Biomedical subjects

D W Jeong

Publications and source records attributed to D W Jeong.

4 recordsLinked to original sources

PubMed2000

Diarylheptanoids from the leaves of Alnus hirsuta Turcz.

Diarylheptanoids, (5S)-1,7-bis-(3,4-dihydroxyphenyl)-5-hydroxyheptane-3-one (1, hirsutanonol), (5S)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-3-one-5-O-beta-D-xylopyranosi de (2, oregonin), (5R)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-beta-D-xylopyranoside (3), and (5R)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-beta-D-glucopyranoside (4) were isolated from the leaves of Alnus hirsuta Turcz. The structures of these compounds were identified based on the spectral and physicochemical data.

Korea↗

PubMed2000

Inhibition of cyclooxygenase-2 expression by diarylheptanoids from the bark of Alnus hirsuta var. sibirica.

Two known diarylheptanoids, oregonin (1), (5S)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-3-one-5-O-beta-D-xylopyranosi de and hirsutanonol (2), (5S)-1,7-bis-(3,4-dihydroxyphenyl)-5-hydroxyheptane-3-one isolated from the bark of Alnus hirsuta var. sibirica, showed significant inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cyclooxygenase-2 (COX-2) expression in immortalized human breast epithelial MCF10A cells.

Cell Line, Transformed↗

PubMed1999

Alteration of the NAD+/NADH ratio in CHO cells by stable transfection with human cytosolic glycerol-3-phosphate dehydrogenase: resistance to oxidative stress.

The intracellular level of the NAD+/NADH ratio plays a vital role in sustaining and coordinating the catabolic reaction of the cell, and reflects the redox state of cytosol. Antioxidants play a role to protect cytosol and membrane from free radicals. This role of antioxidants involves sustaining cell viability and the procedure is thought to be regulated by the equilibrium of the redox state of the cell. However, there is very little known about how the NAD+/NADH level is set and changed. To alter the ratio, human NAD-dependent glycerol-3-phosphate dehydrogenase (cGPDH) cDNA was transfected stably in CHO dhfr- cells. When compared to parental CHO cells, cGPDH activities of the transfected cells were increased 8-12 fold, but the NAD+/NADH ratio was decreased. Specific growth rate of the transfected cells was similar to or slight lower than that of wild type CHO cells. Cell viability of the stable transformants against H2O2 was increased without change of either catalase or glutathione peroxidase activity. However, the increase of cell viability was correlated with the decrease of NAD+/NADH ratio in transfectants. From these results, it is suggested that the overexpression of cGPDH changes the NAD+/NADH ratio toward a decrease, and by this change in the redox state the cell confers more resistance against H2O2.

Animals↗

PubMed1997

Evidence for the complex formation between reverse transcriptase and multicopy single-stranded DNA in retron EC83.

Multicopy single-stranded DNA (msDNA) is produced by reverse transcriptase (RT) and is mutagenic in E. coli. In order to study the interaction between msDNA and RT, an RT open reading frame of retron EC83 was fused with maltose binding protein. The fusion protein, MBP-RT, was active in msDNA synthesis. The msDNA was copurified with MBP-RT by amylose affinity column. When purified msDNA was mixed with MBP-RT, the msDNA formed a complex with the fusion protein. These results show that msDNA is present as a complex with RT in vivo and it is able to form such a complex in vitro. We suggest that RT may compete with MutS protein for binding to msDNA and thereby controls mutagenesis by msDNA.

ATP-Binding Cassette Transporters↗