Biomedical subjects

Fan Zhang

Publications and source records attributed to Fan Zhang.

154 records · Page 9Linked to original sources

PubMed2002

Inhibition of TNF-alpha induced ICAM-1, VCAM-1 and E-selectin expression by selenium.

The initiation of an atherosclerotic lesion involves an endothelial cell pro-inflammatory state that recruits leukocytes and promotes their movement across the endothelium. These processes require endothelial expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial-leukocyte adhesion molecule-1 (E-selectin). Tumor necrosis factor-alpha (TNF-alpha) is a powerful inducer of these adhesion molecules. Selenium status is known to affect the rate of atherosclerosis. These experiments tested whether selenium alters cytokine-induced expression of these adhesion molecules. Human umbilical vein endothelial cells (HUVECs) were pretreated for 24 h with sodium selenite (0-2 microM) and then treated with 0 or 50 U/ml TNF-alpha in the presence of 0-2 microM selenite. ICAM-1, VCAM-1 and E-selectin were detected by ELISA and their mRNAs were evaluated by Northern blots. Selenite significantly inhibited TNF-alpha-induced expression of each adhesion molecule in a dose-dependent manner and reduced the level of the respective mRNAs. Nuclear factor-kappa B (NF-kappa B) is required for transcription of these adhesion molecule genes. Western blot analysis revealed that selenite did not inhibit the translocation of the p65 subunit of NF-kappa B to the nucleus. In conclusion, these data indicate selenium can modulate cytokine-induced expression of ICAM-1, VCAM-1 and E-selectin in HUVECs without interfering with translocation of NF-kappa B.

Analysis of Variance↗

PubMed2002

The effects of protein hydrophobic exposure on the slope of the line in the deltapi vs pi(i) plot.

The deltapi vs pi(i) curve from monolayer surface pressure detection is a powerful method to characterize the membrane insertion. The deltapi vs pi(i) curve is fixed by two parameters, the pi(c) and the slope. The intersected point (pi(c)) of deltapi vs pi(i) curve with abscissa is generally used as a quantitative measure of the membrane insertion ability of a protein. In the current work we demonstrate a correlation between the variation in the slope of the deltapi vs pi(i) curve with protein hydrophobic exposure by performing monolayer experiments on three different proteins, human apolipoprotein H, trichosanthin, and mutant trichosanthin. The value of /slope/ increases gradually following the degree of hydrophobic exposure. These findings suggest that the two parameters, the pi(c) and the slope, will complement each other to interpret the lipid/protein interaction involved in membrane insertion.

Cell Membrane↗

PubMed2002

Induction of cyclooxygenase-2 by tumor promoters in transformed and cytochrome P450 2E1-expressing hepatocytes.

The induction of cyclooxygenase (COX)-2 expression has been implicated as a mechanism for the formation of non-hepatic tumors. Recent investigations have demonstrated COX-2 expression in human hepatocellular carcinomas, but little is known about the regulation of hepatocyte COX-2 expression. Employing the adult, rat hepatocyte line RALA255-10G, the effects of cellular transformation or expression of the alcohol-inducible cytochrome P450 2E1 (CYP2E1) on COX-2 expression were examined. Transformed and non-transformed hepatocytes did not express COX-2 by western and northern blot analysis. The tumor promoters phorbol 12-myristate 13-acetate (PMA) and chenodeoxycholic acid (CD) induced COX-2 protein expression in transformed, but not non-transformed cells. CYP2E1-expressing cells lacked constitutive COX-2 expression, and PMA but not CD induced COX-2 in these cells. PMA-treated transformed and CYP2E1-expressing cells expressed functional COX-2 as demonstrated by marked inductions in prostaglandin E(2) synthesis. PMA-induced COX-2 expression in both transformed and CYP2E1-expressing cells resulted from an induction in COX-2 mRNA, and was dependent on extracellular signal-regulated kinase, p38 mitogen-activated protein kinase and phosphatidylinositol 3-kinase. The differential induction of COX-2 by PMA in transformed and non-transformed cells could not be explained by differences in NF-kappaB or C/EBPalpha activation. PMA did not induce COX-2 transcriptional activity as determined by transient transfections with a luciferase reporter gene driven by the COX-2 promoter. The data demonstrate that cellular transformation and CYP2E1 expression fail to lead to the induction of COX-2 expression in hepatocytes. However, these conditions do render hepatocytes susceptible to COX-2 induction from tumor promoters by post-transcriptional mechanisms.

