Biomedical subjects

Xia Wu

Publications and source records attributed to Xia Wu.

At least 37 records · Page 2Linked to original sources

PubMed2005

A sensitive fluorimetric method for the determination of epinephrine.

A sensitive fluorimetric method for the determination of epinephrine (E) is described in this paper. The experiments indicate that epinephrine can react with formaldehyde (HCHO) in an acid medium to form a condensation product, which can be oxidized by potassium hexacyanoferrate(III) (K3[Fe(CN)6]) in borax buffer (pH = 9.5). The reaction product can emit strong fluorescence. Ascorbic acid (AA) is used in order to consume excess potassium hexacyanoferrate and stabilize the fluorescent product. Under optimum conditions, a linear relationship has been obtained between the fluorescence intensity and the concentration of epinephrine in the range of 1.4 x 10(-9) - 2.1 x 10(-6) mol/l, and the detection limit is 2.4 x 10(-10) mol/l (4.3 x 10(-11) g/ml, S/N = 3). The method is applied for the determination of E in both actual sample and the synthetic sample with E and norepinephrine (NE) by using the coupling technique of synchronous fluorimetry and H-point standard addition method, and the results obtained are satisfactory.

Ascorbic Acid↗

PubMed2005

The sensitive determination of nucleic acids using fluorescence enhancement of Eu3+-benzoylacetone-cetyltrimethylammonium bromide-nucleic acid system.

A new quantitative method for micro amounts of nucleic acids in aqueous solution is proposed using Eu3+-benzoylacetone (BA) complex as fluorescent probe in the presence of cetyltrimethyl-ammonium bromide (CTMAB). Under the optimum condition, the ratio of the fluorescence intensities with and without nucleic acids is proportional to the concentration of nucleic acid in the range of 1.0x10(-9) to 5.0x10(-6) g/mL for herring sperm DNA (hsDNA), 3.0x10(-9) to 1.0x10(-6) g/mL for calf thymus DNA(ctDNA) and 8.0x10(-9) to 1.0x10(-6) g/mL for yeast RNA (yRNA), and their detection limits are 0.33, 0.21 and 0.99 ng/mL, respectively. Actual sample (DNA of Arabidopsis thaliana) was determined satisfactorily. In addition, the interaction mechanism is also investigated.

Arabidopsis↗

PubMed2005

Gestational-dependent changes in the expression of signal transduction and contractile filament-associated proteins in mouse myometrium.

OBJECTIVES: The timely onset of powerful uterine contractions during parturition involves the integration of many signaling pathways, the protein components of which may be translationaly regulated throughout gestation. We have utilized the pregnant mouse model to examine gestational-dependent changes in the expression of several proteins implicated in the coordination of myometrial excitation-contraction coupling: caveolins 1-3, rho-associated kinases (ROKalpha and beta), alpha-actin, MLC(20), and h-caldesmon. METHODS: Protein expression was examined by Western blotting of myometrial homogenates from nonpregnant mice (NP) and compared to that from pregnant mice on gestational days 12, 15, 17, and 19 (term = day 19). RESULTS: All protein expressions were unchanged during the estrous cycle. alpha-Actin was found to be invariant throughout pregnancy. The expressions of caveolin-1, -2 and -3, when compared to alpha-actin expression, also did not change significantly with mid- to late pregnancy. h-caldesmon: alpha-actin, ROKalpha:alpha-actin, and ROKbeta:alpha-actin ratios were, however, significantly elevated on day 19, whereas MLC(20):alpha-actin was significantly down-regulated on day 12 to day 19. Consistent with elevated ROK expression at term, the ROK inhibitor Y27632 gave a greater reduction of thromboxane-stimulated contractions in myometrium from day 19 mice compared to NP mice. CONCLUSIONS: These data suggest that in mouse myometrium there is a dynamic regulation of the expression of several proteins implicated in contractile signal integration. This may be important for regulating (1) relative uterine quiescence to ensure pregnancy progression and (2) priming the tissue for requisite contractile effort at term.

Animals↗

PubMed2005

Resonance light scattering technique for the determination of protein with rutin and cetylpyridine bromide system.

