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Peng Wu

Publications and source records attributed to Peng Wu.

30 records · Page 2Linked to original sources
PubMed2004

Two-step chromatographic method for separation and purification of nerve growth factor from venom of Chinese cobra.

By selecting the different combination schemes, a simple, fast and highly efficient method for separation and purification of nerve growth factor (NGF) from venom of Chinese cobra is reported in this paper. This purification process consists of a two-step chromatographic separation on DEAE-Sepharose F.F. anion-exchange medium followed by a Sephadex G-50 gel filtration. On reducing and non-reducing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), the nerve growth factor obtained with this process proved to be homogeneous and its molecular weight was separately estimated to be approximately 14.5 and 29.0kD, which was consistent with that reported in literature; and on high performance size-exclusion chromatography and reversed-phase chromatography, its purity was about 99%. The yield of this purification method was 0.51% and the nerve growth factor obtained had the activity of eliciting neurite outgrowth from chick embryonic dorsal root ganglia. The optimum concentration of nerve growth factor was 5-100ng/ml and the minimal concentration eliciting neurite outgrowth from chick embryonic dorsal root ganglia was 5.0 ng/ml.

Chromatography, Liquid↗
PubMed2004

[A new chromatographic method for separation and purification of nerve growth factor from venom of Chinese Cobra].

In order to find a simple, fast and highly efficient method for the separation and purification of nerve growth factor (NGF) from venom of Chinese Cobra, the combination process of several different kinds of chromatographic media was studied. According to the properties of NGF and the character of different chromatographic media, a novel two-step chromatographic purification method, consisting of chromatography of crude venom on DEAE-Sepharose F. F. anion-exchange medium followed by a size exclusion on a Sephadex G-50 column, is presented. The DEAE-Sepharose F. F. chromatographic column was 20 cm x 3.5 cm i.d. and first eluted with 50 mmol/L Tris-HCl (pH 8.5) for 50 min, and separately followed by an elution with a linear gradient of 0 - 200 mmol/L NaCl containing 50 mmol/L Tris-HCl (pH 8.5) for 190 min and with 200 mmol/L NaCl containing 50 mmol/L Tris-HCl (pH 8.5) for 60 min. The flow rate of mobile phase was 6.1 mL/min. The Sephadex G-50 column was 150 cm x 3.5 cm i.d. and eluted with 50 mmol/L phosphate-buffered saline (PBS) (pH 7.5) for 1 250 min. The flow rate of elution solution was 2.4 mL/min. Through this two-step chromatographic purification process, the obtained NGF was proved to be homogeneous on sodium-dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and its relative molecular mass was estimated to be approximately 29 000, which was consistent with that reported in literature. On a Shim-Pack VP-ODS reversed-phase high performance chromatographic column (4.6 mm i.d. x 150 mm), its purity was about 98.3%. The total protein recovery of this purification method was 0.51% and the obtained NGF had the activity of eliciting neurite outgrowth from chick embryonic dorsal root ganglia. This two-step chromatographic process is simple and highly efficient. It can be used to isolate and purify NGF from venom of Chinese Cobra in large-scale.

Animals↗
PubMed2003

[Selection of the imaging modalities for diagnosis of renal trauma: experience with 74 cases].

OBJECTIVE: To explore the diagnostic approaches and values of the imaging modalities for traumatic renal injuries. METHODS: The clinical records of 74 cases of renal trauma treated in Nanfang Hospital were retrospectively reviewed to assess the diagnostic value of intravenous urography (IVU), type B ultrasonography and computed tomography (CT). RESULTS: The positivity rates by IVU, type B ultrasonography, and CT were 89% (43/49), 80% (55/68) and 100% (51/51) respectively for the diagnosis of renal trauma. CONCLUSION: IVU is rapid and convenient, ultrasonography less costly and invasive, and CT accurate for diagnosis of renal traumas.

Adolescent↗
PubMed2002

Characterization and thermodynamic properties of quadruplex/duplex competition.

Structural characteristics and thermodynamic properties of dG(3)(T(2)AG(3))(3), d(C(3)TA(2))(3)C(3) and dG(3)(T(2)AG(3))(3)/d(C(3)TA(2))(3)C(3) were intensively investigated. It was indicated that metal ions greatly affected the conformation and stability of the G-quadruplex. A competition of a structure transition among the G-quadruplex, I-motif, and the duplex was confirmed to be dependent on both cation species and pH values. The structural competitive mechanism is discussed for the first time. This study shows an intriguing potential in modulating DNA structures in vivo, which is of great importance in drug design and cancer chemotherapy.

Calorimetry↗
PubMed2002

Structural and dynamic features of Alzheimer's Abeta peptide in amyloid fibrils studied by site-directed spin labeling.

Electron paramagnetic resonance spectroscopy analysis of 19 spin-labeled derivatives of the Alzheimer's amyloid beta (Abeta) peptide was used to reveal structural features of amyloid fibril formation. In the fibril, extensive regions of the peptide show an in-register, parallel arrangement. Based on the parallel arrangement and side chain mobility analysis we find the amyloid structure to be mostly ordered and specific, but we also identify more dynamic regions (N and C termini) and likely turn or bend regions (around residues 23-26). Despite their different aggregation properties and roles in disease, the two peptides, Abeta40 and Abeta42, homogeneously co-mix in amyloid fibrils suggesting that they possess the same structural architecture.

