Publications by authors named "Xian-feng Chen"

A novel sample preparation method based on polarity grouping was developed for the comprehensive determination of 315 undesirable low-weight organic pollutants ranging from polar to weakly polar in wolfberry. The method involves the swelling of the sample in ammonium acetate buffer, two-phase extraction, three-phase extraction, and dispersive solid phase extraction (D-SPE) with the assistance of low-temperature centrifugation and analysis by ultrahigh performance liquid chromatography coupled with electrospray ionization tandem mass (UHPLC-ESI-MS-MS) by using the multiple reaction monitoring mode. The recoveries of the analytes with wide range of polarity were satisfactory.

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A generic, rapid, simple and low-cost analytical method for simultaneously screening and confirming 400 veterinary drugs and other contaminants in raw honey was developed. The method was based on one-step extraction and ultra-high performance liquid chromatography coupled with electrospray ionization and tandem mass spectrometry. A well-designed extraction method results in the complete precipitation of proteins and separation of analytes from carbohydrates and reduces the time and cost of analysis by covering polar to non-polar analytes.

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A rapid, simple, and generic analytical method for the simultaneous determination of 140 undesirable low-weight pesticides and mycotoxins from different chemical classes in black tea was developed. The method involved swelling the sample in ammonium acetate buffer, extraction with acetonitrile-dimethyl sulfoxide, cleanup by dual dispersive solid-phase extraction (D-SPE) with the assistance of low-temperature centrifugation, and analysis by ultraperformance liquid chromatography coupled with electrospray ionization tandem mass spectrometry using multiple reaction monitoring mode. The interferences in the extract were eliminated by the combination of dual d-SPE using only C sorbent and anhydrous magnesium sulfate, which maintained the chromatographic column under the ideal condition for a long time and enabled satisfactory recoveries of hydrophobic and hydrophilic analytes simultaneously.

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A rapid, simple, and generic analytical method that could simultaneously determine 291 undesirable low molecular weight chemical contaminants from different drug families in protein powder, such as veterinary drugs and pesticides, etc, had been developed. This method comprised the extraction with acetonitrile-dimethyl sulfoxide (DMSO), clean-up through dispersive solid phase extraction (D-SPE) and low temperature filtration, and analysis by ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry at multiple-reaction monitoring mode. Acetonitrile-DMSO was more generic than acetonitrile or methanol for the extraction of large-scale organic chemical contaminants with different polarities in protein powder.

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In this work, the cascaded second-order spontaneous parametric down-conversion (SPDC) is considered to produce pure state photon triplets in periodically poled lithium niobite (PPLN) doped with 5% MgO. A set of parameters are optimized through calculating the Schmidt number of two-photon states generated by each down-conversion process with different pump durations and crystal lengths. We use a Gaussian filter in part and obtain three photons with 100% purity in spectrum.

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Abbe diffraction limit has always been an important subject in conventional far-field focusing and imaging systems, where the resolution of an image is usually limited to 0.5λ/NA. Recently, the studies of the optical super-oscillation lens (SOL) enable us to break the limitation in both theory and practice successfully.

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Acute lung injury (ALI) is a common clinical syndrome in ICU departments with high mortality. The pathology of ALI is still not clear and there is no specific and efficient treatment against ALI. In this study, we established ALI rat model through lipopolysaccharide administration.

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The objective of the present study was to evaluate image quality and radiation dosage using a low-dose prospectively electrocardiogram (ECG)-gated computed tomography (CT) protocol for dual-source angiography in children with complex congenital heart disease. A total of 206 patients with complex congenital heart disease were equally assigned into two groups at random. The children in group A underwent low-dose retrospective ECG-gated CT scanning with an ECG-pulsing technique, and group B underwent prospective ECG-gated scanning with an ECG-pulsing technique.

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BACKGROUND The aim of this study was to compare the hemodynamic changes in 2 different cannulations in portal system (portal venous catheterization and splenic venous catheterization) during venovenous bypass (VVB) of swine orthotopic liver transplantation (OLT) MATERIAL AND METHODS Thirty pairs (a total of 60) of healthy Duroc pigs were selected for OLT. According to the difference of cannulation in portal venous system during VVB, these pigs were divided into 2 groups: the PVC group (pigs with portal venous catheterization, n=15) and the SVC group (pigs with splenic venous catheterization, n=15). Intraoperative hemodynamic parameters were monitored continuously.

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Objective And Design: Our study aimed to determine the effect of mild hypothermia (MHT) on the expression of toll-like receptor 2 (TLR2) in lung tissue with acute lung injury. The animals were randomly divided into control, model and mild hypothermia groups.

Methods: A total of 40 rats was used in the study.

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Objective: To investigate the mRNA and protein expression of FK506-binding protein 52 (FKBP52) in the chorionic villi of patients with recurrent spontaneous abortion (RSA) and normal women during early pregnancy.

Methods: Fresh chorionic villus tissues were collected from 60 subjects. A total of 30 patients with a history of RSA were enrolled into the RSA group and 30 normal pregnant women were enrolled into the control group.

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Objective: Daptomycin, a cyclic lipopeptide that exhibits rapid, concentration-dependent bactericidal activity in vitro against a broad spectrum of Gram-positive pathogens, has now, since 2003, been approved in more than 70 countries and regions to treat skin and soft-tissue infections (SSTIs). The purpose of this meta-analysis was to compare the safety and efficacy of daptomycin with other antibiotics, especially with vancomycin which has long been considered the standard therapy for complicated SSTIs.

Design: Meta-analysis of randomised controlled trials (RCTs).

