Biomedical subjects

Yan Du

Publications and source records attributed to Yan Du.

At least 19 recordsLinked to original sources

PubMed2026

RHAMM drives formation of polyploid cancer cells and confers resistance to ER-targeted therapy in breast cancer.

Endocrine resistance in ER+ breast cancer remains a major clinical challenge. Here, we identify RHAMM as a key driver of resistance by orchestrating polyploid cancer cell (PCC) formation. Single-cell transcriptomics uncovered a G2/M-enriched, RHAMM+ subpopulation in endocrine-resistant tumors. Mechanistically, RHAMM binds Septin9/10 to promote aberrant cytoskeleton polymerization, activating YAP independent of Hippo signaling, which induces cytokinesis failure and facilitates PCC generation. Concurrently, RHAMM destabilizes p21 mRNA, enabling cell cycle progression despite genomic instability. The RHAMM-p21 axis serves as a bypass mechanism supporting polyploidization. Upon endocrine treatment, RHAMM is transcriptionally up-regulated by Slug. Clinically, RHAMMhigh signatures are enriched in metastatic and recurrent ER+ tumors and correlate with poor prognosis, highlighting its therapeutic relevance. Importantly, targeting RHAMM or YAP abrogates PCC formation and restores fulvestrant sensitivity. These findings reveal RHAMM-mediated polyploidization as an adaptive mechanism underlying endocrine resistance, suggesting the therapeutic potential of targeting the RHAMM-YAP axis.

Humans↗

PubMed2006

Synthesis of PtNPs/AQ/Ru(bpy)3(2+) colloid and its application as a sensitive solid-state electrochemiluminescence sensor material.

The facile synthesis of the novel platinum nanoparticles/Eastman AQ55D/ruthenium(II) tris(bipyridine) (PtNPs/AQ/Ru(bpy)3(2+)) colloidal material for ultrasensitive ECL solid-state sensors was reported for the first time. The cation ion-exchanger AQ was used not only to immobilize ECL active species Ru(bpy)3(2+) but also as the dispersant of PtNPs. Colloidal characterization was accomplished by transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), and UV-vis spectroscopy. Directly coating the as-prepared colloid on the surface of a glassy carbon electrode produces an electrochemiluminescence (ECL) sensor. The electronic conductivity and electroactivity of PtNPs in composite film made the sensor exhibit faster electron transfer, higher ECL intensity of Ru(bpy)3(2+), and a shorter equilibration time than Ru(bpy)3(2+) immobilized in pure AQ film. Furthermore, it was demonstrated that the combination of PtNPs and permselective cation exchanger made the sensor exhibite excellent ECL behavior and stability and a very low limit of detection (1 x 10(-15) M) of tripropylamine with application prospects in bioanalysis. This method was very simple, effective, and low cost.

Journal Article↗

PubMed2006

Pt nanoparticles: Heat treatment-based preparation and Ru(bpy)(3)2+-mediated formation of aggregates that can form stable films on bare solid electrode surfaces for solid-state electrochemiluminescence detection.

A simple thermal process for the preparation of small Pt nanoparticles is presented, carried out by heating a H2PtCl6/3-thiophenemalonic acid aqueous solution. The following treatment of such colloidal Pt solution with Ru(bpy)(3)2+ causes the assembly of Pt nanoparticles into aggregates. Most importantly, directly placing such aggregates on bare solid electrode surfaces can produce very stable films exhibiting excellent electrochemiluminescence behaviors.

Journal Article↗

PubMed2006

Dynamic positive feedback phosphorylation of mixed lineage kinase 3 by JNK reversibly regulates its distribution to Triton-soluble domains.

MLK3 (mixed lineage kinase 3) is a widely expressed, mammalian serine/threonine protein kinase that activates multiple MAPK pathways. Previously our laboratory used in vivo labeling/mass spectrometry to identify phosphorylation sites of activated MLK3. Seven of 11 identified sites correspond to the consensus motif for phosphorylation by proline-directed kinases. Based on these results, we hypothesized that JNK, or another proline-directed kinase, phosphorylates MLK3 as part of a feedback loop. Herein we provide evidence that MLK3 can be phosphorylated by JNK in vitro and in vivo. Blockade of JNK results in dephosphorylation of MLK3. The hypophosphorylated form of MLK3 is inactive and redistributes to a Triton-insoluble fraction. Recovery from JNK inhibition restores MLK3 solubility and activity, indicating that the redistribution process is reversible. This work describes a novel mode of regulation of MLK3, by which JNK-mediated feedback phosphorylation of MLK3 regulates its activation and deactivation states by cycling between Triton-soluble and Triton-insoluble forms.

