PubMed Health⌕ Search

Biomedical subjects

Ying Peng

Publications and source records attributed to Ying Peng.

At least 37 records · Page 2Linked to original sources
PubMed2005

Rational design of an EGF-IL18 fusion protein: implication for developing tumor therapeutics.

Interleukin-18 (IL-18) is a proinflammatory cytokine. This protein has a role in regulating immune responses and exhibits significant anti-tumor activities. Epidermal growth factor (EGF) is an important growth factor that plays a central role in the regulation of cell cycle and differentiation. It was proposed that a targeted delivery of IL-18 by generation of IL-18-EGF fusion protein might decrease adverse effects and result in enhancing cytotoxic and antitumor activities. In the present study, a fusion protein, consisting of EGFR binding domain fused to human IL-18 mature peptide via a linker peptide of (Gly(4)Ser) 3, was constructed and expressed in the insect cell line Sf9 using Bac-to-Bac baculovirus expression system. We showed that the purified recombinant fusion protein induced similar levels of IFN-gamma to that of native IL-18 protein in human PBMC in the presence of ConA. Furthermore, EGF receptor competitive test in human epithelial cancer A431 cell line showed that EGF-IL18 fusion protein can specifically bind with EGFR by competing with native EGF protein. These suggest that this rationally designed protein can be further developed as novel tumor therapeutics.

Animals↗
PubMed2005

Ascorbic acid inhibits ROS production, NF-kappa B activation and prevents ethanol-induced growth retardation and microencephaly.

In this study, we established an embryo model to study the effects of ethanol on fetal development. When embryos of Xenopus laevis (the African clawed frog) were exposed to ethanol, the resultant tadpoles had significantly reduced brain sizes (microencephaly) and retarded growth rates. These effects, similar to those observed in human fetal alcohol syndrome (FAS), were dose- and time-dependent. We further showed that the antioxidant ascorbic acid (vitamin C) could inhibit the ethanol-induced reactive oxygen species (ROS) production and NF-kappaB activation and protect the ethanol-treated embryos against microencephaly and growth retardation. These results suggest the involvement of NF-kappaB and oxidative stress in ethanol-mediated developmental defects, and the potential use of ascorbic acid as a new and effective protective agent for FAS.

Animals↗
PubMed2005

In-channel indirect amperometric detection of nonelectroactive anions for electrophoresis on a poly(dimethylsiloxane) microchip.

In the present paper, we describe a microfluidics-based sensing system for nonelectroactive anions under negative separation electric field by mounting a single carbon fiber disk working electrode (WE) in the end part of a poly(dimethylsiloxane) microchannel. In contrast to work in a positive separation electric field described in our previous paper (Anal. Chem. 2004, 76, 6902-6907), here the electrochemical reduction reaction at the WE is not coupled with the separation high-voltage (HV) system, whereas the electrochemical oxidation reaction at the WE is coupled with the separation HV system. The electroactive indicator is the carbon fiber WE itself but not dissolved oxygen. This provides a convenient and sensitive means for the determination of nonelectroactive anions by amperometry. The influences of separation voltage, detection potential, and the distance between the WE and the separation channel outlet on the response of the detector have been investigated. The present detection mode is successfully used to electrochemically detect F-, Cl-, SO4(2-), CH3COO-, H2PO4-. Based on the preliminary results, a detection limit of 2 microM and a dynamic range up to three orders of magnitude for Cl- could be achieved.

Anions↗
PubMed2005

Effects of insulin-like growth factor-1 on okadaic acid-induced apoptosis in SH-SY5Y cells.

The effects of insulin-like growth factor-1 (IGF-1) on the cytotoxicity and apoptosis induced by okadaic acid (OA) in SH-SY5Y cells were investigated. Cell viability was measured using the MTT (3-(4,5-dimethylthiazolyl-2)-2,-5-diphenyltetrazolium bromide) assay. Early and late apoptosis/necrosis were analyzed by flow cytometry using Annexin V and propidium iodide (PI) double-staining. Caspase-3 activation was detected by Western blot analysis. Preincubation with IGF-1 for 24 h prevented cytotoxicity induced by 40 nM OA given for 24 h, and the MTT value significantly increased. Incubation with 20 nM OA for 24 h caused a marked increase in the percentage of early apoptotic and late apoptotic/necrotic cells, which was not dependent on the activation of caspase-3. OA-induced apoptosis was significantly decreased by pretreatment with 10 ng/ml of IGF-1 for 24 h. The results supported the hypothesis that IGF-1 may be useful in the treatment of Alzheimer's disease.

