Biomedical subjects

Fang Li

Publications and source records attributed to Fang Li.

At least 73 records · Page 4Linked to original sources

PubMed2005

Clinical diagnosis and treatment of nonfunctioning pheochromocytomas in 14 patients.

OBJECTIVE: To analyze the clinical characteristics of nonfunctioning pheochromocytoma, and to evaluate the efficacy of 131I-metaiodobenzylguanidine (MIBG) scan in the diagnosis and perioperative treatment of nonfunctioning pheochromocytoma. METHODS: The clinical data of 14 patients with nonfunctioning pheochromocytoma were analyzed retrospectively. Plasma free corticoid, renin, aldosterone, and urine catecholamines levels were estimated. B-mode ultrasonography, computed tomography scan, thoracic X-ray and 131I-MIBG were used. RESULTS: All patients with nonfunctioning pheochromocytoma had no hypertension and the tumors were found incidentally. The 24 hours urine catecholamines levels in 80% (8/10) patients were normal. The positive rate of 131-MIBG was 80% (8/10) and the specificity was 100%. All patients underwent surgical operation of tumor resection. No preoperative volume expansion was given to all patients. All tumors were resected completely, and no death accident happened. There was no recurrence and metastasis after operation by long-term follow-up. CONCLUSION: 131I-MIBG scan is the first choice technique for the diagnosis of nonfunctioning pheochromocytoma. Blood volume expansion is unnecessary before resection of pheochromocytoma.

3-Iodobenzylguanidine↗

PubMed2005

[Clinical significance of adenosine 99mTc-MIBI myocardial perfusion single photon emission computed tomography for patients in percutaneous coronary intervention].

OBJECTIVE: To analyze the clinical significance of adenosine (99m)Tc-MIBI myocardial perfusion single photon emission computed tomography (SPECT) in patients with coronary artery disease (CAD) for percutaneous coronary intervention (PCI). METHODS: Coronary angiography and adenosine (99m)Tc-MIBI myocardial perfusion SPECT were performed for all patients. Adenosine myocardial perfusion was performed after PCI. Adenosine was infused intravenously at a rate of 140 microg.kg(-1).min(-1) for 6 minutes, and 925MBq (99m)Tc-MIBI was injected intravenously at 3 minutes after adenosine infusion. SPECT myocardial imaging acquisition was obtained in 1.5 hours after adenosine infusion. If the result was abnormal, rest (99m)Tc-MIBI myocardial perfusion SPECT would be performed next day. There were 17 segments of left ventricle, and four degrees of myocardial perfusion. RESULTS: There were 63 cases (63 +/- 10 years old) with CAD, in which 40 patients got PCI. Twenty eight cases after PCI. CONCLUSION: Adenosine myocardial perfusion imaging will be useful in detecting regional myocardial perfusion abnormalities for patients with PCI.

Adenosine↗

PubMed2004

Dissecting requirements for auto-inhibition of actin nucleation by the formin, mDia1.

The mammalian formin, mDia1, is an actin nucleation factor. Experiments in cells and in vitro show that the N-terminal region potently inhibits nucleation by the formin homology 2 (FH2) domain-containing C terminus and that RhoA binding to the N terminus partially relieves this inhibition. Cellular experiments suggest that potent inhibition depends upon the presence of the diaphanous auto-regulatory domain (DAD) C-terminal to FH2. In this study, we examine in detail the N-terminal and C-terminal regions required for this inhibition and for RhoA relief. Limited proteolysis of an N-terminal construct from residues 1-548 identifies two stable truncations: 129-548 and 129-369. Analytical ultracentrifugation suggests that 1-548 and 129-548 are dimers, whereas 129-369 is monomeric. All three N-terminal constructs inhibit nucleation by the full C terminus. Although inhibition by 1-548 is partially relieved by RhoA, inhibition by 129-548 or 129-369 is RhoA-resistant. At the C terminus, DAD deletion does not affect nucleation but decreases inhibitory potency of 1-548 by 20,000-fold. Synthetic DAD peptide binds both 1-548 and 129-548 with similar affinity and partially relieves nucleation inhibition. C-terminal constructs are stable dimers. Our conclusions are as follows: 1) DAD is an affinity-enhancing motif for auto-inhibition; 2) an N-terminal domain spanning residues 129-369 (called DID for diaphanous inhibitory domain) is sufficient for auto-inhibition; 3) a dimerization region C-terminal to DID increases the inhibitory ability of DID; and 4) DID alone is not sufficient for RhoA relief of auto-inhibition, suggesting that sequences N-terminal to DID are important to RhoA binding. An additional finding is that FH2 domain-containing constructs of mDia1 and mDia2 lose >75% nucleation activity upon freeze-thaw.

