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Xin Lu

Publications and source records attributed to Xin Lu.

At least 73 records · Page 4Linked to original sources
PubMed2005

Posttranslational modifications of p27kip1 determine its binding specificity to different cyclins and cyclin-dependent kinases in vivo.

Using 2-dimensional gel electrophoresis (2D-gel) analysis, we show here that cell-cycle entry is associated with a significant increase in p27(kip1) phosphorylation in human primary B cells. A similar pattern of increase in p27(kip1) phosphorylation was also seen in 2 fast-growing tumor cell lines, Burkitt lymphoma cell line BL40 and breast carcinoma cell line Cal51, where inactive p27(kip1) is expressed at high levels. Detailed analysis revealed for the first time that different cyclins and cyclin-dependent kinases (cdk's) interact with distinct posttranslationally modified isoforms of p27(kip1) in vivo. Cyclin E but not cyclin A selectively interacts with phosphorylated p27(kip1) isoforms, while cyclin D1 and D2 favor unphosphorylated p27(kip1) isoforms in vivo. Interestingly, cyclin D3 and cdk4 selectively interact with phosphorylated p27(kip1) in BL40 cells. Among all D-type cyclin/cdk4 and cdk6 complexes, cyclin D3/cdk4 is most active in sequestering the inhibitory activity of p27(kip1) in vitro in a cyclinE/cdk2 kinase assay. This novel feature of the binding specificity of p27(kip1) to cyclins and cdk's in vivo is interpreted in the context of overexpression of cyclin D3 in the presence of high levels of p27(kip1) in human B-cell lymphomas with adverse clinical outcome.

B-Lymphocytes↗
PubMed2005

A facile and sensitive chemiluminescence detection of amino acids in biological samples after capillary electrophoretic separation.

It was found that native amino acids enhanced the chemiluminescence (CL) reaction between luminol and BrO(-) in an alkaline aqueous solution. This has led to the development of a facile and highly sensitive CL detection scheme for the determination of amino acids in biological samples after capillary electrophoretic (CE) separation. The CE-CL conditions were optimized. An electrophoretic buffer of 2.5 x 10(-2) M sodium borate (pH 9.4) containing 1 x 10(-4) M luminol was used. The oxidizer solution of 8 x 10(-4) M NaBrO in 0.1 M sodium carbonate buffer solution (pH 12.5) was introduced post-column. Under the optimal conditions, the detection limits were 1.0 x 10(-7) M for glutamic acid (Glu) and 1.3 x 10(-7) M (S/N = 3) for aspartic acid (Asp). The relative standard deviations (RSDs) of peak area and migration time were in the ranges of 3.8-4.3% and 1.4-1.6%, respectively. The present method was applied to the determination of excitatory amino acids (i.e., Asp and Glu) in rat brain tissue and monkey plasma. The levels of these major excitatory amino acids in monkey plasma were quantified for the first time and found to be 1.17 +/- 0.17 x 10(-5) M (mean +/- SD, n = 6) for Glu and 1.64 +/- 0.19 x 10(-6) M for Asp, which were comparable with the levels in human plasma.

Animals↗
PubMed2005

Identification of phospholipid structures in human blood by direct-injection quadrupole-linear ion-trap mass spectrometry.

Direct-injection electrospray ionization mass spectrometry in combination with information-dependent data acquisition (IDA), using a triple-quadrupole/linear ion trap combination, allows high-throughput qualitative analysis of complex phospholipid species from child whole blood. In the IDA experiments, scans to detect specific head groups (precursor ion or neutral loss scans) were used as survey scans to detect phospholipid classes. An enhanced resolution scan was then used to confirm the mass assignments, and the enhanced product ion scan was implemented as a dependent scan to determine the composition of each phospholipid class. These survey and dependent scans were performed sequentially and repeated for the entire duration of analysis, thus providing the maximum information from a single injection. In this way, 50 different phospholipids belonging to the phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, phosphatidylcholine and sphingomyelin classes were identified in child whole blood.