Annexin A5↗
PubMed2005

Expression, purification and crystal structure of a truncated acylpeptide hydrolase from Aeropyrum pernix K1.

Acylpeptide hydrolase (APH) catalyzes the N-terminal hydrolysis of Nalpha-acylpeptides to release Nalpha-acylated amino acids. The crystal structure of recombinant APH from the thermophilic archaeon Aeropyrum pernix K1 (apAPH) was reported recently to be at a resolution of 2.1 Angstrom; using X-ray diffraction. A truncated mutant of apAPH that lacks the first short alpha-helix at the N-terminal, apAPH-delta(1-21), was cloned, expressed, characterized and crystallized. Data from biochemical experiments indicate that the optimum temperature of apAPH is decreased by 15 degrees C with the deletion of the N-terminal alpha-helix. However, the enzyme activity at the optimal temperature does not change. It suggests that this N-terminal alpha-helix is essential for thermostability. Here, the crystal structure of apAPH-delta(1-21) has been determined by molecular replacement to 2.5 Angstrom;. A comparison between the two structures suggests a difference in thermostability, and it can be concluded that by adding or deleting a linking structure (located over different domains), the stability or even the activity of an enzyme can be modified.

Aeropyrum↗
PubMed2005

Gene therapy for bone regeneration.

Efficacious bone regeneration could revolutionize the clinical management of many bone and musculoskeletal disorders. Bone has the unique ability to regenerate and continuously remodel itself throughout life. However, clinical situations arise when bone is unable to heal itself, as with segmental bone loss, fracture non-union, and failed spinal fusion. This leads to significant morbidity and mortality. Current attempts at improved bone healing have been met with limited success, fueling the development of improved techniques. Gene therapy in many ways represents an ideal approach for augmenting bone regeneration. Gene therapy allows specific gene products to be delivered to a precise anatomic location. In addition, the level of transgene expression as well as the duration of expression can be regulated with current techniques. For bone regeneration, the gene of interest should be delivered to the fracture site, expressed at appropriate levels, and then deactivated once the fracture has healed. Delivery of biological factors, mostly bone morphogenetic proteins (BMPs), has yielded promising results both in animal and clinical studies. There has also been tremendous work on discovering new growth factors and exploring previously defined ones. Finally, significant advances are being made in the delivery systems of the genes, ranging from viral and non-viral vectors to tissue engineering scaffolds. Despite some public hesitation to gene therapy, its use has great potential to expand our ability to treat a variety of human bone and musculoskeletal disorders. It is conceivable that in the near future gene therapy can be utilized to induce bone formation in virtually any region of the body in a minimally invasive manner. As bone biology and gene therapy research progresses, the goal of successful human gene transfer for augmentation of bone regeneration draws nearer.

Animals↗
PubMed2005

[Eukaryotic expression and tumor-targeting modification of human mutated-IL-18 fusion gene].

Interleukin-18 (IL-18) is a proinflammatory cytokinin. This protein has a role in regulating immune responses and exhibits significant anti- tumor activities. Epidermal growth factor (EGF) is an important growth factor that plays a central role in the regulation of cell cycle and differentiation. It was proposed that a targeted delivery of IL-18 by generation of IL-18-EGF fusion protein might decrease adverse effects and result in enhancing cytotoxic and antitumor activities. In the present study, a fusion protein, consisting of EGFR binding domain fused to human IL18 mature peptide via a linker peptide of (Gly4ser) 3, was constructed and expressed in the insect cell line Sf9 using Bac-to-Bac baculovirus expression system. We showed that the purified recombinant fusion protein induced similar levels of IFN-gamma to that of native IL-18 protein in human PBMC in the presence of ConA. Furthermore, EGF Receptor competitive test in human epithelial cancer A431 cell line showed that EGF- IL18 fusion protein can specifically bind with EGFR by competing with native EGF protein. The results suggested that EGF-IL18 fusion protein could specifically be targeted on tumor cells. The work may provide a new insight into the cytokinin for the tumor treatment.

Animals↗
PubMed2005

[Effective inhibition of EB virus-encoded latent membrane protein-1 by siRNA in EB virus (+) nasopharyngeal carcinoma cell].