Actins↗

PubMed2004

Enhancement of hypoxia-induced tumor cell death in vitro and radiation therapy in vivo by use of small interfering RNA targeted to hypoxia-inducible factor-1alpha.

Hypoxia-inducible factor-1alpha (HIF-1alpha) is an important transcriptional factor that is activated when mammalian cells experience hypoxia, a tumor microenvironmental condition that plays pivotal roles in tumor progression and treatment. In this study, we examined the idea of down-regulating HIF-1alpha in tumor cells for therapeutic gain. We show that the expression levels of HIF-1alpha can be significantly attenuated by use of the recently established small interfering RNA technology in combination with adenovirus-mediated gene transfer. Down-regulation of the HIF-1alpha protein enhanced hypoxia-mediated tumor cell apoptosis in vitro. Subcutaneous tumor growth was also prevented from cells with attenuated HIF-1alpha expression. In addition, intratumoral injection of adenovirus encoding the HIF-1alpha-targeted small interfering RNA had a small but significant effect on tumor growth when combined with ionizing radiation. Therefore, our results provide proof of HIF-1alpha as an effective target for anticancer therapy. They also suggest that an adenovirus-based small interfering RNA gene transfer approach may be a potentially effective adjuvant strategy for cancer treatment.

Apoptosis↗

PubMed2004

Angiotensin II-induced Akt activation through the epidermal growth factor receptor in vascular smooth muscle cells is mediated by phospholipid metabolites derived by activation of phospholipase D.

Angiotensin II (Ang II) activates cytosolic Ca(2+)-dependent phospholipase A(2) (cPLA(2)), phospholipase D (PLD), p38 mitogen-activated protein kinase (MAPK), epidermal growth factor receptor (EGFR) and Akt in vascular smooth muscle cells (VSMC). This study was conducted to investigate the relationship between Akt activation by Ang II and other signaling molecules in rat VSMC. Ang II-induced Akt phosphorylation was significantly reduced by the PLD inhibitor 1-butanol, but not by its inactive analog 2-butanol, and by brefeldin A, an inhibitor of the PLD cofactor ADP-ribosylation factor, and in cells infected with retrovirus containing PLD(2) siRNA or transfected with PLD(2) antisense but not control LacZ or sense oligonucleotide. Diacylglycerol kinase inhibitor II diminished Ang II-induced and diC8-phosphatidic acid (PA)-increased Akt phosphorylation, suggesting that PLD-dependent Akt activation is mediated by PA. Ang II-induced EGFR phosphorylation was inhibited by 1-butanol and PLD(2) siRNA and also by cPLA(2) siRNA. In addition, the inhibitor of arachidonic acid (AA) metabolism 5,8,11,14-eicosatetraynoic acid (ETYA) reduced both Ang II- and AA-induced EGFR transactivation. Furthermore, ETYA, cPLA(2) antisense, and cPLA(2) siRNA attenuated Ang II-elicited PLD activation. p38 MAPK inhibitor SB202190 [4-(4-flurophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole] reduced PLD activity and EGFR and Akt phosphorylation elicited by Ang II. Pyrrolidine-1, a cPLA(2) inhibitor, and cPLA(2) siRNA decreased p38 MAPK activity. These data indicate that Ang II-stimulated Akt activity is mediated by cPLA(2)-dependent, p38 MAPK regulated PLD(2) activation and EGFR transactivation. We propose the following scheme of the sequence of events leading to activation of Akt in VSMC by Ang II: Ang II-->cPLA(2)-->AA-->p38 MAPK-->PLD(2)-->PA-->EGFR-->Akt.