Cell Line↗

PubMed2006

Field-amplified sample stacking capillary electrophoresis with electrochemiluminescence applied to the determination of illicit drugs on banknotes.

Capillary electrophoresis (CE) with Ru(bpy)3(2+) electrochemiluminescence (ECL) detection system was established to the determination of contamination of banknotes with controlled drugs and a high efficiency on-column field-amplified sample stacking (FASS) technique was also optimized to increase the ECL intensity. The method was illustrated using heroin and cocaine, which are two typical and popular illicit drugs. Highest sample stacking was obtained when 0.01 mM acetic acid was chosen for sample dissolution with electrokinetical injection for 6 s at 17 kV. Under the optimized conditions: ECL detection at 1.2 V, separation voltage 10.0 kV, 20 mM phosphate-acetate (pH 7.2) as running buffer, 5 mM Ru(bpy)3(2+) with 50 mM phosphate-acetate (pH 7.2) in the detection cell, the standard curves were linear in the range of 7.50x10(-8) to 1.00x10(-5) M for heroin and 2.50x10(-7) to 1.00x10(-4) M for cocaine and detection limits of 50 nM for heroin and 60 nM for cocaine were achieved (S/N = 3), respectively. Relative standard derivations of the ECL intensity and the migration time were 3.50 and 0.51% for heroin and 4.44 and 0.12% for cocaine, respectively. The developed method was successfully applied to the determination of heroin and cocaine on illicit drug contaminated banknotes without any damage of the paper currency. A baseline resolution for heroin and cocaine was achieved within 6 min.

Cocaine↗

PubMed2006

Facile separation and determination of Aconitine alkaloids in traditional Chinese medicines by CE with tris(2,2'-bipyridyl) ruthenium(II)-based electrochemiluminescence detection.

A facile CE method coupled with tris(2,2'-bipyridyl) ruthenium(II)-based electrochemiluminescence [Ru(bpy)(3) (2+)] detection was developed for simultaneous determination of Aconitum alkaloids, i.e., hypaconitine (HA), aconitine (AC), and mesaconitine (MA) in baseline separation. The optimal separation of these Aconitum alkaloids was achieved in a fused-silica capillary column (50 cm x 25 microm id) with 30 mM phosphate solution (pH 8.40) as running buffer at 12 kV applied voltage. The three alkaloids can be determined within 10 min by a single run. The calibration curves showed a linear range from 2.0 x 10(-7) to 2.0 x 10(-5) M for HA, 3.4 x 10(-7) to 1.7 x 10(-5) M for AC, and 3.8 x 10(-7) to 1.9 x 10(-5) M for MA. The RSDs for all analytes were below 3.01%. Good linear relationships were found with correlation coefficients for all analytes exceeding 0.993. The detection limits were 2.0 x 10(-8) M for HA, 1.7 x 10(-7) M for AC, and 1.9 x 10(-7) M for MA under optimal conditions. This method was successfully applied to determine the three alkaloids in Aconitum plants.

2,2'-Dipyridyl↗

PubMed2006

[Study on measurement of liquid refractive index by analyzing SPR spectrum character].

The principle of optic fiber surface plasmon resonance sensor is discussed in detail based on the electromagnetic theory and radial theory in the present paper. The relationship between SPR spectrum resonance wavelength and liquid refractive index is also analyzed. Through relative spectrum measurement technology, SPR spectrum curves, whose resonance wavelength increases with increasing liquid refractive index, were obtained for eight different kinds of chemical liquids. The measurement of concentration of mixed solution including ethanol and glycol was performed by analyzing the spectrum attribute. The experimental results show that the sensing system features simple structure and all light transmitted by fiber. It not only realizes rapid, accurate and real time measurement for target medium, but also can be used in some special situations and easily realize long distance measurement.