OBJECTIVE: To evaluate the application of RNA interference in the study of latent membrane protein-1 (LMP-1) in EB virus-positive nasopharyngeal carcinoma (NPC) cell line C611. Observe the effects of LMP-1 silencing on NPC cell growth. METHODS: Four synthesized small interference RNA (siRNA) were transfected into NPC cell using Oligofectamine reagent. LMP-1 mRNA level was determined by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR). Flow cytometry and MTT assay were employed to analyze the effects on cell cycle and proliferation. RESULTS: The most effective sequence found out among the 4 candidates. Single dose of this siRNA caused nearly 90% loss of LMP-1 mRNA in C611 cell. The specific inhibition could last for 96 hours if re-transfection was preformed. LMP-1 siRNA treatment resulted in cell cycle arrest at G0-G1 stage in C611, accompany with a reduction of cell proliferation by 32.9%. While EBV-negative NPC cells appeared unaffected. CONCLUSIONS: These results provided solid testimony that EBV-encoded latent membrane protein-1 was vulnerable to RNA interference and, selective inhibition of LMP-1 had anti-proliferation effect on NPC cell. RNA interference could be a powerful tool in further investigations of LMP-1 and a novel therapeutic strategy for EBV-related NPC patients.

Cell Line, Tumor↗
PubMed2005

[Adeno-associated virus-mediated gene transfer of endostatin for inhibiting growth and metastasis of human nasopharyngeal carcinoma in nude mice].

OBJECTIVE: To investigate the inhibitory effect on growth and metastasis of human nasopharyngeal carcinoma in nude mice by adeno-associated virus-mediated gene transfer of human endostatin. METHODS: The infectious efficiency of recombinant adeno-associated virus (rAAV) in vitro was detected. The endostatin expressed in human umbilical vein endothelial cell ECV304 was detected by immunofluorescence staining. MTT was used to assay inhibitory effect of the infecting supernatant of recombinant adeno-associated viral vectors carrying human endostatin gene (rAAV-hEndo)on ECV304 cell. Heterotopic implantation model of human nasopharyngeal carcinoma cell C666-1 in nude mice was established. rAAV-hEndo or rAAV-EGFP or PBS were injected into the tail vein of tumor bearing mice. Three weeks after implantation, the volumes of tumor, inhibition rate, the percentage of lung metastases, microvessel density (MVD) and apoptotic index (AI) were evaluated respectively. RESULTS: The infectious efficiency of rAAV was 98% in vitro. Immunofluorescence staining showed the humam endostatin protein was expressed mainly in cytoplasm. ECV304 cell proliferation was obviously inhibited by the infecting supernatant of rAAV-hEndo. The inhibitory rate was 67.3% when the supernatant was used 72 h later. Compared with PBS group, the restrained percentage of tumor in hEndo group was 70.7%. The percentage of lung metastases in hEndo group, EGFP group and PBS group was 0.0%, 50.0% and 66.7% respectively. The average MVD of hEndo group (3.67 +/- 1.63) was significantly lower than that of EGFP group (19.67 +/- 2.16) and PBS group (22.50 +/- 3.02) (P < 0.01). The apoptotic index increased significantly in hEndo group(28.83 +/- 5.27)% versus EGFP group (6.17 +/- 2.79)% and PBS group (4.50 +/- 2.17)% (P < 0.01). The survival time of tumor bearing mice in hEndo group (36.50 +/- 8.46) d was significantly longer than EGFP group (24.00 +/- 5.66) d and PBS group (21.17 +/- 3.92) d (P < 0.01). CONCLUSIONS: The gene transfer of human endostatin mediated by adeno-associate virus can inhibit the growth and metastasis of human nasopharyngeal carcinoma in nude mice effectively. The mechanism may be due to the effect of antiangiogensis and inducement of tumor cell apoptosis.

Animals↗
PubMed2004

Electrochemical detection method for nonelectroactive and electroactive analytes in microchip electrophoresis.

