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The HCA of the similarity data and the component table were compared with the HCAs obtained by analysis of the crude NMR data. This clearly shows the limitations of multivariate data analysis and the strength of similarity calculations combined with differential NMR, especially in relation to the analysis of trace components. In fact, the spectrum is not a series of unrelated variables, but a superposition of a limited number of component spectra, and the quantities of these components were determined.Increasing evidence highlighted the metabolic associations between host and gut microbiota during infection. However, how host-gut microbiota metabolic partnership response to carbapenem-resistant Escherichia coli (CRE) infection has yet to be elucidated. In this study, we subjected the mice to a single intraperitoneal injection of CRE and studied the alterations of the small molecule metabolites derived from host-microbial co-metabolism, as well as the gut microbiome in mice, at 24 h after infection by a two-level strategy. A panel of metabolites in feces and serum, were found to alter significantly in the CRE group, including 26 joint metabolites between them. Meanwhile, the relative abundance of 14 OTUs in Firmicutes (10 OTU), Bacteroidetes (2 OTU), Actinomycetes (1 OTU), and Proteobacteria (1 OTU) were observed to change after infection. Association analyses demonstrated that 9 OTUs including six in the Firmicutes phylum, two in the Bacteroidetes phylum, and one in the Actinomycetes phylum, were associated with the changes of 49 fecal metabolites and 42 serum metabolites. The study of gut microbiota-host metabolic interactions in the early stage of the infection is expected to provide novel diagnostic methods and therapeutic strategies for CRE infection, bring innovative solutions to resolve the current challenge.The targeted analysis of free fatty acids (FFAs) is attracting interest since several years with a plenty of studies. However, most of them are devoted to the solely determination of the short-chain fatty acids (SCFAs) arising from the symbiotic gut microbiota metabolism. Recently, the FFAs analysis highlighted changes in the plasma levels of octanoic and decanoic acids (medium-chain fatty acids or MCFAs) may be associated to gastrointestinal diseases, including colorectal cancer (CRC). Then, the simultaneous quantification of both SCFAs and MCFAs could be useful to put in evidence the interconnection between microbiota and metabolic alterations during hosts' disease. To this aim, it was developed an isotopic dilution gas-chromatography coupled mass spectrometry (ID/GC-MS) method for the targeted analysis of both linear and branched FFAs (SCFAs, MCFAs, and LCFAs) in human plasma samples as specific markers for both microbiota and host metabolic alterations. In order to minimize sample manipulation procedures, an efficient, sensible and low time-consuming procedure is presented, which relies in a simple liquid-liquid extraction before the determination of underivatized free acids (FFAs) by Single Ion Monitoring (SIM) acquisition. The reached detection limits (LODs) were less than 100 μg L-1 for most of analytes, except for acetic, hexadecanoic and octadecanoic acids that showed a LOD &gt; 1 mg L-1. Methods accuracy and precision, obtained by the analysis of the FFAs mixtures showed accuracy values between 84% and 100% and precision (RSD %) between 0.1% and 12.4% at the concentration levels tested. The proposed ID/GC-MS method was applied in a case study to evaluate the FFAs as specific markers for both microbiota and host alterations in CRC patients. Obtained results highlight the advantage of present method for its rapidity, simplicity, and robustness.Methods for the analysis of cannabinoids in bio-matrices are continually being developed, to achieve a proper sensitivity required for their detection and accuracy in their quantification. The presented paper shows that the analytical sensitivity of GC-MS to THC and its metabolites in blood samples can be significantly increase by oleamide (OLA) addition to the examined sample, which evokes the matrix effect of transient character. [https://www.selleckchem.com/products/VX-770.html Ivacaftor mw] The magnitude of signal increment resulting from oleamide presence in the examined sample is the greatest for THC metabolites and depends on oleamide concentration in the examined sample. The use of transient matrix effect to increase the sensitivity of the analysis can be applied not only in QuEChERS procedure, which is applied in the described experiments, but also in other blood sample preparation methods. Evoking the transient matrix effect by means of OLA in the experimental analytical quantitation of THC and its metabolites in blood allowed to lower limit of detection (LOD) approximately by 20.5%, 87.6% and 90.1% in the case of THC, THC-OH and THC-COOH, respectively.In this work, headspace single-drop microextraction (HS-SDME) method and headspace (HS) method were developed and compared to determine methanol by gas chromatography with flame ionization detector (GC-FID). Several factors influencing extraction efficiency, such as extraction time, temperature, sample volume, stirring rate and extraction solvent were investigated and the optimal conditions could be obtained using 2.0 µL DMF as extractant, 45 °C as heating temperature, 5 min as extraction time, 6 mL sample volume and 1.5 g KCl as addition of salt. The obtained dynamic range of HS-SDME-GC-FID was from 0.05 to 2 mg·L-1 with the limit of detection (LOD) of 0.001 mg·L-1 and that of HS-GC-FID was from 10.0 to 400.0 mg L-1 with LOD of 0.5 mg·L-1. The relative standard deviations (RSD) of HS-SDME-GC-FID was 