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Biomedical subjects

Ying Mu

Publications and source records attributed to Ying Mu.

26 records · Page 2Linked to original sources
PubMed2003

A novel sandwich immunosensing method for measuring cardiac troponin I in sera.

Common methods for monitoring human cardiac troponin I (cTn I) are based on using antibodies against cTn I labeled with horseradish peroxidase, radioactive isotopes, or other labels. In this study, a novel label-free sandwich immunosensing method for measuring cTn I was developed. Three monoclonal antibodies (mAbs 9F5, 2F11, and 8C12) against human cTn I were generated by the commonly used hybridoma technique and characterized by a surface plasmon resonance (SPR) biosensor. An optimal pair of mAbs for measuring human cTn I was selected, as both mAbs have high affinities for cTn I and do not compete against each other for cTn I binding. An optical immunosensor for measuring cTn I in sera based on SPR was developed by using avidin as an intermediate layer and biotinylated-2F11 as the capturing antibody. Two detection methods for cTn I with the immunosensor were performed: (1) the direct detection of cTn I with a detection range of 2.5 to 40 microg/L and (2) the sandwich immunosensing method. In the sandwich assay mode, the second antibody 9F5 biologically amplified the sensor response. As a result, the sandwich assay showed a sensitivity of 0.25 microg/L and a detection range of 0.5 to 20 microg/L with within-run variation of 4.9 to 6.7% and between-run variation of 5.2 to 8.4%. This method has greatly enhanced the sensitivity for detection compared to that previously reported in the literatures.

Antibodies, Monoclonal↗
PubMed2003

Protection of epidermal cells against UVB injury by the antioxidant selenium-containing single-chain Fv catalytic antibody.

The antioxidant effect of selenium-containing single-chain Fv catalytic antibody (Se-scFv2F3), a new mimic of glutathione peroxidase, was confirmed using a model system in which cultured rat skin epidermal cells were injured by ultraviolet B (UVB). The cell damage was characterized in terms of lipid peroxidation of the cells, cell viability, and cell membrane integrity. The injury effects of UVB and protection effects of Se-scFv2F3 on the cells were studied using the model system. UVB can damage the cells severely. Upon precultivation of the cells with 0.4U/ml Se-scFv2F3, however, the damage was significantly reduced as shown by the increase in cell viability, the decrease in the malondialdehyde and hydrogen peroxide levels, and the normalization of lactate dehydrogenase activity. In addition, a novel finding that Se-scFv2F3 can stimulate cultured epidermal cells to proliferate under certain conditions was observed.

Animals↗
PubMed2003

UV-B induced keratinocyte apoptosis is blocked by 2-selenium-bridged beta-cyclodextrin, a GPX mimic.

Cell proliferation and cell death of keratinocytes are tightly regulated to ensure epidermal homeostasis. UV-B induces keratinocyte apoptosis. UV-B also induces lipid peroxidation of keratinocytes to increase their amount of malondialdehyde (MDA). These phenomena can be explained by the production of reactive oxygen species (ROS) induced by UV-B radiation. We synthesized 2-selenium-bridged beta-cyclodextrin (2-SeCD) to imitate glutathione peroxidase (GPX), an important antioxidant and established a damage system, in which keratinocytes can be damaged by Ultraviolet B (UV-B) radiation. Using this damage system we studied 2-SeCD protection of keratinocytes against injury induced by UV-B. Experimental results showed that 2-SeCD could protect keratinocytes from apoptosis. Moreover, 2-SeCD inhibits lipid peroxidation of keratinocytes and scavenges ROS. 2-SeCD inhibits the UV-B induced apoptotic signal transduction. This antiapoptotic mechanism may be partly related to the elimination of hydrogen peroxide.

Apoptosis↗
PubMed2003

Towards more efficient glutathione peroxidase mimics: substrate recognition and catalytic group assembly.

Glutathione peroxidase (GPX) is a well-known selenoenzyme that functions as an antioxidant and catalyzes the reduction of harmful peroxide by glutathione and protects cells against oxidative damage. Because many diseases are related to oxidative stress, GPX is an ancient foe of many diseases. Antioxidants are very useful for biological bodies, and considerable effort has been spent to find compounds that could imitate the properties of GPX. This paper reviews GPX mimics developed so far and describes a new, more effective strategy for fabricating them. Although many GPX mimics have been made, they possess serious disadvantages: low activity, low solubility in water, and, in some cases, toxicity. In order to overcome these drawbacks, we have proposed a new strategy of imitating GPX. First, a receptor with a substrate binding site is generated. Next, a catalytic group is incorporated into the receptor near the substrate binding site, allowing the catalytic group access to the functional group of the substrate. Finally, a highly efficient enzyme mimic is obtained. Using this strategy, we successfully fabricated GPX mimics that use antibodies, cyclodextrins, some enzymes and proteins as receptors and chemical modification to incorporate the catalytic group, selenocysteine (Sec). The general principle of combining a functional group involved in catalysis with a specific binding site for the substrate is an approach that could be applied to the generation of other efficient semisynthetic biocatalysts. We describe the antioxidant activities of these GPX mimics and the reasons of their being promising candidates for medicinal applications.

Animals↗
PubMed2002

A novel cyclodextrin-derived tellurium compound with glutathione peroxidase activity.

A novel dicyclodextrinyl ditelluride (2-TeCD) compound was devised as a functional mimic of the glutathione peroxidase (GPX) enzymes that normally remove hydroperoxides from the cell. The GPX activity of the mimic was found to be 46.7 U microM(-1), which is 46 times as active as Ebselen, a well-known GPX mimic. A detailed steady-state kinetic study was undertaken to probe the reason for the high catalytic efficiency of 2-TeCD. This high efficiency can be explained based on both the binding of the substrate to the cyclodextrin and the catalytic mechanism of 2-TeCD, which is different from that of diselenide compounds. 2-TeCD exhibits good water solubility and is chemically and biologically stable. The biological effect of 2-TeCD was evaluated by its ability to protect mitochondria from oxidative damage. 2-TeCD exhibited excellent antioxidant capacity in comparison with Ebselen.

Animals↗
PubMed2002

[Studies on the optimal expression condition, purification and its characterization of ScFv-2F3].

The expression vectors of the gene encoding ScFv-2F3 were transformed into E. coli BL21(DE3). Clones of higher expression were first selected, then were grown in the presence of IPTG at 37 degrees C to induce its expression. The culture conditions were carefully optimized. It was found that optimal conditions were as follows: the induction was started as OD590 reached to 1.0-1.8; the concentration of IPTG was 0.3-0.5 mmol/L and induction time is 7 h. The yield of ScFv-2F3 expressed in the selected clones is about 20% of the total proteins. The optimal culture conditions were successfully applied to fermenter of 50 L. The conditions of washing the inclusion bodies were also optimized. A two-step method was used to renature the inclusion body. The expression product of interest and its biological activities were characterized with Western blotting and ELISA. A novel selenium-containing single-chain abzyme with GPX activity was prepared.

Antibodies, Catalytic↗
PubMed2002

The progress in mechanism of selenoprotein biosynthesis.

As the twenty-first amino acid, selenocysteine can be co-translationally incorporated into the polypeptide chain at UGA codon in the coding region of selenoprotein mRNA. The incorporation of selenocysteine needs a cis-acting element SECIS and four gene products: SelA, SelB, SelC and SelD. The position of SECIS in the mRNA of prokaryote and its structural features are greatly different from that of eukaryote. The researchers have made exploration in selenoprotein engineering by virtue of the mechanism of selenocysteine incorporation in Escherichia coli.

Base Sequence↗