In this work, we establish an indirect amperometric detection method via mounting a single carbon fiber disk working electrode in the end part of a microchannel. This in-channel configuration for microchip capillary electrophoresis brings about that the potential of the working electrode in the case of electrochemical reduction reaction is coupled by the separation electric field, while the potential of the working electrode in the case of electrochemical oxidation reaction is not coupled by the separation electric field. Such a special performance provides a convenient and sensitive approach for indirectly detecting nonelectroactive analytes that relies on amperometric response of dissolved oxygen in solution and directly detecting electroactive analytes based on their own amperometric response on the carbon fiber electrode. This method has shown its essential importance in the analysis of inorganic cations, biomolecules, and electroosmotic flow rates. Based on preliminary results, a detection limit of 1.0 microM for K(+) and Na(+) have been achieved.

Carbon↗
PubMed2004

Connective tissue growth factor (CTGF) is regulated by Wnt and bone morphogenetic proteins signaling in osteoblast differentiation of mesenchymal stem cells.

Osteoblast lineage-specific differentiation of mesenchymal stem cells is a well regulated but poorly understood process. Both bone morphogenetic proteins (BMPs) and Wnt signaling are implicated in regulating osteoblast differentiation and bone formation. Here we analyzed the expression profiles of mesenchymal stem cells stimulated with Wnt3A and osteogenic BMPs, and we identified connective tissue growth factor (CTGF) as a potential target of Wnt and BMP signaling. We confirmed the microarray results, and we demonstrated that CTGF was up-regulated at the early stage of BMP-9 and Wnt3A stimulations and that Wnt3A-regulated CTGF expression was beta-catenin-dependent. RNA interference-mediated knockdown of CTGF expression significantly diminished BMP-9-induced, but not Wnt3A-induced, osteogenic differentiation, suggesting that Wnt3A may also regulate osteoblast differentiation in a CTGF-independent fashion. However, constitutive expression of CTGF was shown to inhibit both BMP-9- and Wnt3A-induced osteogenic differentiation. Exogenous expression of CTGF was shown to promote cell migration and recruitment of mesenchymal stem cells. Our findings demonstrate that CTGF is up-regulated by Wnt3A and BMP-9 at the early stage of osteogenic differentiation, which may regulate the proliferation and recruitment of osteoprogenitor cells; however, CTGF is down-regulated as the differentiation potential of committed pre-osteoblasts increases, strongly suggesting that tight regulation of CTGF expression may be essential for normal osteoblast differentiation of mesenchymal stem cells.

Adenoviridae↗
PubMed2004

Coupled oscillators control morning and evening locomotor behaviour of Drosophila.

Daily rhythms of physiology and behaviour are precisely timed by an endogenous circadian clock. These include separate bouts of morning and evening activity, characteristic of Drosophila melanogaster and many other taxa, including mammals. Whereas multiple oscillators have long been proposed to orchestrate such complex behavioural programmes, their nature and interplay have remained elusive. By using cell-specific ablation, we show that the timing of morning and evening activity in Drosophila derives from two distinct groups of circadian neurons: morning activity from the ventral lateral neurons that express the neuropeptide PDF, and evening activity from another group of cells, including the dorsal lateral neurons. Although the two oscillators can function autonomously, cell-specific rescue experiments with circadian clock mutants indicate that they are functionally coupled.

Animals↗
PubMed2004

Synthesis and structures of aluminium monohydride and chalcogenides bearing a bidentate [N,O] ligand.

The aluminium monohydride (3-tBu-5-Me-2-(O)C(6)H(2)CH(2)-N-2,6-iPr(2)C(6)H(3))AlH(NMe(3))(2) was prepared by treatment of the bidentate salicylaldimine [3-tBu-5-Me-2-(OH)C(6)H(2)CH=N-2,6-iPr(2)C(6)H(3)](1) with a small excess of AlH(3).NMe(3) in high yield. Compound 2 reacted with sulfur and selenium respectively to afford the dimeric aluminium chalcogenide [(3-tBu-5-Me-2-(O)C(6)H(2)CH(2)-NH-2,6-iPr(2)C(6)H(3))Al(micro-E)](2)[E = S (3), E = Se (4)]. During the formation of 2 hydrogen migration from the aluminium centre to the ligand backbone occurred. A possible reaction mechanism for 3 and 4 is discussed and the molecular structures of compounds 2-4 were determined by X-ray structural analyses.

Journal Article↗
PubMed2004

Protection of Xenopus laevis embryos against alcohol-induced delayed gut maturation and growth retardation by peroxiredoxin 5 and catalase.