English Abstract↗

PubMed2005

Microchip capillary electrophoresis with solid-state electrochemiluminescence detector.

We report microchip capillary electrophoresis (CE) coupling to a solid-state electrochemiluminescence (ECL) detector. The solid-state ECL detector was fabricated by immobilizing tris(2,2'-bipyridyl)ruthenium(II) (TBR) into an Eastman AQ55D-silica-carbon nanotube composite thin film on an indium tin oxide (ITO) electrode. After being made by a photolithographic method, the surface of the ITO electrode was coated with a thin composite film through a micromolding in capillary (MIMIC) technique using a poly(dimethylsiloxane) (PDMS) microchannel with the same pattern as an ITO electrode. Then the TBR was immobilized via ion exchange by immersing the ITO electrode containing the thin film in TBR aqueous solution. The whole system was built by reversibly sealing the TBR-modified ITO electrode plate with a PDMS layer containing electrophoresis microchannels. The results indicated that the present solid-state ECL detector displayed good durability and stability in the microchip CE-ECL system. Proline was selected to perform the microchip device with a limit of detection of 2 microM (S/N=3) and a linear range from 25 to 1000 microM. Compared with the CE-ECL of TBR in aqueous solution, while the CE microchip with solid-state ECL detector system gave the same sensitivity of analysis, a much lower TBR consumption and a high integration of the whole system were obtained. The present system was also used for medicine analysis.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2005

Method for effective immobilization of Ru(bpy)(3)2+ on an electrode surface for solid-state electrochemiluminescene detection.

A novel method for effective immobilization of Ru(bpy)3(2+) on an electrode surface is developed. The whole process involves two steps: the electrostatic interactions between citrate-capped gold nanoparticles (AuNPs) and Ru(bpy)3Cl2 in aqueous medium were used to fabricate Ru(bpy)(3)2+-AuNP aggregates (Ru-AuNPs) first, and then the Au-S interactions between as-formed Ru-AuNPs and sulfhydryl groups were used to effectively immobilize the Ru-AuNPs on a sulfhydryl-derivated indium tin oxide (ITO) electrode surface. As-prepared ITO electrode shows excellent stability, and the ECL active species Ru(bpy)3(2+) contained therein exhibit excellent ECL behaviors.

Journal Article↗

PubMed2005

Cdc42 induces activation loop phosphorylation and membrane targeting of mixed lineage kinase 3.

Mixed lineage kinase 3 (MLK3) functions as a mitogen-activated protein kinase kinase kinase to activate multiple mitogen-activated protein kinase pathways. Our current studies demonstrate that lack of MLK3 blocks signaling of activated Cdc42 to c-Jun N-terminal kinase, giving strong support for the idea that Cdc42 is a physiological activator of MLK3. We show herein that Cdc42, in a prenylation-dependent manner, targets MLK3 from a perinuclear region to membranes, including the plasma membrane. Cdc42-induced membrane targeting of MLK3 is independent of MLK3 catalytic activity but depends upon an intact Cdc42/Rac-interactive binding motif, consistent with MLK3 membrane translocation being mediated through direct binding of Cdc42. Phosphorylation of the activation loop of MLK3 requires MLK3 catalytic activity and is induced by Cdc42 in a prenylation-independent manner, arguing that Cdc42 binding is sufficient for activation loop autophosphorylation of MLK3. However, membrane targeting is necessary for full activation of MLK3 and maximal signaling to JNK. We previously reported that MLK3 is autoinhibited through an interaction between its N-terminal SH3 domain and a proline-containing sequence found between the leucine zipper and the CRIB motif of MLK3. Thus we propose a model in which GTP-bound Cdc42/Rac binds MLK3 and disrupts SH3-mediated autoinhibition leading to dimerization and activation loop autophosphorylation. Targeting of this partially active MLK3 to membranes likely results in additional phosphorylation events that fully activate MLK3 and its ability to maximally signal through the JNK pathway.

Amino Acid Motifs↗

PubMed2005

Microfluidic chip with electrochemiluminescence detection using 2-(2-aminoethyl)-1-methylpyrrolidine labeling.