Child↗
PubMed2005

Effect of siRNA targeting survivin gene on the biological behavior of hepatocellular carcinoma.

To study the influence of siRNA targeting survivin gene on the biological behavior of hepatocellular carcinoma (HCC), one pair of 21bp reverse repeated. motifs of survivin target sequence with 9 spacers were synthesized and inserted into plasmid psilencer2. 1 to generate siRNA eukaryotic expression vector. After stable transfection into HepG2 cells, the biological behaviors of the survivin siRNA transfected HCC cells were observed. After the recombinant plasmid Psilence (+)-survivin was successfully constructed, survivin mRNA and protein expression inhibition ratio reached 73 % and 75% respectively compared to control groups. Transfected cells with survivin siRNA demonstrated significantly inhibited cell growth and increased apoptosis. Subsequent study in nude mouse model demonstrated lower succeeding rate in cells transfected with survivin siRNA and slow growth rate. The results elucidated the siRNA targeting survivin gene could specially suppress its expression in HepG2 cells and inhibit tumor cells growth both in vivo and in vitro. This provides a theoretical basis to turn the drug resistance in tumor cells.

Apoptosis↗
PubMed2005

Proteomic profiling in the sera of workers occupationally exposed to arsenic and lead: identification of potential biomarkers.

Arsenic (As) and lead (Pb) are important inorganic toxicants in the environment. Frequently, humans are exposed to the mixtures of As and Pb, but little is known about the expression of biomarkers resulting from such mixed exposures. In this study, we analyzed serum proteomic profiles in a group of smelter workers with the aim of identifying protein biomarkers of mixed As and Pb exposure. Forty-six male workers co-exposed to As and Pb were studied. Forty-five age-matched male office workers were chosen as controls. Urine As and blood Pb concentrations were determined. Serum proteomic profiles were analyzed by Surface-Enhanced Laser Desorption/Ionization Time-Of-Flight (SELDI-TOF) mass spectrometer on the WCX2 ProteinChip. Using Recursive support vector machine (RSVM) algorithm, a panel of five peptides/proteins (2097 Da, 2953 Da, 3941 Da, 5338 Da, and 5639 Da) was selected based on their collective contribution to the optional separation between higher metal mixture exposure and non-exposure controls. Among these five selected markers, the 3941 Da was down-regulated and the four other proteins were up-regulated. Descriptive statistics confirmed that these five proteins differed significantly between metal exposure and non-exposure. Interestingly, the combined use of the five selected biomarkers could achieve higher discriminative power than single marker. These results demonstrated that proteomic technology, in conjunction with bioinformatics tools, could facilitate the discovery of new and better biomarkers of mixed metal exposure.

Adult↗
PubMed2005

p53: a heavily dictated dictator of life and death.

In 2003, a p53-expressing adenovirus was approved as a cancer therapy drug in China. Consequently, there has been a surge in the need to understand the regulation of wild type p53 function in vivo. The majority of the progress made during the past two years has focused on the cellular factors and post-translational modifications that regulate the expression levels and activities of p53 in response to stress signals.

Animals↗
PubMed2005

Effect of praseodymium(III) on zinc(II) species in human interstitial fluid.

A multiphase model of metal ion species in human interstitial fluid was constructed under physiological conditions. The effect of Pr(III) on Zn(II) species was studied. At the normal conditions, Zn(II) species mainly distribute in [Zn(HSA)], [Zn(IgG)], and [Zn(Cys)(2)H](+). With the Pr(III) level increased, the apparent competition of Pr(III) for ligands lead to the redistribution of Zn(II) species.

Binding, Competitive↗
PubMed2005

[Mechanisms of increased survival rate by administration of AG490 in rats following extensive liver resection].