A new resonance light scattering (RLS) assay of protein is presented. In Tris-NaOH (pH = 10.93) buffer, the RLS of rutin-cetylpyridine bromide (CPB) system can be greatly enhanced by protein, including bovine serum albumin (BSA) and human serum albumin (HSA). The enhanced RLS intensities are in proportion to the concentration of proteins in the range of 5 x 10(-9) to 2.5 x 10(-6) g ml(-1) for BSA and 2.5 x 10(-8) to 3.5 x 10(-6) g ml(-1) for HSA. The detection limits (S/N = 3) are 3.0 ng ml(-1) for BSA and 10.0 ng ml(-1) for HSA. Samples are determined satisfactorily.

Animals↗

PubMed2005

[Primary study of recombinant immunotoxin IL-18-PE38 in treating rheumatoid arthritis].

OBJECTIVE: To establish a kind of gene therapy method of rheumatoid arthritis, to construct the interleukin-18-PE38 fusion gene expression vector and to explore the expression of the fusion gene in the chondrocytes and 3T3 cells. METHODS: Interleukin-18-PE38 fusion gene was cleaved from plasmid PRKL459k-IL-18-PE38 by restriction enzyme digestion, then linked with vectors PsecTag2B and transformed into competence bacteria, positive clones were selected and confirmed by restrictive enzyme (EcoRI) digestion assay. The rearrangement plasmid PsecTag2B-IL-18-PE38 was transfected into 3T3 cells and mouse chondrocytes by liposome protocol (experimental group), null vector was used as negative control, and the transient expression was identified by fluorescence Restrictive enzymes digestion analysis revealed that the length of the interleukin-immunocytochemical assay. RESULTS: 18-PE38 fusion gene was 6000 bp. Fluorescence immunocytochemical method showed that fluorescence intensity of the experimental group is strong,while fluorescence intensity of the control group is weak. CONCLUSION: The eukaryotic expression vector PsecTag2B-IL-18-PE38 is established successfully which can be expressed in the 3T3 cells and mouse chondrocytes. Our results lay a foundation for the further investigation for rheumatoid arthritis therapy.

3T3 Cells↗

PubMed2005

[Construction of interleukin-18-PE38 fusion gene eukaryotic expression vector and its expression in the. chondrocyte].

OBJECTIVE: To construct the interleukin-18-PE38 fusion gene expression vector and explore the expression of the fusion gene in the chondrocyte. METHODS: The recombinant eukaryotic expression vector PsecTag2B-IL-18-PE38 was constructed by inserting interleukin-18-PE38 fusion gene into eukaryotic expression vector PsecTag2B with molecular cloning technique. It was confirmed by restrictive enzymes (EcoR I) digestion assay and PCR. The vector was transfected into primary chrondrocyte by liposome protocol, and the transient expression was identified by fluorescence immunocytochemical assay. RESULTS: Restrictive enzymes digestion analysis and PCR revealed that the interleukin-18-PE38 fusion gene was cloned into the eukaryotic expression vector PsecTag2B successfully. Immunofluorescence photograph of fluorescence immunocytochemical method confirmed that the fusion gene can be expressed in the cytomembrane and cytoplasm. CONCLUSION: The results confirmed that PsecTag2B-IL-18-PE38 fusion gene can be expressed in the chondrocyte, which could serve as a foundation for the study on rheumatoid arthritis therapy.

ADP Ribose Transferases↗

PubMed2004

Study of the interaction of proteins with curcumin and SDS and its analytical application.

It is found that protein and sodium dodecyl sulphonate (SDS) can enhance resonance light scattering (RLS) of curcumin (CU). Based on this phenomenon, a new quantitative method for protein in aqueous solution has been developed. In the BR (pH 3.5) buffer, the RLS intensity of CU-SDS system is greatly enhanced by protein. The enhanced RLS is proportional to the concentration of protein in the range of 0.00020-20.0 microgml(-1) for bovine serum albumin (BSA) and 0.00040-1.0 microgml(-1) for human serum albumin (HSA) and their detection limits are 0.16 and 0.041 ngml(-1), respectively. An actual sample is satisfactorily determined. In addition, the interaction mechanism between protein and CU-SDS is also studied by using multi-techniques such as RLS, absorption spectroscopy and fluorescence, zeta potential assay measurement.

