Biomedical subjects

Peng He

Publications and source records attributed to Peng He.

10 recordsLinked to original sources

PubMed2006

Radical polymerization in biosensing.

This review briefly summarizes recently published work on radical polymerization in biosensor-related applications. Advancements in surface modification aimed at improving sensor biocompatibility and reducing nonspecific background noises are discussed. Direct applications of polymers as one of the key sensing elements in which they are used either as detection probes for the biomolecular binding events or as signal transducers to amplify sensing signals are detailed. Initial applications of radical polymerization reactions in biosensing are evident and appear promising.

Artifacts↗

PubMed2005

In Situ Fourier transform infrared spectroscopic study of the thermal degradation of isotactic poly(propylene).

The conformational change of isotactic poly(propylene) (iPP) during the thermal degradation process has been carefully studied by in situ Fourier transform infrared (FT-IR) spectroscopy. This new method of studying thermal degradation of iPP not only shows the conventional kinetic parameter information of thermal degradation such as the degradation activation energy DeltaE and the degradation factor n, which are in accord with the results of traditional thermogravimetry experiments, but also indicates that many significant molecular structure changes occur during the thermal degradation process that come from some characteristic absorption band changes of in situ FT-IR. A multivariate approach, principal components analysis (PCA), is applied to the analysis of infrared (IR) data, and the results further confirm the multi-step processes of the thermal degradation of iPP. Above all, this is a new application to polymer thermal degradation by in situ FT-IR that connects the intermediate conformational change with final results during thermal degradation.

Algorithms↗

PubMed2005

[Construction of flocculation selective vector and expression of beta-glucosidase gene in Saccharomyces cerevisiae].

Selective markers used in yeast vector for gene manipulation were usually drug resistance or autotrophy. Unfortunately, drug resistance selective marker requires drug sensitive host and most industrial strains were not autotrophy. In this paper, flocculation gene (FLO1) from Saccharomyces cerevisiae ABXL-1D was amplified by PCR, sequenced and cloned to construct an expression vector. The new vector was easy to manipulate and suitable for broad host of yeasts without either autotrophy or drugs. beta-glucosidase gene from Bacillus polymyxa was cloned with the vector and expressed in Saccharomyces cerevisiae. The specific activity of beta-glucosidase of the recombinant yeast cell-free extract was 3.91 u/mg protein. The residue glucose of the recombinant yeast was considerably reduced in mixed fermentation of glucose and cellobiose. It should be favorable for ethanol fermentation when utilize lignocellulosic biomass as raw material.

Bacillus↗

PubMed2004

Purification, characterization, cloning and expression of pyruvate decarboxylase from Torulopsis glabrata IFO005.

In the production of pyruvate and optically active alpha-hydroxy ketones by Torulopsis glabrata, pyruvate decarboxylase (PDC, EC 4.1.1.1) plays an important role in pyruvate metabolism and in catalyzing the biotransformation of aromatic amino acid precursors to alpha-hydroxy ketones. In this paper, we have purified and characterized PDC from T. glabrata IFO005 and cloned the corresponding gene. A simple, rapid and efficient purification protocol was developed that provided PDC with high specific activity. Unlike other yeast or higher plant enzymes, known as homotetramers (alpha(4) or beta(4)) or heterotetramers (alpha(2)beta(2)), two active isoforms of PDC purified from T. glabrata IFO005 were homodimeric proteins with subunits of 58.7 kDa. We isolated the T. glabrata PDC gene encoding 563 amino acid residues and succeeded in overproducing the recombinant PDC protein in Escherichia coli, in which the product amounted to about 10-20% of the total protein of the cell extract. Recombinant PDC from E. coli was purified as a homotetramer. Targeted gene disruption of PDC confirmed that T. glabrata has only one gene of PDC. This PDC gene showed about 80% homology with the genes of other yeasts, and amino acid residues involved in the allosteric site for pyruvate in other yeast PDCs were conserved in T. glabrata PDC. Both native PDC and recombinant PDC were activated by pyruvate and exhibited sigmoidal kinetics similar to those of Saccharomyces cerevisiae and higher plants. They also exhibited the similar catalytic properties: low thermostability, similar pH stability and optimal pH, and complete inhibition by glyoxylate.

Allosteric Site↗

PubMed2004

[Role of telomerase in chrysotile induced malignant transformation of normal human embryonic lung fibroblasts].

OBJECTIVE: To explore the role of telomerase in asbestos dust induced malignant transformation of human embryonic lung fibroblasts in vitro. METHODS: Human telomerase catalytic subunit (hTERT) was transferred into human embryonic lung fibroblasts (HELF). Chrysotile dust at concentration of 2.5 microg/cm(2) was added to HELF transduced with and without hTERT (HELF-T+), respectively, and their transduced foci were separated. Biological characteristics of the cells, telomerase activity, length of telomere and cell growth curve were observed. Colony forming test was performed on soft agar to evaluate the nature of transformation. RESULTS: The hTERT gene was transferred into HELF steadily, and HELF-T+ was established. Malignant transformation occurred in both HELF and HELF-T+ by asbestos stimulation. Asbestos dusts could induce higher rate of transformations in HELF-T+ [(2.08 +/- 1.08)/utensil] than in HELF [(1.08 +/- 0.10)/utensil], P < 0.05. Telomerase activity in both transformed malignant cells and HELF-T+ was higher, as well as the longer length of telomere in them. CONCLUSION: Rate of malignant transformation in cells with more activity of telomerase and longer length of the telomere was higher after stimulation with asbestos, indicating telomerase could play an important role in asbestos induced human cells malignant transformation.