Angiotensin II↗

PubMed2004

Polymorphisms in the DNA repair gene XPD and susceptibility to esophageal squamous cell carcinoma.

Polymorphisms of the nucleotide excision repair gene XPD are candidates for influencing cancer susceptibility. To determine the effect of XPD genetic polymorphisms on the risk of esophageal squamous cell carcinoma (ESCC) and its interaction with carcinogen exposure, XPD polymorphisms at codon 312 (Asp-->Asn) and codon 751 (Lys-->Gln) were determined in 135 ESCC patients and 152 normal controls. Polymorphism at codon 312 made no contribution to genetic risk for ESCC. Our results showed that there was a significant difference between frequencies for XPD 751 Gln/Gln genotype in ESCC patients (8.9%) and normal cases (1.3%), and that Gln/Gln genotype was associated with an increased risk of ESCC (odds ratio [OR] = 6.71; 95% confidence interval [CI]: 1.90-23.73). The results of the logistic regression model showed that XPD 751 Gln/Gln genotype and drinking were candidates for influencing the risk of ESCC. Among smokers, the risk of ESCC in XPD 751 Gln/Gln genotype increased 8-fold than that XPD 751 Lys/Lys genotype (OR = 8.42, 95% CI: 1.02-69.58). The results indicated that XPD 751 Gln/Gln genotype may be contributing factors in the risk of ESCC and may modify risk attributable to environmental exposures.

Aged↗

PubMed2004

Ultrasensitive detection of protein using an aptamer-based exonuclease protection assay.

Currently, methods for protein detection are not as sensitive and specific as methods for detection of specific nucleic acid sequences. Here, we present an analogous technique for detection of proteins using aptamers as ligands for target binding. We have named this method the aptamer-based exonuclease protection assay. We applied a special oligonucleotide probe containing a thrombin aptamer, which has the capacity to recognize thrombin with high affinity and specificity. The aptamer probe is a 22-base-long single-strand oligonucleotide with the thrombin aptamer sequence at the 3'-terminus and 7 additional nucleotides at the 5'-terminus, which is able to bind thrombin with high affinity and specificity. In the exonuclease protection assay, thrombin binds the aptamer and thereby protects it from degradation by exonuclease I, whereas any unbound aptamer probe is degraded by exonuclease I. Subsequently, the aptamer probes that were protected from exonuclease I by thrombin act as linkers to join two free connectors, which contain sequences matching the probe. The joined products, which reflect the identity and amount of the target protein, are amplified by PCR. The exonuclease protection assay is extremely sensitive, since it is based on PCR amplification. This method can detect as few as several hundred molecules of target protein without using washes or separations. In addition, this new method for protein detection is simple and inherits all the advantages of aptamers. The mechanism, moreover, may be generalized and used for other forms of protein analysis.

Aptamers, Nucleotide↗

PubMed2004

Telomerase activity and expression of telomerase genes in squamous dysplasia and squamous cell carcinoma of the esophagus.