Animals↗

PubMed2002

A minimal chimera of human cyclin T1 and tat binds TAR and activates human immunodeficiency virus transcription in murine cells.

The transcriptional elongation of human immunodeficiency virus type 1 (HIV-1) is mediated by the virally encoded transactivator Tat and its cellular cofactor, positive transcription elongation factor b (P-TEFb). The human cyclin T1 (hCycT1) subunit of P-TEFb forms a stable complex with Tat and the transactivation response element (TAR) RNA located at the 5' end of all viral transcripts. Previous studies have demonstrated that hCycT1 binds Tat in a Zn(2+)-dependent manner via the cysteine at position 261, which is a tyrosine in murine cyclin T1. In the present study, we mutated all other cysteines and histidines that could be involved in this Zn(2+)-dependent interaction. Because all of these mutant proteins except hCycT1(C261Y) activated viral transcription in murine cells, no other cysteine or histidine in hCycT1 is responsible for this interaction. Next, we fused the N-terminal 280 residues in hCycT1 with Tat. Not only the full-length chimera but also the mutant hCycT1 with an N-terminal deletion to position 249, which retained the Tat-TAR recognition motif, activated HIV-1 transcription in murine cells. This minimal hybrid mutant hCycT1-Tat protein bound TAR RNA as well as human and murine P-TEFb in vitro. We conclude that this minimal chimera not only reproduces the high-affinity binding among P-TEFb, Tat, and TAR but also will be invaluable for determining the three-dimensional structure of this RNA-protein complex.

3T3 Cells↗

PubMed2002

[Anti-apoptosis gene survivin promotes cell growth and transformation].

OBJECTIVE: To investigate the role and molecular mechanism of surviving, an anti-apoptosis gene, in cell growth and transformation. METHODS: Coding sequence of surviving was amplified from Daudi cell mRNA by RT-PCR and then cloned into prokaryotic and eukaryotic vectors. The vectors with surviving were transfected into BL21 cells of Escherichia coli and human embryonic kidney 293 cells. The cells were cultured. Protein was extracted from the cells and examined by gel electrophoresis. Suspension of 293 cells was cultured and the number of cells was counted every other day, thus a growth curve was drawn. Another suspension of 293 cells was cultured in soft agar to observe the number of colonies. Cells transfected with plasmids void of surviving were used as controls. RESULTS: The anti-apoptosis gene surviving was well expressed in BL21 cells and 293 cells. The growth curve showed that the proliferation rate of 293 cells was slightly faster than that of control cells, however, without significant difference. Soft agar assay showed that the colonies formed by surviving-transfected 293 cells were of greater size and with greater number. Western blotting showed overexpression of cyclin D1 and c-myc, two important cancer proteins, in cells transfected with surviving. CONCLUSION: The anti-apoptosis gene surviving promotes cell transformation. These effects may depend on the functions of cyclin D1 and c-myc.

Apoptosis↗

PubMed2002

Arachidonate CYP hydroxylases of kidney contribute to formation of hypertension and maintenance of blood pressure.

AIM: To investigate the relationship of kidney-specific expression of cytochrome P-450 (CYP) 4A1 and the blood pressure. METHODS: The specific sense and antisense CYP4A1 cDNA was administered respectively with the help of eukaryotic expression vector pcDNA3.1 to the Sprague-Dawley (SD) rats via sublingual vein (2 mg/kg). The systolic blood pressure of rats was assessed by the tail- cuff method, and the relative tissue expression of CYP4A1 was analyzed by Western blot and Northern blot at RNA and protein levels in the brain, heart, lung, liver, and kidney of control, sense, and anti-sense CYP4A1 cDNA-treated rats. RESULTS: Two weeks after the injection of the sense and antisense CYP4A1 cDNA recombinants respectively, the mean systolic pressure of the transgenic rats increased by 1.8 kPa +/- 0.3 kPa (13.2 mmHg +/- 2.5 mmHg) or decreased by 1.7 kPa +/- 0.3 kPa (13.0 mmHg +/- 2.2 mmHg) compared with control. At the levels of transcription and translation, the Northern and Western blots all demonstrated that CYP4A1 preferentially overexpressed in the kidney. CONCLUSION: The administration of sense and antisense CYP4A1 cDNA induced hypertension and hypotension, respectively, which indicated that renal arachidonate hydroxylase contributed to the formation of hypertension and maintenance of blood pressure in normotensive rats.

