oxygen, such as oxic-anoxic interfaces. A simplified kinetic model involving interactions among iron, reduced NOM, and oxygen was able to reproduce roughly many, but not all, of the features in our detected H2O2 profiles, and therefore there are other minor biological and/or chemical controls on H2O2 steady-state concentrations in such aquifer. Because of its transient nature, the widespread presence of H2O2 in groundwater suggests the existence of a balance between H2O2 sources and sinks, which potentially involves a cascade of various biogeochemically important processes that could have significant impacts on metal/nutrient cycling in groundwater-dependent ecosystems, such as wetlands and springs. More importantly, our results demonstrate that reactive oxygen species are not only widespread in oceanic and atmospheric systems but also in the subsurface domain, possibly the least understood component of biogeochemical cycles.

Simultaneous quantification of imatinib and its main metabolite N-demethyl-imatinib in human plasma by liquid chromatography-tandem mass spectrometry and its application to therapeutic drug monitoring in patients with gastrointestinal stromal tumor.

The aim of this study was to improve and validate a more stable and less time-consuming method based on liquid chromatography and tandem mass spectrometry (LC- MS/MS) for the quantitative measurement of imatinib and its metabolite N-demethyl-imatinib (NDI) in human plasma. Separation of analytes was performed on a Waters XTerra RP18 column (50 × 2.1 mm i.d., 3.5 µm) with a mobile phase consisting of methanol-acetonitrile-water (65:20:15, v/v/v) with 0.05% formic acid at a flow-rate of 0.2 mL/min. The Quattro MicroTM triple quadruple mass spectrometer was operated in the multiple-reaction-monitoring mode via positive electrospray ionization interface using the transitions m/z 494.0 → 394.0 for imatinib, m/z 479.6 → 394.0 for NDI and m/z 488.2 → 394.0 for IS. The method was linear over 0.01-10 µg/mL for imatinib and NDI. The intra- and inter-day precisions were all <15% in terms of relative standard deviation, and the accuracy was within ±15% in terms of relative error for both imatinib and NDI. The lower limit of quantification was identifiable and reproducible at 10 ng/mL. The method was sensitive, specific and less time-consuming and it was successfully applied in gastrointestinal stromal tumor patients treated with imatinib.

Iron-Mediated Oxidation of Methoxyhydroquinone under Dark Conditions: Kinetic and Mechanistic Insights.

Despite the biogeochemical significance of the interactions between natural organic matter (NOM) and iron species, considerable uncertainty still remains as to the exact processes contributing to the rates and extents of complexation and redox reactions between these important and complex environmental components. Investigations on the reactivity of low-molecular-weight quinones, which are believed to be key redox active compounds within NOM, toward iron species, could provide considerable insight into the kinetics and mechanisms of reactions involving NOM and iron. In this study, the oxidation of 2-methoxyhydroquinone (MH2Q) by ferric iron (Fe(III)) under dark conditions in the absence and presence of oxygen was investigated within a pH range of 4-6. Although Fe(III) was capable of stoichiometrically oxidizing MH2Q under anaerobic conditions, catalytic oxidation of MH2Q was observed in the presence of O2 due to further cycling between oxygen, semiquinone radicals, and iron species. A detailed kinetic model was developed to describe the predominant mechanisms, which indicated that both the undissociated and monodissociated anions of MH2Q were kinetically active species toward Fe(III) reduction, with the monodissociated anion being the key species accounting for the pH dependence of the oxidation. The generated radical intermediates, namely semiquinone and superoxide, are of great importance in reaction-chain propagation. The kinetic model may provide critical insight into the underlying mechanisms of the thermodynamic and kinetic characteristics of metal-organic interactions and assist in understanding and predicting the factors controlling iron and organic matter transformation and bioavailability in aquatic systems.