A tertiary amine derivative, 2-(2-aminoethyl)-1-methylpyrrolidine (AEMP) was successfully developed as electrochemiluminescence (ECL) probe within microfluidic chip using ECL detection in this paper. The system was characterized by the interaction between biotin and avidin. In principle, tertiary amine derivatives containing active group can be used as a potential alternative of traditional tris(2,2'-bipyridine)ruthenium(II) [Ru(bpy)3(2+)] label. Firstly, The ECL efficiency of AEMP was characterized via comparing with that of two coreactants enhancing Ru(bpy)3(2+) ECL, TPA and proline. At same condition, AEMP has a similar ECL efficiency to TPA, and much higher than proline. After AEMP reacted with NHS-LC-biotin (succinimidyl-6-(biotinamido) hexanoate), the products and their ECL were analyzed by directly injecting it in the microfluidic chip. A 4.5 cm microchannel was used to separate the mixture of AEMP and biotinylated AEMP. The present works indicated that AEMP has a good reactivity to the analytes containing carboxyl group with a similar ECL efficiency to TPA. Under optimal condition, the detection limits (based on 3 S/N) of AEMP was 2.7 microM. The system was also validated by the reaction between biotin and avidin. The calculated binding ratio between avidin and biotin based on the present method was 4.4.

Aminocaproates↗

PubMed2005

[Usefulness of serum inhibin B measurement for evaluation of ovarian reserve in controlled ovarian hyperstimulation].

OBJECTIVE: To assess usefulness of serum inhibin B (INHB) measurement for evaluation of ovarian function. METHODS: Serum INHB level on day 3 of menstrual cycle was determined by enzyme labeled immunosorbent assay (ELISA) in 96 cases of in vitro fertilization and embryo transfer (IVF-ET). The patients were classified into 3 groups including (1) poor response (n = 6), normal response (n = 72), and over response (n = 18) according to their response to ovary stimulation. In addition, serum follicle-stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E(2)) levels were also determined by chemiluminescent microparticle immunoassay in these patients. Evaluation of the INHB measurement and related factors was performed by statistical analysis. RESULTS: Serum INHB levels in poor, normal and over-response groups were (28 +/- 20), (85 +/- 42), (92 +/- 34) pg/ml; FSH levels were (11.9 +/- 5.3), (7.5 +/- 2.6), (7.2 +/- 1.7) U/L; E(2) levels on day 3 of human chorionic gonadotropin (hCG) administration were (2558 +/- 2108), (9366 +/- 4472), (18 392 +/- 9655) pmol/L; numbers of retrieved oocytes per cycle were (0.6 +/- 0.4), (8.7 +/- 3.6), (14.3 +/- 2.9); top grade embryos were (0.4 +/- 0.3), (3.8 +/- 1.9), (4.6 +/- 1.7); pregnancy rates were 16.7%, 36.1%, 61.1%, respectively. INHB level was negatively correlated to FSH (r = -0.222, P < 0.05) and FSH/LH (r = -0.371, P < 0.05); while positively correlated to E(2) on the day of hCG administration (r = 0.336, P < 0.05), number of retrieved oocytes (r = 0.404, P < 0.05), number of quality embryos (r = 0.323, P < 0.05) and pregnancy rate (r = 0.246, P < 0.05), respectively. CONCLUSIONS: INHB test may reflect the ovarian reserve which is of clinic importance in the guidance of controlled ovarian hyperstimulation.

Adult↗

PubMed2005

[Preparation and property of recombinant human bone morphogenetic protein-2 loaded hydrogel nanospheres and their biological effects on the proliferation and differentiation of bone mesenchymal stem cells].