Alzheimer Disease↗
PubMed2002

Effect of divalent cations and cytosine protonation on thermodynamic properties of intermolecular DNA double and triple helices.

The contribution of divalent cations and cytosine protonation to conformation and stability of duplex and triplex formation were intensively investigated and characterized by ultraviolet (UV), circular dichroism (CD), differential scanning calorimetry (DSC), and electrophoresis mobility shift assay (EMSA). CD spectra showed that the divalent cations investigated would not significantly distort nucleotide geometry, while UV and DSC melting experiments revealed that the cation binding abilities to duplexes and triplexes were clearly dependent on the types of cations under near physiological conditions. The calorimetric enthalpies were generally underestimated relative to the corresponding van't Hoff enthalpies for Hoogsteen and Watson-Crick transitions, but free energy changes derived from the DSC measurements were in good agreement with those derived from the UV measurements. The adjacent placing of the C(+) x G.C triplets in triplexes lowered the stabilities of not only Hoogsteen base-pairing but also Watson-Crick base-pairing. The protonation contribution of the given cytosine residues might depend on the local and global structure of the protonated cytosine complex. A rigid structural targeted-strand would favor the protonation of cytosine residues. The apparent pK(a) values for parallel duplex and triplex investigated were determined to be 6.4 and 7.6, respectively, which are considerably heightened by 2.1 and 3.3 pH unit as compared to the intrinsic pK(a) value of the free cytosine residues.

Calorimetry, Differential Scanning↗
PubMed2002

Temperature dependence of thermodynamic properties for DNA/DNA and RNA/DNA duplex formation.

A clear difference in the enthalpy changes derived from spectroscopic and calorimetric measurements has recently been shown. The exact interpretation of this deviation varied from study to study, but it was generally attributed to the non-two-state transition and heat capacity change. Although the temperature-dependent thermodynamics of the duplex formation was often implied, systemic and extensive studies have been lacking in universally assigning the appropriate thermodynamic parameter sets. In the present study, the 24 DNA/DNA and 41 RNA/DNA oligonucleotide duplexes, designed to avoid the formation of hairpin or slipped duplex structures and to limit the base pair length less than 12 bp, were selected to evaluate the heat capacity changes and temperature-dependent thermodynamic properties of duplex formation. Direct comparison reveals that the temperature-independent thermodynamic parameters could provide a reasonable approximation only when the temperature of interest has a small deviation from the mean melting temperature over the experimental range. The heat capacity changes depend on the base composition and sequences and are generally limited in the range of -160 to approximately -40 cal.mol-1.K-1 per base pair. In contrast to the enthalpy and entropy changes, the free energy change and melting temperature are relatively insensitive to the heat capacity change. Finally, the 16 NN-model free energy parameters and one helix initiation at physiological temperature were extracted from the temperature-dependent thermodynamic data of the 41 RNA/DNA hybrids.

Base Pairing↗
PubMed2002

Assessment of antiangiogenic effect using 99mTc-EC-endostatin.

PURPOSE: Tumor vascular density may provide a prognostic indicator of metastatic potential or survival. The purpose of this study was to develop 99mTc-ethylenedicysteine-endostatin (99mTc-EC-endostatin) for the evaluation of anti-angiogenesis therapy. METHOD: 99mTc-EC-endostatin was prepared by conjugating ethylenedicysteine (EC) to endostatin, followed by adding pertechnetate and tin chloride. Radiochemical purity was > 95%. In vitro cell viability, affinity and TUNEL assays were performed. Tissue distribution and planar imaging of radiolabeled endostatin were determined in tumor-bearing rats. To assess anti-angiogenic treatment response, rats were treated with endostatin, paclitaxel and saline, followed by imaging with 99mTc-EC-endostatin. Tumor response to endostatin therapy in tumor-bearing animal models was assessed by correlating tumor uptake dose with microvessel density, VEGF, bFGF and IL-8 expression during endostatin therapy. RESULTS: In vitro cell viability and TUNEL assays indicated no marked difference between EC-endostatin and endostatin. Cellular uptake assay suggests that endostatin binds to endostatin receptor. Biodistribution of 99mTc-EC-endostatin in tumor-bearing rats showed increased tumor-to-tissue count density ratios as a function of time. Tumor uptake (%ID/g) of 99mTc-EC-endostatin was 0.2-0.5. Planar images confirmed that the tumors could be visualized clearly with 99mTc-EC-endostatin. The optimal time for imaging using radiolabeled endostatin was 2 hrs. 99mTc-EC-endostatin could assess treatment response. There was a correlation between tumor uptake and cellular targets expression. CONCLUSION: The results indicate that it is feasible to use 99mTc-EC-endostatin to assess efficiency of anti-angiogenesis therapy.

Angiogenesis Inhibitors↗