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Theoretical investigation on the group velocity control of ultrafast pulses through quadratic cascading nonlinear interaction is presented. The dependences of the fractional time delay as well as the quality factor of the delayed femtosecond pulse on the peak intensity, group velocity mismatch, wave-vector mismatch and the pulse duration are examined. The results may help to understand to what extent some optical operation parameters could have played a role in controlling the ultrashort pulses.

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Objective: To explore the effects of HBsAg pulsed dendritic vaccination on anti-HBs production in immunosuppressed rats after liver transplantation (LT).

Methods: Brown-Norway liver allografts were transplanted into Lewis recipients. The transplanted Lewis rats were injected with EK506 (2 mg/kg) and randomly divided into two groups: rats in HBsAg-DCs group (n = 15) were intraperitoneally injected with HBsAg pulsed DCs at 14 d and 28 d after LT, and rats in the HBsAg group (n = 15) were injected with HBsAg (200 mul) once a week for 12 weeks.

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Background: Several experimental studies have observed better outcomes after glycine treatment in patients with endotoxin-induced liver injuries, but its molecular mechanism is not yet fully understood. The purpose of this study was to evaluate the hypothesis that glycine attenuates endotoxin-induced liver injury by affecting endotoxin signal transduction in liver macrophages.

Methods: An animal model of endotoxin-induced liver injury was established by intraperitoneally injecting mice with 10 mg/kg body weight endotoxin fed a pretreatment diet with or without 5% (w/w) glycine.

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Background: Endotoxin tolerance (ET) is an important mechanism to maintain the homeostasis of Kupffer cells (KCs), because KCs are continually exposed to various pathogen-associated molecular patterns including lipopolysaccharide (LPS). ET involves multiple changes in cell signal transduction pathways; however, not all signaling pathways are down-regulated and some proteins are up-regulated. The latter proteins may be counter regulatory, including interleukin-1 receptor-associated kinase M (IRAK-M) expression.

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Objective: To explore the protective mechanisms of glycine (Gly) on lipopolysaccharides (LPS) induced liver injury.

Methods: BABL/c mice were randomly divided into a LPS group, in which the animals were intraperitoneally injected with 10 mg/kg LPS, and a Gly group, in which the mice were pretreated with a 5% Gly-containing diet for 3 days before receiving the same dose of LPS. The livers of the mice were examined for histopathological changes.

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Objective: To explore the possible mechanism and optimal treatment phase of glycine for inhibition lipopolysaccharide (LPS) induced Kupffer cells (KCs) activation.

Methods: The KCs were isolated from 40 BALB/c mice and divided into four groups: the endotoxin group, the prevention group, the early treatment group and the later treatment group (n = 10). The endotoxin group was treated with 10 mg/L LPS, and in the other three groups, glycine (1 mmol/L) was given 24 h before, or at 0 h or 4 h respectively after LPS stimulation.

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Objective: To explore the mechanism of endotoxin tolerance (ET) through observing the expression of interleukin 1 receptor associated kinase-4 (IRAK-4) during endotoxin tolerance development in Kupffer cells (KCs).

Methods: Isolated KCs of Balb/c mouse were divided into two groups: the non-endotoxin tolerance (NET) group and the endotoxin tolerance (ET) group, which were pretreated with 10 ng/ml lipopolysaccharide (LPS) for 24 h. Then, the two groups were treated with 100 ng/ml LPS.

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Objective: To explore the inhibitory effects on the activation of endotoxin-induced Kupffer cells (KCs) through short hairpin RNA (shRNA) targeting interleukin-1 receptor associated kinase-4 (IRAK-4) gene.

Methods: Two effective transfection shRNA plasmid (pSIIRAK-4-A, pSIIRAK-4-B) and one invalidated plasmids (pSIIRAK-4-C) targeting IRAK-4 gene were constructed. The isolated mouse KCs were divided into three groups: the normal control group, the RNAi control group (pSIIRAK-4-C) and the RNAi effective group (pSIIRAK-4-A, pSIIRAK-4-B).

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Aim: To observe the 1, 25-dihydroxy vitamin D3 (Vit D3) induced CD14 expression in human U937 cell line and the reaction of the cells to LPS stimulation following the induction.

Methods: U937 cells were cocultured with 0.1 mumol/L Vit D3 for 24 hours to induce the expression of CD14 gene and the sensitiveness of U937 cells to stimulation of LPS at various concentrations and for different times were observed.

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Ethanol inhibits insulin and insulin-like growth factor-I (IGF-I) signaling in a variety of cell types leading to reduced mitogenesis and impaired survival. This effect is associated with inhibition of insulin receptor (IR) and insulin-like growth factor-I receptor (IGF-IR) autophosphorylation, which implicates these receptors as direct targets for ethanol. It was demonstrated previously that ethanol inhibits the autophosphorylation and kinase activity of the purified cytoplasmic tyrosine kinase domain of the IR.

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The cumulative double bond (C[double bond]C[double bond]N), an important intermediate in synthetic organic chemistry, was successfully prepared via the selective attachment of acrylonitrile to Si(111)-7 x 7. The covalent binding of acrylonitrile on Si(111)-7 x 7 was studied using high-resolution electron energy loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning tunneling microscopy (STM) and DFT calculations. The observation of the characteristic vibrational modes and electronic structures of the C[double bond]C[double bond]N group in the surface species demonstrates the [4 + 2]-like cycloaddition occurring between the terminal C and N atoms of acrylonitrile and the neighboring adatom-rest atom pair, consistent with the prediction of DFT calculations.

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