Biomedical subjects

Peng Li

Publications and source records attributed to Peng Li.

167 records · Page 10Linked to original sources

PubMed2002

[Cloning and analyzing of the cDNA sequence of CHS-A gene of Narcissus].

Chalcone synthase (CHS) is a key enzyme in the biosynthesis of all classes of flavonoids. The production of flower pigment is specifically regulated by the activity of CHS. We cloned the cDNA sequence of CHS-A gene from Narcissus by PCR and analyzed the coding sequence of gene. The result demonstrated that the sequence of the coding region was 1167bp, encoding a protein of 389 amino acid which was more than 80% homology with CHS of the other 8 plants, such as Nicotine abacus and Solana tuberosum.

Acyltransferases↗

PubMed2002

[The advance of tumor development mechanism applying mTR-/- mouse model].

Telomerase is Ribonucleoprotein complex in eukaryocyte, which is composed of telomerase reverse transcriptase(TERT) and telomerase RNA. Telomerase is a special DNA polymerase which can extend the terminal of DNA and maintain the length of telomere. TERT have reverse transcriptase activity. Telomerase activity do not examine in most somatic cell and primary cell, but most tumor cell have strong telomerase activity. It was think that the telomerase has strong relation with tumor occurrences. In this article,the author instruct the correlation of G-strand and P53 in tumor occurrences.

English Abstract↗

PubMed2001

Interleukin (IL)-4 indirectly suppresses IL-2 production by human T lymphocytes via peroxisome proliferator-activated receptor gamma activated by macrophage-derived 12/15-lipoxygenase ligands.

The respective development of either T helper type 1 (Th1) or Th2 cells is believed to be mediated by the effects of cytokines acting directly on Th precursors (Thp). We have generated evidence for an indirect monocyte-dependent immunoregulatory pathway. Recently, interleukin (IL) 4 has been shown to produce "new" potential peroxisome proliferator-activated receptor gamma (PPARgamma) ligands by inducing macrophage 12/15-lipoxygenase (12/15-LO). We have shown previously that the activated PPARgamma is a profound inhibitor of IL-2 transcription in human T lymphocytes. It is hypothetically possible that IL-4 might indirectly affect IL-2 production by Thp cells via macrophage-derived PPARgamma ligands. Using human monocytes and T lymphocytes from same donors, we have found that monocyte 12/15-LO products mediate the indirect inhibitory effect of IL-4 on anti-CD3- or phytohemagglutinin/phorbol 12-myristate 13-acetate-stimulated IL-2 production by T lymphocytes. We further analyzed which major 12/15-LO metabolites contributed to the above inhibition. 13-Hydroxyoctadecadienoic acid (13-HODE), a 12/15-LO product, markedly blocked IL-2 production by human blood T lymphocytes, but not Jurkat T cells. Moreover, the IL-4-conditioned macrophage medium contained a sufficient amount of 13-HODE and anti-13-HODE antibody indeed neutralized the inhibitory effects of the IL-4-conditional medium on T-cell IL-2 production. Using human T lymphocytes and the PPARgamma-transfected Jurkat T cells, we demonstrated the specific inhibition by 13-HODE of the transcription factors NFAT (nuclear factor of activated T cells) and nuclear factor kappaB, the IL-2 promoter reporter, and IL-2 production. However, 15-hydroxytetraenoic acid had little inhibitory effect. The potency of such inhibitory effects correlates well with the capability of the above metabolic lipids to activate PPARgamma. These data provide a mechanism whereby IL-4 may indirectly affect Thp function via PPARgamma activated by macrophage products of the 12/15-LO pathway.

Arachidonate 12-Lipoxygenase↗

PubMed1997

Function of the Hydroxyl Radical in Bleomycin A(5)-induced DNA Degradation.

The production of.OH in the mixture of BLMA(5), Fe(2+) and O(2) has been detected by ESR spectroscopy and the degradation of DNA induced by BLMA(5), in the presence of Fe(2+) and O(2), has been detected by TBA reaction. When Fe(2+) was replaced by Cu(+), Cu(2+) or Fe(3+),.OH was not producted and DNA not degraded.OH scavenger could scavenge.OH effectly but had little effect on the DNA degradation. Reducing agents could scavenge.OH but enhanced the DNA degradation. SOD could scavenge.OH but inactivated SOD showed no effect on.OH. Both SOD and inactivated SOD could inhibit the degradation of DNA.OH reacted more readily with bases than with deoxyribose, while the main injury of DNA induced by BLMA(5) was the destruction of deoxyribose. The results suggest that.OH was generated in the mixture of BLMA(5), Fe(2+) and O(2) but not the key factor which initiated the degradation of DNA. It could be the activated BLMA(5).Fe(2+).O(2) complex that induced the degradation of DNA.

Journal Article↗

PubMed1996

Preparation and Characterization of Superoxide Dismutase Soluble in Organic Solvents.

A glycolipid (2C(12)GE) is synthesized with glutamate, dodecanol and gluconolactone and a glycolipid-coated superoxide dismutase (SOD) is prepared by mixing an aqueous solution of the enzyme with the synthetic 2C(12)GE. The glycolipid-enzyme complex (SOD-2C(12)GE) is insoluble in water but soluble in organic solvents such as ethanol, acetone, glycerin and dioxane. It exhibits a higher activity in some organic solvents such as ethanol than in water and there is an optimum concentration in organic solvent for the catalytic reaction. The SOD-2C(12)GE is more stable against changes in temperature, pH and hydrolysis by protease than the native SOD.

Journal Article↗