Accumulated evidence indicates that maternal alcohol consumption causes fetal enteric damage and growth retardation. In this study, we investigated the underlying molecular mechanisms in a Xenopus model of fetal alcohol exposure. We established a condition of transient alcohol exposure that produces tadpoles with delayed gut maturation and decreased body length. We then investigated the roles of reactive oxygen species (ROS) and reactive nitrogen species (RNS) by microinjecting plasmids expressing catalase and peroxiredoxin 5 (PRDX5) into two-cell stage embryos. Finally, the effects of these enzymes on the expression of key gut developmental genes were determined by animal cap explant assay. We showed that exposure of Xenopus embryos to 0.5% alcohol from stage 13 to stage 22 produced tadpoles with delayed gut maturation, reduced growth, and down-regulation in several gut developmental genes, with VegT, Pax6 and Sox17 most vulnerable. We further demonstrated that microinjection of catalase attenuated alcohol-induced ROS production and restored the expression of VegT and Pax6, but protected the embryos from delayed gut development and retarded growth only partially. By contrast, microinjection of PRDX5 reduced both ROS and RNS production, and prevented the gut and growth defects, and restored VegT, Pax6 and Sox17 gene expression. A positive correlation was found between delayed gut maturation and reduced body length. These results indicate the crucial roles of both the ROS-Pax6 and RNS-Sox17 signaling axes in alcohol-induced fetal gut defects and growth retardation. In addition, they suggest strongly a cause-and-effect relationship between alcohol-induced delayed gut maturation and growth retardation.

Animals↗
PubMed2004

Inhibitor of DNA binding/differentiation helix-loop-helix proteins mediate bone morphogenetic protein-induced osteoblast differentiation of mesenchymal stem cells.

Bone morphogenetic proteins (BMPs) belong to the TGF-beta superfamily and play an important role in development and in many cellular processes. We have found that BMP-2, BMP-6, and BMP-9 induce the most potent osteogenic differentiation of mesenchymal stem cells. Expression profiling analysis has revealed that the Inhibitors of DNA binding/differentiation (Id)-1, Id-2, and Id-3 are among the most significantly up-regulated genes upon BMP-2, BMP-6, or BMP-9 stimulation. Here, we sought to determine the functional role of these Id proteins in BMP-induced osteoblast differentiation. We demonstrated that the expression of Id-1, Id-2, and Id-3 genes was significantly induced at the early stage of BMP-9 stimulation and returned to basal levels at 3 days after stimulation. RNA interference-mediated knockdown of Id expression significantly diminished the BMP-9-induced osteogenic differentiation of mesenchymal progenitor cells. Surprisingly, a constitutive overexpression of these Id genes also inhibited osteoblast differentiation initiated by BMP-9. Furthermore, we demonstrated that BMP-9-regulated Id expression is Smad4-dependent. Overexpression of the three Id genes was shown to promote cell proliferation that was coupled with an inhibition of osteogenic differentiation. Thus, our findings suggest that the Id helix-loop-helix proteins may play an important role in promoting the proliferation of early osteoblast progenitor cells and that Id expression must be down-regulated during the terminal differentiation of committed osteoblasts, suggesting that a balanced regulation of Id expression may be critical to BMP-induced osteoblast lineage-specific differentiation of mesenchymal stem cells.

Adenoviridae↗
PubMed2004

Phosphatidylinositol 3-kinase signaling is involved in neurogenesis during Xenopus embryonic development.

Phosphatidylinositol 3-kinase (PI3K) has numerous cellular functions, including cell survival and proliferation. In this study, we demonstrated that the expression of the active form of PI3K induced dorsal differentiation and axis duplication and strongly induced the expression of neural markers. In contrast, the inhibition of PI3K activity by its dominant negative mutant induced the phenotype of losing posterior structures and the expression of ventral markers. Akt is an essential target of PI3K for neurogenesis. The expression of the active form of Akt induced axis duplication and increased the expression of neural markers. Inhibition of the Akt activity abolished the PI3K-induced double heads and axes. This signal transmits through its target, glycogen synthase kinase 3beta, which is known to mediate Wnt signaling for Xenopus development. These results identify a new function of PI3K/Akt signaling in axis formation and neurogenesis during Xenopus embryonic development and provide a direct link between growth factor-mediated PI3K/Akt signaling and Wnt signaling during embryonic development.

Animals↗