PURPOSE: To prepare and study the recombinant human bone morphogenetic protein-2 loaded dextran-based hydrogel nanospheres (rhBMP(2)-dex-NPs) sustained release system, and to evaluate its biological effects on cultured rabbit bone mesenchymal stem cells(BMSCs). METHODS: The rhBMP(2)-dex-NPs were prepared by improved emulsion polymerization method. Their morphology, size and size distribution, encapsulated ratio and stability were assessed by routine procedure. Dynamic dialysis method was used to determine the release characteristics of rhBMP(2)-dex-NPs in vitro. Cell culture technique and MTT colorimetric assay were used to evaluate the proliferation and differentiation of the BMSCs, ALP kit was used to evaluate the ALP activity of the BMSCs so as to show the differentiation of the cells by adding the rhBMP(2)-dex-NPs to the DMEM culture medium (B group) or rhBMP2 only (A group). Adding dex-NPs without rhBMP2 (C group) and adding nothing (D group) were taken as the controls. The results were analyzed by statistical analysis software (SPSS10.0). RESULTS: The shape of rhBMP(2)-dex-NPs was spherical, with a size distribution of 20 nm. The encapsulated ratio was 83% and rhBMP(2)-dex-NPs could be kept more than 6 months under 4 degrees C without decomposition , destruction or deposition. The release profile in vitro was in accordance with two phases kinetics law, and more than 80% of the encapsulated rhBMP(2) can be released during 12 days. Statistical analysis showed that rhBMP(2)-dex-NPs had biological activity, and could enhance both proliferation and differentiation of rabbit BMSCs significantly, the effect of the rhBMP(2)-dex-NPs was significantly higher than that of rhBMP(2) (P<0.01). During the first 3 days, the proliferation and differentiation of BMSCs between group A and B had no significance (P>0.05), but much faster than group C and D. After 5 to 7 days, rhBMP(2)-dex-NPs could enhance BMSCs proliferation and differentiation continually, but rhBMP2 had no enhancement any more. 7 days later, the difference between group A and B become much more significant (P<0.001). CONCLUSIONS: The rhBMP(2)-dex-NPs can release rhBMP2 more than 12 days and have long-drawn biological effects. To encapsulate rhBMP2 into dextran-based hydrogel nanospheres may be an effective way of growth factor controlled release in tissue engineering.

Animals↗

PubMed2005

[Regulative action of acupuncture and moxibustion on mucosal immunity].

OBJECTIVE: To explore the regulative action of acupuncture and moxibustion on mucosal immunity and its curative effect on mucosal relative diseases. METHODS: Review the recent 10 years' achievements of studies on mucosal immunity and analyze the regulative action of acupuncture and moxibustion on the mucosal immunological system in treatment of mucosal relative diseases. CONCLUSION: Acupuncture and moxibustion has a good regulative action on local mucosal immunological system, which is one of the mechanisms of acupuncture and moxibustion in prevention and treatment of mucosal relative diseases. This proves a more reliable basis for treatment of mucosal relative diseases with acupuncture and moxibustion.

Acupuncture↗

PubMed2005

[Preparation of enamel matrix proteins controlled release microspheres and their biological effects on the proliferation and differentiation of human periodontal ligament cells in vitro].

OBJECTIVE: To prepare enamel matrix proteins (EMPs) loaded dextran-based hydrogel microspheres (EMPs-dex-MPs), and to evaluate their EMPs controlled release property and their biological effects on the proliferation and differentiation of human periodontal ligament cells (PDLCs) in vitro. METHODS: Using dimethylbenzene as the oil phase, EMPs-dex-MPs were achieved by emulsion-chemical crosslinking technique. The process of the recombination preparation was optimized by orthogonal factorization method. The configuration and size of EMPs-dex-MPs were determined by scanning electron microscope. The EMPs loading content and encapsulation rate of EMPs-dex-MPs, and their biodegradation characteristic were studied by routine analysis methods. Dynamic dialysis method was used to determine the release characteristic of EMPs-dex-MPs in vitro and its influencing factors. The proliferation of cultured PDLCs was measured by MTF method and the differentiation of PDLCs was measured by their alkaline phosphatase (ALP) activities. RESULTS: The results showed that EMPs-dex-MPs were homogenous and stable with the average diameter 25 microm, and the EMPs loading content was (32.8 +/- 1.2)%, the encapsulation rate was (78.9 +/- 1.0)%. Under 9% physiological saline solution contained a very thimbleful quantity of dextranase EMPs-dex-MPs could be biodegraded completely during about 40 days. The in vitro experiments showed that about 80% of EMPs could be released out in 20 days. Using EMPs-dex-MPs could enhance the proliferation responses and ALP activities of PDLCs more than 12 days. CONCLUSION: As a new sustained release system of growth factors, the dex-MPs is stable, workable and biodegradable. EMPs-dex-MPs, whose drug release can be controlled by preparation technique, may be more effective in promoting periodontal tissue regeneration.

