Biomedical subjects

K Liu

Publications and source records attributed to K Liu.

599 records · Page 34Linked to original sources

PubMedDate not supplied

Anti-estrogenic activities of indole-3-carbinol in cervical cells: implication for prevention of cervical cancer.

BACKGROUND: Cervical cancer constitutes the second most common cancer in women. Estrogen promotes development of cervical cancer in cells infected with high risk human papillomaviruses (HPVs). We asked whether the phytochemical indole-3-carbinol (I3C) has anti-estrogenic activities in cervical cells with the goal of preventing cancer in HPV infected cells. MATERIALS AND METHODS: Using the cervical cancer cell line CaSki, we evaluated expression of HPV and cytochrome p450 (CYP) enzymes by Northern, RNase protection or quantitative RT-PCR. I3C binding to estrogen receptor was measured by competition with estradiol. Estrogen metabolites were measured by gas chromarography-mass spectrometry (GC-MS). RESULTS: Estradiol increased expression of HPV oncogenes whereas I3C and the estrogen metabolite 2-hydroxyestrone (2-OHE) abrogated the estrogen-increased expression of HPV oncogenes. Both I3C and 2-OHE competed with estradiol for estrogen receptor binding. I3C enhanced gene expression of CYP enzymes responsible for 2-hydroxylation of estrogen, and induced the formation of 2-OHE. CONCLUSION: I3C has anti-estrogenic activities which should prevent cancer in cervical cells.

Anticarcinogenic Agents↗

PubMedDate not supplied

Enantioselective hydrolysis of lorazepam 3-acetate by esterases in human and rat liver microsomes and rat brain S9 fraction.

Rates of hydrolysis of racemic and enantiomeric lorazepam 3-acetates (LZA) by esterases in human and rat liver microsomes and rat brain S9 fraction were compared. LZA and its hydrolysis product were analyzed by chiral stationary phase HPLC. When rac-LZA was the substrate, the (R)-LZA was hydrolyzed 2.7-fold and 6.8-fold faster than the (S)-LZA by esterases in rat and human liver microsomes, respectively. In contrast, esterases in rat brain S9 fraction were enantioselective toward the (S)-LZA. The specific activities (nmol of LZA hydrolyzed/mg protein/min) of liver microsomes in the hydrolysis of enantiomerically pure (R)-LZA were approximately 210 (rat) and 1330 (human), and in the hydrolysis of enantiomerically pure (S)-LZA were 25 (rat) and 8 (human). The specific activities of rat brain S9 fraction in the hydrolysis of enantiomerically pure (R)-LZA and (S)-LZA were approximately 3 and 6 nmol/mg protein/min, respectively. Results also indicated an enantiomeric interaction in the hydrolysis of rac-LZA; the presence of (R)-LZA stimulated the hydrolysis of (S)-LZA by all esterase preparations, whereas the presence of (S)-LZA stimulated the hydrolysis of (R)-LZA in rat brain S9 fraction and inhibited the hydrolysis of (R)-LZA in rat and human liver microsomes.

Animals↗

PubMedDate not supplied

Recruiting young adults in an urban setting: the Chicago CARDIA experience.

The recruitment goal of Chicago Coronary Artery Risk Development in Young Adults (CARDIA) was 1,100 randomly selected young adults, in equal proportions for men and women, blacks and whites, two age groups, and two education groups. CARDIA is an ongoing multicenter study of the health and lifestyles of young adults designed to trace the development of risk factors for coronary heart disease over time. Participants completed a four-and-one-half hour exam and agreed to return two years later. In Chicago CARDIA, one of the four centers in the national collaborative study, random digit dialing of computer-generated telephone lists was the initial recruitment technique. Initial recruitment efforts resulted in too few low-socioeconomic status (SES) white participants and too few blacks. In response the sampling procedure was modified to focus on census tracts with a high density of blacks, more low-SES whites, and convenient public transportation. By being flexible, Chicago CARDIA improved recruitment in certain hard-to-fill cells and achieved the overall goals: 1,109 participants, 50% black and 50% white, near equal proportions by sex and age, and close to the recommended 40%/60% spread on education. The Chicago experience should benefit others conducting research in an urban setting.

Adult↗

PubMedDate not supplied

Interferons upregulate the expression of laminin and its receptor LBP-32 in cultured cells.

We have studied the effects of interferon (IFNs) alpha and gamma on the regulation and expression of laminin (LMN) and a 32 kD laminin binding protein (LPB-32) in cultured human umbilical vein endothelial cells (HUVEC) and human foreskin fibroblast (FS-4) cells. We show that IFNs increased immunofluorescent staining for LMN and LPB-32. In HUVEC, B1 and B2 chain immunoprecipitated proteins were enhanced in the extracellular (released) fraction by IFN-alpha, but were decreased by IFN-gamma. In intracellular (cell-associated) fractions, both B chains were increased, especially by IFN-gamma. In situ hybridization of FS-4 cells demonstrated increased B2 chain mRNA in the presence of IFNs. Reverse transcription-polymerase chain reaction amplification (RT-PCR) indicated that B1 chain mRNA was increased by both IFNs in HUVEC, and by IFN-gamma in FS-4. The increased synthesis of LMN and LBP-32 may be important in promoting wound healing and angiogenesis.

Cells, Cultured↗

PubMedDate not supplied

Vanadium (IV) formation in the reduction of vanadate by glutathione reductase/NADPH and the role of molecular oxygen.

Experimental evidence documenting the formation of a relatively stable V(IV) species appears to be important with regard to the biochemical mechanism of reduction of vanadate by enzymatic systems. The present study demonstrates that a mixture of vanadate and glutathione reductase/nicotinamide-adenine-dinucleotide phosphate (NADPH), in phosphate (pH 7.2) buffer generates V(IV) under ambient conditions. Once formed, V(IV) does not rapidly autoxidize so as to defy detection by electron spin resonance (ESR) spectroscopy. The aerobic environment was guaranteed by preparing reaction mixtures in well stirred, wide mouth, standard test tubes in air over a period of 50 minutes, and by making ESR measurements in nuclear magnetic resonance (NMR) sample tubes as well as oxygen-permeable Teflon tubes. The V(IV) ESR signal intensity was found to increase linearly with time elapsed after reaction initiation. The linear growth of the V(IV) species also shows that this species is fairly stable, over a period of at least 50 minutes. Similar V(IV) stability data were obtained from VOSO4, a model compound as a source of V(IV). The results obtained in the present study demonstrated that V(IV) can be generated in the reduction of V(IV) by glutathione reductase in the presence of NADPH under aerobic condition.

Electron Spin Resonance Spectroscopy↗