OBJECTIVE: To study the mechanism by which AG490 improves the survival rate of rats following extensive liver resection. METHODS: Thirty-eight rats were randomly divided into two groups after surgery: control group (n=10), without treatment; (2) AG490 group (n=28), with AG490 (1 mg x kg(-1) x 12 h(-1)) administrated intraperitoneally immediately and 36 hours after the operation. The survival rate was observed and the serum liver functions were measured. RESULTS: The survival rates of control group and AG490 group were 0% and 25%. AG490 group had significantly better blood glucose and aminotransferase levels (P < 0.05) than control group; serum bilirubin levels significantly decreased 48 hours after the operation. Serum protein levels in both two groups had slow decrease but without statistical significance (P > 0.05). CONCLUSIONS: AG490 can significantly increase the survival rate of rats following extensive liver resection. Such a benefit mainly results from the protection towards residual liver function rather than from the promotion of liver regeneration.

Alanine Transaminase↗
PubMed2005

[Multidimensional separations used in pharmaceutical and biological fields].

A review of multidimensional separations such as comprehensive two-dimensional gas chromatography (GC x GC), comprehensive two-dimensional high performance liquid chromatography (HPLC x HPLC) and their applications in pharmaceutical and biological fields is presented with 71 references. A single CO2 cryo-jet loop modulator was developed for GC x GC and it can be used to modulate compounds higher than C6 effectively. Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC/TOF-MS) analyses of traditional Chinese medicine volatile oils such as Pogostemon cablin Benth (Cablin Patchouli), Forsythia suspensa (Thunb.) Vahl and Zedoary were reported also. As an emerging technology, multidimensional separations hold the promise and play an important role in the future pharmaceutical and biological fields.

Animals↗
PubMed2005

[Dead time determination of the second dimension in a comprehensive two-dimensional gas chromatography].

Comprehensive two-dimensional gas chromatography (GC x GC) is rapidly gaining importance for the analysis of complex samples. In order to predict chromatogram and optimize the operational conditions, the dead time of each dimension should be obtained exactly. Two methods to calculate the dead time of the second dimension were introduced. In the first method, based on the relationship between the time differences of a series of n-alkanes substances and the apparent retention times under different pressures, the true retention time can be calculated for non-synchronous GC x GC. The retention times of homologous series were used to calculate the dead time. Another rapid method to calculate the dead time of the second dimension is based on three or more apparent retention times in a single temperature programmed chromatographic run. The results show that the dead time of the second dimension can be calculated successfully by using the proposed methods and the deviation between the two methods is less than 0.05 s.

Algorithms↗
PubMed2005

[Nitrate vertical transport and simulating model in saturated soils in typical region].

By simulating soil column in laboratory, the nitrate vertical transport characteristics in farmland soil in Fengqu region of Henan Province were studied. The results show that, under saturated soil condition, the different concentrations of nitrate (100 mg x L(-1) 200mg x L(-1)) had no obvious influence on the breakthrough curves (BTCs) of nitrate vertical transport. When the soil columns were eluted by nitrate solution containing co-existing cations (K+ and Ca2+), the BTCs of nitrate vertical transport in the topsoil(0 - 30cm) of yellow fluvo-aquic soil and aeolian sandy soil were very similar. However, the outflow time of nitrate in the middle and bottom soil layers in the yellow fluvo-aquic soil was significantly extended, when the soil columns were eluted by nitrate solution containing Ca2+. The longer the outflow time of nitrate transport out of soil column was, the evener and lower the peak of the BTCs was. The mathematical model, CXTFIT2.0, could be applied to accurately estimate nitrate leaching mass in the saturated soil with steady-state flow condition. The fitted BTCs were in good agreement with the observed BTCs, which had high correlative coefficients (0.8594 - 0.9978).

Models, Theoretical↗
PubMed2005

[Applications and progresses of expert system on chromatography].

The expert system on chromatography has achieved great advancement in the past two decades, and is playing a more and more important role in solving analytical problems of complex samples. Research results of expert system on chromatography in authors' group are reviewed with 64 references. A brief introduction of the expert system on chromatography is presented. Applications of the expert system on chromatography are summarized in the fields of petrochemical online analysis, environmental air sample analysis, tumor diagnosis and traditional Chinese medicine analysis. The review followed the scientific foot steps in the authors' group, starting from the development of the expert system on gas chromatography, to the selection of multi-column systems in online industrial gas chromatographs in petrochemical plants, and to the employment of the new techniques in gas chromatography, liquid chromatography and capillary electrophoresis to solve the practical analytical problems in the nation's scientific and economic development.