Animals↗

PubMed2004

The fluorescence enhancement effect of the Tb-Gd-guanosine-5'-triphosphate-phen system and its analytical application.

It has been found that Tb(3+) can react with guanosine-5'-triphosphate (GTP) and o-phenanthroline (phen), resulting in the intrinsic fluorescence of Tb(3+). This fluorescence can be enhanced by adding La(3+), Gd(3+), Lu(3+), Sc(3+), Y(3+), and so on, among which Gd(3+) produces the greatest enhancement. These are new co-luminescence systems. The experiments indicate under optimum conditions, the fluorescence intensity of the Tb-Gd-GTP-phen system is proportional to the concentration of GTP over the range 1x10(-9) to 3x10(-5) mol/l. The detection limit is 3.1x10(-10) mol/l. The proposed method provides the most sensitive fluorimetry of GTP so far. The mechanism of the Tb-Gd-GTP-phen system has also been studied. The data indicates that there is a large congeries of Tb-Gd-GTP-phen, and the fluorescence enhancement of the Tb-Gd-GTP-phen system is considered to originate from intramolecular and intermocular energy transfers, and the energy-insulating sheath of the Gd complex.

Gadolinium↗

PubMed2004

[The expression of chemokine receptors in CD56(bright) CD16- natural killer cells and the mechanism of their recruitment in decidua].

OBJECTIVE: To investigate the transcriptions of 18 chemokine receptors in human decidual natural killer (NK) cells and explore the possible mechanisms of preferential accumulation of CD56(bright)CD16(-)NK cells in decidua during first-trimester pregnancy. METHODS: Villi and decidual tissue were collected from normal pregnant women with 5 approximately 10 gestational weeks by artificial abortion. The decidual CD56(bright)CD16(-)NK cells were isolated by immune magnetic beads. The transcription levels of 18 chemokine receptors in the decidual CD56(bright)CD16(-)NK cells were assessed by reverse transcription-polymerase chain reaction (RT-PCR). After the high expression of CXCR4 and CXCR3 mRNA in these cells was found, the expression of stromal cell-derived factor-1 (SDF-1), the specific ligand of CXCR4, in first-trimester human placenta was detected by in situ hybridization and immunohistochemistry. The concentration of SDF-1alpha in the supernatant of culture of isolated trophoblast cells derived from the first-trimester human placentas was measured by ELISA. The chemotaxis of SDF-1 to decidual CD56(bright)CD16(-)NK cells was tested in Transwell, and the chemotactic activity was quantitatively examined. RESULTS: Among the 18 chemokine receptors, CXCR4 and CXCR3 were found highly transcribed in decidual CD56(bright)CD16(-)NK cells. The concentration of SDF-1alpha in the supernatant was 385 ng/L +/- 91 ng/L after trophoblast cells had been cultured for 60 hours. Both rhSDF-1alpha and supernatants in the culture of trophoblast cells exhibited chemotactic activity on decidual CD56(bright)CD16(-)NK cells. When the concentration of rhSDF-1alpha was 10 micro g/L the number of cells that entered the lower chamber of Transwell accounted for 22.9% +/- 4.3% of the total calls. CONCLUSION: First-trimester human trophoblast cells produce SDF-1, which in turn endows the trophoblast cells with the capacity to attract decidual CD56(bright)CD16(-)NK cells highly expressing CXCR4. This activity contributes to the recruitment of decidual lymphocytes and may be used at a local level to manipulate the microimmune environment at the materno-fetal interface.

CD56 Antigen↗

PubMed2004

Advances in the study of luminescence probes for proteins.

Spectral probes (or labels) have been widely used for the investigation and determination of proteins and have made considerable progress. Traditional luminescence probes include fluorescent derivatizing reagents, fluorescent probes and chemiluminescence probes which continue to develop. Of them, near infrared (NIR) fluorescent probes are especially suitable for the determination of biomolecules including proteins, so their development has been rapid. Novel luminescence probes (such as nanoparticle probes and molecular beacons) and resonance light scattering probes recently appeared in the literature. Preliminary results indicate that they possess great potential for ultrasensitive protein detection. This review summarizes recent developments of the above-mentioned probes for proteins and 195 references are cited.

Luminescent Measurements↗

PubMed2004

Study on the interaction between nucleic acids and cationic surfactants.