Animals↗

PubMed2002

A genetic algorithm based stochastic programming model for air quality management.

This paper presents a model that can aid planners in defining the total allowable pollutant discharge in the planning region, accounting for the dynamic and stochastic character of meteorological conditions. This is accomplished by integrating Monte Carlo simulation and using genetic algorithm to solve the model. The model is demonstrated by using a realistic air urban-scale SO2 control problem in the Yuxi City of China. To evaluate effectiveness of the model, results of the approach are shown to compare with those of the linear deterministic procedures. This paper also provides a valuable insight into how air quality targets should be made when the air pollutant will not threat the residents' health. Finally, a discussion of the areas for further research are briefly delineated.

Air Pollutants↗

PubMed2002

Alterations of the hSNF5/INI1 gene in central nervous system atypical teratoid/rhabdoid tumors and renal and extrarenal rhabdoid tumors.

Germ-line and acquired mutations of the hSNF5/INI1 tumor suppressor gene have been reported in central nervous system (CNS), renal, and soft-tissue rhabdoid tumors. The present study was designed to compare the types of INI1 alterations among tumors from diverse anatomical sites and identify mutation hot spots. Fluorescence in situ hybridization and PCR-based microsatellite, heteroduplex, and sequence analysis were used to characterize chromosome 22 deletions and INI1 mutations among 100 primary rhabdoid tumors. Deletions and/or mutations of INI1 were detected in 75 patients, including 42 children with atypical teratoid/rhabdoid tumors of the brain or spinal cord and 6 children with a brain and a renal or soft-tissue tumor. Nineteen tumors arose in the kidney (in one child, bilaterally) and eight tumors were extra-renal. Homozygous deletions detected by fluorescence in situ hybridization were most often seen in CNS and extra-renal rhabdoid tumors, whereas truncating mutations were detected in a high percentage of CNS and kidney tumors. The highest frequencies of INI1 mutations for kidney tumors were seen in exons 2, 6, and 7, compared with exons 5 and 9 for CNS tumors. Two potential hot-spot mutations for CNS atypical teratoid/rhabdoid tumors were noted, including a C-to-T transition in codon 201 in exon 5 and a cytosine deletion in exon 9. Germ-line mutations were noted in 10 children, including 4 patients with two primary tumors. The majority of rhabdoid tumors from all sites contained deletions and/or mutations of the INI1 gene. Specific mutations were nonrandomly associated with anatomical site.

Brain Neoplasms↗

PubMed2002

[Spirometrically controlled quantitative CT for detection of pulmonary function in silica-exposed workers].

OBJECTIVE: To evaluate the diagnostic value of spirometrically controlled quantitative CT in silica-exposed workers. METHODS: Whole lung spiral scans at 50% vital capacity (VC) and image with high resolution CT(HRCT) at 10% VC and 90% VC level and 5 cm above/below carina were performed in 62 silica-exposed workers and 54 healthy adults. Automatic evaluation software, Pulmo, was used to evaluate the quantitative parameters and compared with clinical pulmonary function tests. RESULTS: 9 workers with emphysema were detected by CT scans from 62 silica-exposed workers. The quantitative parameters of 10% VC and 90% VC were significantly different between the silica-exposed workers and the controls (P < 0.05). With the increasing of length of exposure to silica dust, the difference showed a ladder-like rising. CONCLUSION: Spirometrically controlled quantitative CT is a sensitive, accurate and objective method. It is superior to conventional CT and pulmonary function tests for the early detection in silica-exposed workers, espicially for detecting early stage of small airway disease.

Humans↗

PubMed1996

Purification of Protein Disulfide-isomerase from Human Liver and Preparation of Its Antiserum.

Protein disulfide-isomerase has been isolated from human liver. The preparative procedure involved heat treatment, (NH(4))(2)SO(4) precipitation, CM-Sephadex C50 and DEAE-fast flow chromatography. The enzyme was homogenous and had a molecular mass of 60 kD or 120 kD as determined by sodium dodecy1 sulphate electro-phoresis and gel filtration respectively, indicating that the enzyme was a 120 kD dimmer with a subunit with molecular mass of 60 kD. The enzyme activity was as high as 830 U/g.protein as measured by the reactivation of "scrambled" ribonuclease. The antiserum of high titer was prepared by immunizing New Zealand rabbit with a mixture of the protein disulfide-isomerase and adjuvant.

Journal Article↗