Chromatography↗
PubMed2005

[A new culture method for primordial germ cell].

To investigate the new method that the primordial germ cells (PGCs) can long time propagate, grow and keep potency of differentiation in vitro. PGCs were co-cultured with Sertoli cells (SCs) or with homologue fibroblasts from genital ridge. When co-cultured with SCs, PGCs colonies and times of transfer of culture were greater than those co-cultured with homologue fibroblasts. At present PGCs of co-cultured with SCs have succeeded in subculturing to the 51 generation. SCs can availably enhance propagating ability as well as a long period of time maintain the characteristic of PGCs.

Animals↗
PubMed2005

[Hysteretic characteristics of atrazine desorption from fluvo-aquic soil].

Kinetic batch experiments are carried out in order to investigate the effects of a wide range of atrazine initial concentrations and consecutive desorption time on the desorption characteristics of atrazine from fluvo-aquic soil. The results reveal that, atrazine concentrations in soil solution gradually decreased with desorption time increasing, whose relationship can be expressed with empirically exponential functions. After consecutive five steps (or 5 days), when atrazine initial concentrations increased from 50 microg x L(-1) to 2000 microg x L(-1), the average desorption percentages were 23.1%, 30.4%, 33.0%, 36.4% and 38.5%, respectively. The relationships between the amount of atrazine adsorbed by soil colloids and corresponding atrazine concentrations in soil solutions may be described through the traditional and time-dependent desorption isotherms. The obvious discrepancies in two families of both traditional and time-dependent desorption isotherms from adsorption isotherm, which retention time last for 168 hours before commencement of desorption, were indicative of hysteresis. Two sets of Freundlich parameters derived from both desorption isotherms can quantify the hysteresis between desorption and adsorption isotherms. However, hysteresis coefficient, omega, was applicable only for the traditional desorption isotherms, H and lamda applicable for both.

Adsorption↗
PubMed2004

Filamin A binding stabilizes nascent glycoprotein Ibalpha trafficking and thereby enhances its surface expression.

The glycoprotein (Gp) Ib-IX-V complex is essential for platelet-mediated hemostasis and thrombosis. The cytoplasmic domain of its largest polypeptide subunit GpIbalpha possesses a binding region for filamin A, which links GpIb-IX-V to the platelet cytoskeleton. There is evidence that filamin A binding to GpIbalpha directs the surface expression of GpIb-IX. To investigate the mechanism of this effect, we examined GpIbalpha biosynthesis in Chinese hamster ovary (CHO) cells stably co-expressing wild-type or mutant GpIbalpha with GpIbbeta, GpIX with and without filamin A. We observed that surface GpIbalpha expression is enhanced in CHO cells co-expressing human filamin A. In comparison with cells expressing only GpIbalpha, GpIbbeta, and GpIX (CHO-GpIbalpha/betaIX), lysates from CHO-GpIbalpha/betaIX + filamin A-expressing cells showed greater amounts of immature, incompletely O-glycosylated and fully mature GpIbalpha, but lesser amounts of the approximately 15-kDa C-terminal peptide released when the extracellular domain of GpIbalpha is cleaved by proteases. When filamin A binding is eliminated by truncation of GpIbalpha at C-terminal residue 557 or by a deletion between amino acids 560-570, the decreased synthesis of mature GpIbalpha is accompanied by decreased immature GpIbalpha and by an increased immunodetectable C-terminal peptide. The synthesis of mature GpIbalpha in CHO-GpIbalpha/betaIX cells is eliminated by brefeldin A (which inhibits transport out of the endoplasmic reticulum (ER)) and restored by lactacystin (which inhibits proteasomal degradation). These results suggest that GpIbalpha binds to filamin A within the ER and that filamin A binding directs post-ER trafficking of GpIbalpha to the cell surface.

Acetylcysteine↗
PubMed2004

Xin Lu.

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China↗