The interactions of nucleic acids and cationic surfactants (cetylpyridine bromide (CPB) and cetyltrimethylammonium bromide (CTMAB)) in aqueous solution have been studied using the techniques of resonance light scattering (RLS) spectroscopy, the absorption spectroscopy, zeta potential assay and NMR assignment measurement. It is considered that CPB or CTMAB can assemble on the surface of nucleic acid via electrostatic and hydrophobic forces, which results in the formation of large associate of nucleic acid-cationic surfactant and RLS enhancement of nucleic acid. Besides these forces, the pi-pi stacking force between CPB and nucleic acid also exists in the associate. In comparison with CTMAB, CPB has larger enhancement on RLS of nucleic acid, which is attributed to that the enhancement of the former is only due to the absorption of the bases of nucleic acid, while the enhancement of the latter is own to the synergetic resonance caused by the absorption of both bases of nucleic acid and the pyridyl in CPB. These results have important implication for understanding the influence of surfactants on nucleic acid functionality in life science.

Bromides↗

PubMed2004

The expression of CXCR4/CXCL12 in first-trimester human trophoblast cells.

Chemokines and chemokine receptors have been implicated as pivotal players in many physiological and pathological situations, but little is known about the expression and function of chemokines and chemokine receptors at the materno-fetal interface. In this study, we first analyzed the transcription of 18 chemokine receptors in first-trimester human trophoblast cells. Among these receptors, CXCR4 was found highly transcribed. We demonstrated afterward that both CXCR4 and CXCL12 (stromal cell-derived factor-1; SDF-1) were expressed in trophoblast cells. Primary cultured trophoblast cells were also found secreting CXCL12 spontaneously. To identify the functional role of CXCR4/CXCL12 in these cells, we treated trophoblast cells with recombinant human (rh)SDF-1 alpha and analyzed the cell viability and signaling pathway. The results showed that rhSDF-1 alpha increased the viability of trophoblast cells and the activation of extracellular signal-regulated kinases signaling pathway in vitro. Our findings suggest that first-trimester trophoblast cells express functional CXCR4/CXCL12, which may play an important role in early pregnancy such as stimulating trophoblast cell proliferation or differentiation in an autocrine manner.

Base Sequence↗

PubMed2004

Study on the fluorescent enhancement effect in terbium-gadolinium-protein-sodium dodecyl benzene sulfonate system and its application on sensitive detection of protein at nanogram level.

The co-luminescence effect in a terbium-gadolinium-protein-sodium dodecyl benzene sulfonate (SDBS) system is reported here. Based on it, the sensitive quantitative analysis of protein at nanogram levels is established. The co-luminescence mechanism is studied using fluorescence, resonance light scattering (RLS), absorption spectroscopy and NMR measurement. It is considered that protein could be unfolded by SDBS, then a efficacious intramolecular fluorescent energy transfer occurs from unfolded protein to rare earth ions through SDBS acting as a "transfer bridge" to enhance the emission fluorescence of Tb3+ in this ternary complex of Tb-SDBS-BSA, where energy transfer from protein to SDBS by aromatic ring stacking is the most important step. Cooperating with the intramolecular energy transfer above is the intermolecular energy transfer between the simultaneous existing complexes of both Tb3+ and Gd3+. The fluorescence quantum yield is increased by an energy-insulating sheath, which is considered to be another reason for the resulting enhancement of the fluorescence. Förster theory is used to calculate the distribution of enhancing factors and has led to a greater understanding of the mechanisms of energy transfer.

Absorption↗

PubMed2004

Histamine production via mast cell-independent induction of histidine decarboxylase in response to lipopolysaccharide and interleukin-1.