Cell Differentiation↗

PubMed2004

Hsp90/p50cdc37 is required for mixed-lineage kinase (MLK) 3 signaling.

Mixed-lineage kinase 3 (MLK3) is a mitogen-activated protein kinase (MAPK) kinase kinase that activates MAPK pathways, including the c-Jun NH(2)-terminal kinase (JNK) and p38 pathways. MLK3 and its family members have been implicated in JNK-mediated apoptosis. A survey of human cell lines revealed high levels of MLK3 in breast cancer cells. To learn more about MLK3 regulation and its signaling pathways in breast cancer cells, we engineered the estrogen-responsive human breast cancer cell line, MCF-7, to stably, inducibly express FLAG epitope-tagged MLK3. FLAG.MLK3 complexes were isolated by affinity purification, and associated proteins were identified by in-gel trypsin digestion followed by liquid chromatography/tandem mass spectrometry. Among the proteins identified were heat shock protein 90alpha,beta (Hsp90) and its kinase-specific co-chaperone p50(cdc37). We show that endogenous MLK3 complexes with Hsp90 and p50(cdc37). Further experiments demonstrate that MLK3 associates with Hsp90/p50(cdc37) through its catalytic domain in an activity-independent manner. Upon treatment of MCF-7 cells with geldanamycin, an ansamycin antibiotic that inhibits Hsp90 function, MLK3 levels decrease dramatically. Furthermore, tumor necrosis factor alpha-induced activation of MLK3 and JNK in MCF-7 cells is blocked by geldanamycin treatment. Our finding that geldanamycin treatment does not affect the cellular levels of the downstream signaling components, MAPK kinase 4, MAPK kinase 7, and JNK, suggests that Hsp90/p50(cdc37) regulates JNK signaling at the MAPK kinase kinase level. Previously identified Hsp90/p50(cdc37) clients include oncoprotein kinases and protein kinases that promote cellular proliferation and survival. Our findings reveal that Hsp90/p50(cdc37) also regulates protein kinases involved in apoptotic signaling.

Apoptosis↗

PubMed2004

Quasi-phase-matched generation of tunable blue light in a quasi-periodic structure.

We present what is to our knowledge a new approach to generating tunable blue light by cascaded nonlinear frequency conversion in a single LiTaO3 crystal. Simultaneous quasi-phase matching of an optical parametric generation process and a sum-frequency mixing process is achieved by means of structuring the crystal with a quasi-periodic optical superlattice. The spectral (wavelength tuning and bandwidth) and power characteristics of the blue-light generation are studied with a fixed-wavelength 532-nm picosecond laser and a wavelength-tunable nanosecond optical parametric oscillator (OPO) as the pump sources. By tuning the OPO wavelength, we could tune the blue output over approximately 20 nm. Temperature tuning of the blue output at a fixed pump wavelength of 532 nm was limited to approximately 1.5 nm. A maximum blue power of 15 microW was generated at a pump power of 0.5 mW, corresponding to an efficiency of 3%.

Journal Article↗

PubMed2004

Direct electrochemical detection of glucose in human plasma on capillary electrophoresis microchips.

We developed an electrochemical detector on a hybrid chip for the determination of glucose in human plasma. The microchip system described in this paper consists of a poly(dimethylsiloxane) (PDMS) layer containing separation and injection channels and an electrode plate. The copper microelectrode is fabricated by selective electroless deposition. The fabrication of the decoupler is performed by platinum electrochemical deposition on the metal film formed by electroless deposition. Factors influencing the performance, including detection potential, separation field strength, and buffer concentration, were studied. The electrodes exhibited good stability and durability in the analytical procedures. Under optimized detection conditions, glucose responded linearly from 10 microM to 1 mM. Finally, glucose in human plasma from three healthy individuals and two diabetics was successfully determined, giving a good prospect for a new clinical diagnostic instrument.

Blood Glucose↗