Biomedical subjects

Qi Zheng

Publications and source records attributed to Qi Zheng.

26 records · Page 2Linked to original sources

PubMed2005

Nearby clusters of hemagglutinin residues sustain SLAM-dependent canine distemper virus entry in peripheral blood mononuclear cells.

Signaling lymphocytic activation molecule (SLAM, CD150) is the universal morbillivirus receptor. Based on the identification of measles virus (MV) hemagglutinin (H) amino acids supporting human SLAM-dependent cell entry, we mutated canine distemper virus (CDV) H and identified residues necessary for efficient canine SLAM-dependent membrane fusion. These residues are located in two nearby clusters in a new CDV H structural model. To completely abolish SLAM-dependent fusion, combinations of mutations were necessary. We rescued a SLAM-blind recombinant CDV with six mutations that did not infect ferret peripheral blood mononuclear cells while retaining full infectivity in epithelial cells.

Amino Acid Sequence↗

PubMed2005

[Vasoinhibitory effect of daltepartin sodium on human hepatocellular carcinoma in nude mice].

OBJECTIVES: To study the inhibition effect of Daltepartin Sodium (low molecular weight heparins) on human hepatocellular carcinoma (HCC) in nude mice. METHODS: Metastatic model of HCC was established in nude mice. The model mice were randomly divided into 4 groups; they were the control group (saline solution), chemotherapy group (fluorouracil and Cis-dichlorodiamine platinum), Daltepartin Sodium group (Daltepartin Sodium), combined treatment group (Daltepartin Sodium and chemotherapy). Tumor sizes, tumor inhibition rates, tumor metastases, intratumoral microvessel density (MVD), CD31 and AFP were evaluated. RESULTS: In comparison with the control and the chemotherapy group, the tumor sizes of the Daltepartin Sodium and the combined treatment group were significantly smaller; the tumor inhibitor rates were 0% versus 93.6%, 76.7%, 78.0%; MVD were 20.7+/-6.8 versus 18.2+/-2.6, 4.8+/-1.8 and 6.5+/-2.4; CD31 were 31.8+/-5.7 versus 25.5+/-5.1, 21.6+/-4.8 and 19.6+/-2.4; The incidence of liver metastasis was 80%, versus 70%, 20% and 10%; lung metastasis was 70% versus 60%, 20% and 10%; the peritoneal metastasis was 90% versus 60%, 30%and 30%. AFP were 121.8 ng/ml+/-31.4 ng/ml versus 21.5 ng/ml+/-13.3 ng/ml, 75.6 ng/ml+/-29.7 ng/ml and 55.8 ng/ml+/-38.0 mg/ml. Inhibiting effects of growth and metastasis of HCC in chemotherapy, Daltepartin Sodium and combined treatment groups were significantly different from those of the control group (F=9.191, P < 0.01), Daltepartin Sodium inhibited the angiogensis in the tumors more effectively than that in the control and chemotherapy groups (F=4.937, P < 0.01). CONCLUSION: Daltepartin Sodium can inhibit tumor growth and metastasis by inhibiting tumor angiogenesis in our nude mice HCC model.

Angiogenesis Inhibitors↗

PubMed2004

[Study on the ultraviolet-visible spectra of Au/Al2O3 catalysts].

A variety of synthesis parameters for the preparation of gold nanoparticles by NaBH4 solution reduction in the W/O microemulsion media consisting of Cetyl Trimethyl Ammonium Bromide (CTAB)/n-hexanol/water system was investigated. The results showed that the molar ratio of water to surfactant (rw) had nothing to do with the gold particle size, but the concentration of the aqueous gold salt solution had a significant effect on the size of gold particle. Through optimizing the preparation parameters, Au/Al2O3 catalysts were prepared with two different methods, then the catalysts were characterized by ultraviolet-visible spectra, XRD and TEM, and the effect of two different preparation methods on active component gold particle size in the catalysts was studied.

English Abstract↗

PubMed2004

[Diffusion reflectance spectroscopy of ZrO2 phase structure].