Histamine modulates immune responses. There are at least two ways histamine might be supplied: one is its release from cells that pool pre-formed histamine and the other is its de novo formation via induction of histidine decarboxylase (HDC). Lipopolysaccharide (LPS) and the proinflammatory cytokine interleukin (IL)-1 induce a marked elevation of HDC activity in various tissues or organs. To examine the contribution of mast cells to HDC induction in mice given LPS or IL-1, we examined the effects of LPS and IL-1 on HDC activity and/or histamine content in various organs (liver, lung, spleen or bone marrow) in mast cell-deficient mice (W/Wv), their normal littermates (+/+) and BALB/c mice deficient in IL-1alpha, IL-1beta and tumor necrosis factor (TNF)-alpha (IL-1alpha beta/TNFalphaKO mice). In non-stimulated mice, the histamine in the lung and spleen was contained largely within mast cells. The LPS-stimulated increase in HDC activity in a given organ was similar between +/+ and W/W(v) mice, and between IL-1alpha beta/TNFalphaKO BALB/c and control BALB/c mice, and led to increases in histamine. In W/Wv and +/+ mice, IL-1alpha also elevated HDC activity. These results suggest that (i) in liver, lung and spleen, either the major cells supplying histamine via HDC induction in response to LPS and IL-1 are not mast cells, or mast cells are not a prerequisite for the induction of HDC; (ii) the cells in which HDC is induced by LPS and IL-1 are similar or identical in a given organ; and (iii) neither IL-1 nor TNF-alpha is a prerequisite for the induction of HDC by LPS.

Animals↗

PubMed2004

Determination of dysprosium by resonance light scattering technique in the presence of BPMPHD.

Dysprosium has been determined by resonance light scattering (RLS) method in the presence of 1,6-bi(1'-phenyl-3'-methyl-5'-pyrazolone-4'-)hexanedione (BPMPHD) at pH 5.5. The Dy-BPMPHD system has three characteristic peaks at 358, 399 and 450 nm, especially the peak at 358 nm, which is proportional to the concentration of Dy(3+) in the range of 1.0 x 10(-10)-1.0 x 10(-5) mol l(-1). The detection limit (S/N=2) is 5.6 x 10(-12) mol l(-1). Synthetic samples are determined satisfactorily. A new sensitive method for detection of dysprosium has been proposed.

Animals↗

PubMed2004

Study of the reaction between the nucleic acid and Y-BPMPHD-CTMAB complex and its analytical application.

The fluorescence quenching of the Y-BPMPHD-CTMAB by nucleic acids is reported. It is considered that the Y-BPMPHD-CTMAB can form a large complex with nucleic acid through the electrostatic attraction in the pH range of 4.2-6.8. Under optimal conditions, the difference of fluorescence intensity between the system without and with nucleic acids is proportional to the concentration of nucleic acids over the range of 4.5 x 10(-8)-1.2 x 10(-5) g/mL for fsDNA and 3.2 x 10(-8)-3.0 x 10(-5) g/mL for yRNA, respectively. The detection limits are 14.0 ng/mL for fsDNA and 21.0 ng/mL for yRNA. The method is applied for the determination of nucleic acids in actual sample, and the result obtained is satisfactory.

Buffers↗

PubMed2004

Sensitive determination of carbohydrates by fluorimetric method with Ce(IV) and sodium triphosphate.

A new simple and sensitive fluorimetric method for the determination of carbohydrates is described. The method is based on the reaction between carbohydrates and Ce(IV) in the presence of sulfuric acid. All the reductive carbohydrates can be detected indirectly by the fluorescence of Ce(III) produced. The addition of sodium triphate enhances the sensitivity of the method by more than 10-folds. Under optimum conditions, an excellent linear relationship was obtained between the fluorescence intensity and the concentration of carbohydrates. The limits of detection lie in the range of 9.3 x 10(-10) - 1.3 x 10(-9) mol/L. As compared to the normal fluorimetric method, the proposed method is faster and more sensitive.

Carbohydrates↗

PubMed2004

New lanostane-type triterpenes from Fomes officinalis.

Five new lanostane-type triterpenes, named fomefficinic acid A-E (1-5), were isolated from the dried sclerotium of Fomes officinalis, respectively. Their structures were established as 24-methylene-3-oxo-lanost-8-en-21-oic acid (1), 3alpha,15alpha-dihydroxy-24-methylene-lanosta-7,9(11)-dien-21-oic acid (2), 3alpha,15alpha-dihydroxy-24-methylene-lanost-8-en-21-oic acid (3), 15alpha-hydroxy-3-oxo-24-methylenelanost-8-en-21-oic acid (4), 15alpha-acetoxy-3-oxo-24-methylenelanosta-7,9(11)-dien-21-oic acid (5), by spectral analysis and chemical methods as well as comparison with known compounds.

Lanosterol↗