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Xin Xiong

Publications and source records attributed to Xin Xiong.

9 recordsLinked to original sources
PubMed2026

Improved comprehensive profiling of fecal bile acids through chemical derivatization combined with HPLC-MS/MS analysis.

Bile acids (BAs) facilitate the digestion and absorption of fats and influence lipid and glucose homeostasis, making them potential therapeutic targets for obesity and related metabolic disorders. The liver and intestinal microbiota modify BAs structurally, generating diverse chemical forms and isomers. Comprehensive profiling of the BA pool is critical for understanding their key biological functions and as a therapeutic approach for related diseases. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) is usually chosen as the preferred method for BA detection due to the complex chemical structures, the wide range of actual concentrations and the complexity of fecal sample matrices. However, free BAs are difficult to ionize, resulting in low detection signals and a lack of characteristic structural fragments to assist in structural identification. In this method, the labeling reagent (2-aminoethyl) trimethylammonium (AETMA) is employed to label the carboxyl group of BAs. Compared with underivatized BAs, the detection sensitivity of unconjugated BAs was enhanced by 25-180 fold, while that of conjugated BAs increased by 6-160 fold. It also generates unique fragment ions and enhances MS response, facilitating the discovery of potential BAs. Methodological parameters were validated using 38 BAs as representatives. Through methodological validation, it was verified that the precision, recovery, matrix effect and stability parameters of the method met acceptable criteria. We also identified 61 confirmed BAs and 55 additional candidate BAs in human pooled fecal samples. It has been successfully applied to fecal BA analysis in obese populations, providing valuable insights into potential therapeutic strategies for obesity.

Tandem Mass Spectrometry↗
PubMed2006

Genetic polymorphisms of 15 STR loci of Chinese Dongxiang and Salar ethnic minority living in Qinghai Province of China.

Fifteen autosomal STRs loci were analyzed from two samples of 178 healthy unrelated autochthonous individuals of Chinese Dongxiang and Salar ethnic minority groups using a multiplex PCR system. Allele frequencies distribution and statistical parameters for all STR loci, D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA, were determined by the AmpFISTR Identifiler Kit. The observed genotype frequencies and expected of genotype frequencies were evaluated by chi(2)-test and the Fisher exact tests. chi(2)-test showed that the agreement with Hardy-Weinberg equilibrium (p>0.05) was for all studied STR loci of two populations. The data in the present study can be used greatly for routine forensic application in the region, and enrich Chinese ethnical genetic informational resources.

Alleles↗
PubMed2006

Enhanced separation of purine and pyrimidine bases using carboxylic multiwalled carbon nanotubes as additive in capillary zone electrophoresis.

This paper describes the enhanced separation of adenine (A), hypoxanthine (HX), 8-azaadenine (8-AA), thymine (T), cytosine (C), uracil (U) and guanine (G) by CZE dispersing carboxylic multiwalled carbon nanotubes (c-MWNTs) into the running buffer. The effect of important factors such as c-MWNT nanoparticle concentration, the acidity and concentration of running buffer, and separation voltage were investigated to acquire the optimum conditions. The seven purine and pyrimidine bases could be well separated within 16 min in a 35 cm effective length fused-silica capillary at a separation voltage of +8.0 kV in a 23 mM tetraborate buffer (pH 9.2) containing 8.0 x 10(-5) g/mL c-MWNTs. Under the optimal conditions, the linear ranges were of 2-250 microg/mL for A (R2 = 0.995), 3-200 microg/mL for U (R2 = 0.990) and G (R2 = 0.992), 3-250 microg/mL for T (R2 = 0.998), 2-200 microg/mL for C (R2 = 0.985) and 4-200 microg/mL for HX (R2 = 0.988) and 8-AA (R2 = 0.990). The detection limits were 0.9 microg/mL for A (S/N = 3), 2.4 microg/mL for U, 2.0 microg/mL for T, 1.5 microg/mL for C, 2.5 microg/mL for G and 3.0 microg/mL for HX and 8-AA. The proposed method was successfully applied for determining five purine and pyrimidine bases in yeast RNA.