1.9% (n = 5, C = 0.005 mg·L-1), 4.8%(n = 5, C = 0.02 mg·L-1) and 3.3%(n = 5, C = 0.1 mg·L-1), then the RSD of HS-GC-FID was 4.4%(n = 5, C = 5 mg·L-1), 5.8%(n = 5, C = 20 mg·L-1) and 4.0%(n = 5, C = 40 mg·L-1). Clearly, compared with HS-GC-FID, HS-SDME-GC-FID possessed lower LOD and better reproducibility and both of them were applied to determine methanol in imported wine and the recoveries for the spiked samples were between 83.99 and 117.24%. Overall, HS-SDME approach was confirmed to be a more sensitive and efficient sample pretreatment method and could separate matrix effectively.Natural products are rather complex samples containing a large number of compounds ranging from polar to nonpolar, small molecules to macromolecules, as well as numerous homologs/analogs with quite similar structures, which create great opportunities and treasures for discovery of bioactive drugs. For the purpose of better understanding the complex natural products and controlling their qualities, powerful analytical techniques for adequately separating chemical constituents and tracking potentially bioactive components are quite essential. Here, a design concept of bidirectional β-cyclodextrin (β-CD)-modified chromatographic stationary phase toward separation of bufadienolides extracted from toad is proposed. Bufadienolides could be divided into two classes toad venom ligand (AAUBs) and toad toxin (AACBs) with remarkable differences in structures and polarity. The hydrophobic cavity of β-CD can encapsulate the steroid part of AACBs while the hydroxyls exposed on the β-CD surface have strong hydrophilic interactions with the arginine part of AACBs. Isothermal titration calorimetry and hydrogen nuclear magnetic resonance titration experiment further validate the rationality of this design. Furthermore, the β-CD-based stationary phase can be used as a hydrophilic material to construct a HILIC × RPLC 2D separation mode for the separation of AACBs, also works as a reverse phase material to construct a RPLC × RPLC 2D separation mode for the separation of AAUBs with good orthogonality. This study will open an avenue and provide a novel insight for high-efficiency two-dimensional separation of natural products.In the current study, natural cotton fiber was served as the supporter of water, and the water acted as an extractant for liquid-phase microextraction of polar components in low-polar edible oils. An in-syringe extraction device was constructed to facilitate the extraction process by simply loading a certain amount of cotton fibers between the syringe needle and the plastic syringe tube. Then, the extraction process can be conveniently conducted by pull-push the syringe plunger. It can be regarded as a new type of dynamic liquid-phase microextraction method while operated more convent. For the feasibility study, the novel in-syringe cotton fiber-supported liquid extraction (CF-SLECF-SLE) pretreatment method was applied to extract free 3-mono-chloropropane-1,2-diol (3-MCPD) in edible oils. Specifically, the cotton fibers supported a certain amount of water by successfully pulling-pushing 1 mL of water and 1 mL of HEX in/out twice, respectively. Then, 2.0 mL of diluted oil sample (containing 0.4 g oil) was loaded in and out four times for extraction, during which process 3-MCPD was extracted into the supported water. The extracted 3-MCPD was desorbed with 1 mL of ethyl acetate (EA), derivatized with trimethyl silane imidazole (TMSI), and analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS). For three different spiked edible oils, the internal standard normalized matrix effect (IS-normalized ME) values were in ranges of 96.3-104.8% with RSD being 4.3%, benefiting the accurate quantitative analysis. The limit of quantification (LOQ) was calculated to be 2 ng/g, which met the regular determination requirement of 3-MCPD in edible oils. Satisfied linearity was obtained in 2-500 ng/g, with correlation coefficients (R2) being 0.998. The relative recoveries were in the ranges of 96.9-110.5%. The intra-/inter-day RSDs were less than 8.2% and 10.2%, respectively. The proposed method provides an efficient, simple, low-cost, and easy to automate strategy for determining free 3-MCPD in edible oils.Mycobacterium tuberculosis (Mtb) senses and responds to host-derived gasotransmitters NO and CO via heme-containing sensor kinases DosS and DosT and the response regulator DosR. Hydrogen sulfide (H2S) is an important signaling molecule in mammals, but its role in Mtb physiology is unclear. We have previously shown that exogenous H2S can modulate expression of genes in the Dos dormancy regulon via an unknown mechanism(s). Here, we test the hypothesis that Mtb senses and responds to H2S via the DosS/T/R system. Using UV-Vis and EPR spectroscopy, we show that H2S binds directly to the ferric (Fe3+) heme of DosS (KDapp = 5.30 μM) but not the ferrous (Fe2+) form. No interaction with DosT(Fe2+-O2) was detected. We found that the binding of sulfide can slowly reduce the DosS heme iron to the ferrous form. Steered Molecular Dynamics simulations show that H2S, and not the charged HS- species, can enter the DosS heme pocket. We also show that H2S increases DosS autokinase activity and subsequent phosphorylation of DosR, and H2S-mediated increases in Dos regulon gene expression is lost in Mtb lacking DosS. Finally, we demonstrate that physiological levels of H2S in macrophages can induce DosR regulon genes via DosS. Overall, these data reveal a novel mechanism whereby Mtb senses and responds to a third host gasotransmitter, H2S, via DosS(Fe3+). These findings highlight the remarkable plasticity of DosS and establish a new paradigm for how bacteria can sense multiple gasotransmitters through a single heme sensor kinase.