Asbestos, Serpentine↗

PubMed2004

[Role of telomerase in silica induced human cell transformation].

OBJECTIVE: To explore the role of telomerase in silica induced human cell transformation in vitro. METHODS: Human telomerase catalytic subunit (hTERT) was transferred into human embryonic lung fibroblasts (HELF). 160 microg/cm2 silica dusts were added to transform HELF and hTERT transduced HELF (HELF-T+) respectively. The telomerase activity and the length of telomere were determined. The growths of the normal and transformed cells were evaluated. RESULTS: The hTERT gene was steadily transferred into HELF. Silica dusts caused the transformations of both HELF-T+ and HELF. The telomerase activities in transformed cells were higher and the telomere length of transformed cells was longer than those of HELF. CONCLUSION: The changes of telomerase activity and telomere length may play an important role in the silica induced human cells transformation.

Cell Line↗

PubMed2002

[Effects of beech dust extract on lipid peroxidation and expression of ref-1 gene of mouse lung tissue].

In order to explore the effects of beech dust on lipid peroxidation and expression of redox-related gene ref-1, the 2-stage model of mouse lung tumor short-term induction test is used. The mice exposed to the extract beech dust are divided into 3 groups(group of normal lung tissue, group of papillary adenoma and group of lung adenoma) with the mice treated with solvents as control. The extent of homogenate lipid peroxides is determined by measuring the formation of TBARS, and expression of ref-1 measured by immunohistochemistry. The results show that 1. The formation of TBARS of all groups treated with the beech extracts of beech dust is increased compared with the control, and the differences between the groups with adenoma and the control are statistically significant (P < 0.01), while the P value of that of the group of normal lung tissue is less than 0.05. 2. Both the control and the group of normal lung tissue treated with the extracts are Ref-1-negative, strong nuclear Ref-1 immunostaining is found in the group of papillary adenoma, and the cytoplasmic/nuclear expression of Ref-1 is significantly enhanced in the group of lung adenoma and group of mixed adenoma. It is suggested that the extracts of beech dust toxicity is probably related to its altering redox regulation of ref-1 and subsequent disturbance of redox status.

Adenoma↗

PubMed2002

[The model of mouse lung tumor short-term induction test for assaying the carcinogencity induced by extracts of birch wood dust].

OBJECTIVE: To assay the carcinogencity of water and organic extracts of birch wood dust. METHODS: One stage and two stage model of mouse lung tumor by short-term induction test were used. RESULTS: In the one stage experiment, no significant difference of the incidence of mice lung tumors was observed between different dosage groups of water extracts and organic extracts. In the two stage experiment, the tumor incidence and the average number of tumor per mouse in three dosage groups treated with the water extracts(1, 2, 4 g/kg) were 4.08% and 0.04, 8.33% and 0.15, 14.30% and 0.24 respectively with dose increment. There was a significant dose-response relationship between them(P < 0.05), and the tumor incidence and the average number of tumor per mouse in 4 g/kg group were significantly higher than those in the control group and 1 g/kg group and its one stage group(P < 0.05). The tumor incidence and the average number of tumor per mouse induced by organic extracts were higher with increasing dose, but no significant difference among groups was found (P > 0.05). CONCLUSION: Both extracts of birch wood dust may be initiators, and carcinogenic effect of the water extract is stronger than that of the organic extract.

Animals↗

PubMedDate not supplied

Phospholipid-stabilized Au-nanoparticles.

This communication outlines a simple two-step approach of modification of 1 nm diameter Au nanoparticles using an aqueous solution of (1,2-dipalmitoyl-sn-glycero-3-phosphothio-ethanol) phospholipid (PL). Transmission electron microscopy as well as particle size analysis show that, as a result of PL reactions with Au particles, the initial Au nanoparticle size increases to 5 nm. Considering the size of the PL and their ability to form liposomes, 5 nm diameter spheres indicate that the PL bilayer was attached to the surface of Au particles and the PL-Au interactions are facilitated by the presence of thiol functionality. The change of surface electronic properties of PL-stabilized Au particles is manifested by the disappearance of the 217 and 290 nm absorbances due to 5d-6sp transitions in Au, which is likely attributed to the presence of S-H functionalities which increase the free electron density of the particle. As a consequence, two surface plasmons resulting from a collective oscillation of electrons in response to UV excitation disappear.

Drug Stability↗

PubMedDate not supplied

Controlled phospholipid functionalization of single-walled carbon nanotubes.

These studies show that single-walled carbon nanotubes (SWNTs) can be effectively modified using phospholipids. Using a simple surface modification of SWNTs, followed by deposition of 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphoethanolamine (DCPE) phosphipid, results in stable water-dispersible SWNTs with highly uniform thickness.

Biocompatible Materials↗