Diffusion Reflectance Spectroscopy (DRS) was employed to study the surface phase structure of ZrO2-based catalysts. The effect of calcining temperature, and the addition of Al2O3 and platinum on the surface and bulk phase structures of zirconia was studied by DRS combined with XRD, DTA and XPS. The same trend was observed that heating to higher temperatures results in the conversion to monoclinic zirconia in undoped samples, while incorporation of an appropriate amount of Al2O3 would stabilize the tetragonal phase zirconia. And the reduction processing of Pt/ZrO2 affects crystallization and phase transitions, resulting in certain fraction of tetragonal ZrO2 transferred to monoclinic ZrO2. The DRS shows an appreciable difference in the corresponding XRD spectra that more monoclinic zirconia formed on the surface of catalyst during the reduction processing of Pt/ZrO2, compared to the bulk of catalyst.

Diffusion↗

PubMed2003

Mathematical issues arising from the directed mutation controversy.

During the past 14 years or so a large body of new evidence that supposedly supports the directed mutation hypothesis has accumulated. Interpretation of some of the evidence depends on mathematical reasoning, which can be subtler than it appears at first sight. This article attempts to clarify some of the mathematical issues arising from the directed mutation controversy, thereby offering alternative interpretations of some of the evidence.

Data Interpretation, Statistical↗

PubMed2003

The effect of the EAAEAE insert on the property of human metallothionein-3.

MT3 shows apparently different properties and function from MT1 even though they have 70% sequence homology. Possibly the two inserts, Thr5 and a negatively charged hexapeptide at position-55 in MT3, play important roles. A series of MT3 variants around the EAAEAE hexapeptide have been prepared by site-directed mutagenesis and their properties and reactivity towards pH, EDTA and DTNB have been studied. Our detailed studies revealed that the EAAEAE insert is essential to the property of MT3. It is the hexapeptide insert, to some extent, making the MT3 alpha-domain looser and lower stability of the metal-thiolate cluster, which could be accessed more easily.

Dithionitrobenzoic Acid↗

PubMed2002

Statistical and algorithmic methods for fluctuation analysis with SALVADOR as an implementation.

This paper aims at removing certain long-standing impediments to more effective and widespread use of fluctuation analysis. The paper presents a method of constructing confidence intervals for mutation rates using data from fluctuation experiments. The method was inspired by a rediscovery of a little-known, not fully developed method of Lea and Coulson; substantial modifications have been made both to enhance computational efficiency and to widen the scope of the original method's applicability. A computer package named SALVADOR is presented that can be used for Monte Carlo simulation, for point and interval estimation of mutation rates, and for exploration of various hypotheses spawned by the directed mutation controversy. In addition to the maximum likelihood method, methods of considerable historical interest are also examined and included in SALVADOR to help the reader compare and assess some of the most popular methods for estimating mutation rates.

Algorithms↗

PubMed2002

Release from intracellular stores is responsible for calcium signaling with von Willebrand factor in human platelets.

Interaction of von Willebrand factor (VWF) with the platelet promotes hemostasis upon vascular injury. Such interaction raises intracellular free calcium concentration ([Ca2+]i) and induces platelet activation. The platelet [Ca2+]i increase is generally attributed to influx across the plasma membrane. The present study defined the contribution of intracellular calcium stores. Platelet [Ca2+]i was monitored with Fura-PE3. Ristocetin-mediated binding of VWF transiently elevated [Ca2+]i after a lag phase. Studies with 63 healthy donors consistently revealed a VWF-induced platelet [Ca2+]i signal in the absence of extracellular calcium; there was only modest enhancement with extracellular calcium. Blockade of plasma membrane calcium channels did not diminish the signal, whereas depletion or blockade of the intracellular calcium stores abolished it. These findings imply that release from intracellular stores is responsible for the VWF-induced platelet [Ca2+]i increase. Influx across the plasma membrane plays no more than a minor role, probably representing "capacitative entry" to refill the intracellular stores.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