Electrophoresis, Capillary↗
PubMed2005

One-pot multistep Bohlmann-Rahtz heteroannulation reactions: synthesis of dimethyl sulfomycinamate.

[reaction: see text] The synthesis of dimethyl sulfomycinamate, the acidic methanolysis product of the sulfomycin family of thiopeptide antibiotics, from methyl 2-oxo-4-(trimethylsilyl)but-3-ynoate is achieved in a 2,3,6-trisubstituted pyridine synthesis that proceeds with total regiocontrol in 13 steps by the Bohlmann-Rahtz heteroannulation of a 1-(oxazol-4-yl)enamine or in 12 steps and 9% yield by three-component cyclocondensation with N-[3-oxo-3-(oxazol-4-yl)propanoyl]serine and ammonia in ethanol.

Anti-Bacterial Agents↗
PubMed2005

The moonlighting protein Tsa1p is implicated in oxidative stress response and in cell wall biogenesis in Candida albicans.

Candida albicans is one of the most common fungal pathogens in humans. The cell wall is the first contact site between host and pathogen and thus is critical for colonization and infection of the host. We have identified Tsa1p, a protein that is differentially localized to the cell wall of C. albicans in hyphal cells but remains in the cytosol and nucleus in yeast-form cells. This is different from Saccharomyces cerevisiae, where the homologous protein solely has been found in the cytoplasm. We report here that TSA1 confers resistance towards oxidative stress as well as is involved in the correct composition of hyphal cell walls. However, no significant change of the cell wall composition was observed in a TSA1 deletion strain in yeast-form cells, which is in good agreement with the observation that Tsa1p is absent from the yeast-form cell wall. This indicates that Tsa1p of C. albicans might represent a moonlighting protein with specific functions correlating to its respective localization. Furthermore, the translocation of Tsa1p to the hyphal cell wall of C. albicans depends on Efg1p, suggesting a contribution of the cAMP/PKA pathway to the localization of this protein. In a strain deleted for TUP1 that filaments constitutively Tsa1p can be found in the cell wall under all conditions tested, confirming the result that Tsa1p localization to the cell wall is correlated to the morphology of C. albicans.

Candida albicans↗
PubMed2004

Stereoselective synthesis of the gamma-lactam hydrolysate of the thiopeptide cyclothiazomycin.

[reaction: see text] Bohlmann-Rahtz pyridine synthesis of a chiral nonracemic enamine and thiazolylpropynone gives a terminal-protected pyridine-containing gamma-amino acid in high optical purity in a sequential one-pot multicomponent reaction that proceeds with total control of regiochemistry and with minimal racemization. Further elaboration has established the synthesis of the gamma-lactam acidic hydrolysate of the macrocyclic thiopeptide antibiotic cyclothiazomycin, a selective renin inhibitor, in only four steps and 30% overall yield and has confirmed its structure.

Anti-Bacterial Agents↗
PubMed2003

Synthesis of dimethyl sulfomycinamate.

[reaction: see text] Dimethyl sulfomycinamate, the oxazole-thiazole-pyridine product generated in the methanolysis of the thiopeptide antibiotic sulfomycin I, is prepared in 13 steps and 8% overall yield by the Bohlmann-Rahtz heteroannulation of 1-(oxazol-4-yl)enamines and methyl 4-(trimethylsilyl)-2-oxobut-3-ynoate.

Journal Article↗
PubMedDate not supplied

A facile solution phase combinatorial synthesis of tetrasubstituted pyridines using the Bohlmann-Rahtz heteroannulation reaction.

The solution phase combinatorial Bohlmann-Rahtz reaction gives highly functionalized pyridine libraries from enamino esters and alkynones in a single synthetic step. Good product ratios and library purities were obtained in reactions catalyzed by zinc(II) bromide, the acid-catalyzed heteroannulation procedure offering considerable improvements over traditional methodology.

Journal Article↗