BACKGROUND: Telomerase maintains telomere length and is considered to be necessary for the indefinite proliferation of human cells. Activation of telomerase plays a key role in the malignant transformation process. The aim of this study was to study the regulation of telomerase, and to explore the possibility of telomerase as a biomarker in squamous carcinogenesis of the esophagus. METHODS: Twenty-nine esophageal squamous cell carcinomas (ESCC) and its corresponding adjacent normal tissues, and 47 epithelial squamous dysplasia tissues were analyzed by the reverse transcriptase-polymerase chain reaction (RT-PCR) technique for the mRNA expression of three major telomerase subunits: human telomerase RNA (hTR), telomerase protein component 1 (TP1), and human telomerase reverse transcriptase (hTERT) and by telomeric repeat amplification protocol assay (TRAP) for telomerase activity. RESULTS: For the expression of hTR and TP1 mRNA, there were no significant differences among ESCC, dysplasia and normal tissues (P > 0.05). In contrast, hTERT mRNA expression was detected in 28 of 29 ESCC (96.6%), in 23 of 47 dysplasia (48.9%), and only in two of 29 normal tissues (7.5%). Telomerase activity was positive in 25 of 29 ESCC (86.2%), in 21 of 47 (44.7%) epithelial dysplasia tissues, and in none of normal tissue. All together, 95 of 105 cases (90.48%) were concordant for both results, i.e., telomerase activity positive and hTERT positive or telomerase activity negative and hTERT negative tissues, and telomerase activity correlated with hTERT mRNA expression (P < 0.001). CONCLUSIONS: Higher telomerase activity and hTERT mRNA expression were shown during an early stage in the esophageal carcinogenesis. Activation of telomerase activity was strongly correlated with hTERT mRNA expression, suggesting hTERT is a major regulator of telomerase activity, and telomerase activation may play a critical role in esophageal carcinogenesis. Therefore, telomerase, especially hTERT can be used as a potential molecular biomarker of ESCC.

Carcinoma, Squamous Cell↗

PubMed2004

Development of an exonuclease protection mediated PCR bioassay for sensitive detection of Ah receptor agonists.

The aromatic hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates many of the biological and toxicological effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related chemicals. Here we developed a novel method to detect the presence of AhR ligands using Exonuclease Protection Mediated PCR bioassay (EPM-PCR). This assay measures the ability of a chemical to activate AhR DNA binding in vitro. In the presence of AhR ligand, an expected length PCR product was observed on electrophoresis, but no signal was detected in the absence of ligand. Real-time quantitative PCR was performed to quantify DNA bound to ligand:AhR complex. We obtained a standard curve with TCDD concentration to bound DNA copies in the range of 0.01 pM-10 nM of TCDD. Minimal detection limit of the assay was below 0.01 pM TCDD, and the whole detection time was less than 5 h. In comparison to the chemical-activated luciferase gene expression (CALUX) bioassay, EPM-PCR bioassay is more sensitive and easier to perform. These results suggest that this assay is useful for detection and quantification of TCDD and related AhR ligands in a cell-free system without the use of radioactivity.

Animals↗

PubMed2004

The mouse formin, FRLalpha, slows actin filament barbed end elongation, competes with capping protein, accelerates polymerization from monomers, and severs filaments.

Formins are a conserved class of proteins expressed in all eukaryotes, with known roles in generating cellular actin-based structures. The mammalian formin, FRLalpha, is enriched in hematopoietic cells and tissues, but its biochemical properties have not been characterized. We show that a construct composed of the C-terminal half of FRLalpha (FRLalpha-C) is a dimer and has multiple effects on muscle actin, including tight binding to actin filament sides, partial inhibition of barbed end elongation, inhibition of barbed end binding by capping protein, acceleration of polymerization from monomers, and actin filament severing. These multiple activities can be explained by a model in which FRLalpha-C binds filament sides but prefers the topology of sides at the barbed end (end-sides) to those within the filament. This preference allows FRLalpha-C to nucleate new filaments by side stabilization of dimers, processively advance with the elongating barbed end, block interaction between C-terminal tentacles of capping protein and filament end-sides, and sever filaments by preventing subunit re-association as filaments bend. Another formin, mDia1, does not reduce the barbed end elongation rate but does block capping protein, further supporting an end-side binding model for formins. Profilin partially relieves barbed end elongation inhibition by FRLalpha-C. When non-muscle actin is used, FRLalpha-C's effects are largely similar. FRLalpha-C's ability to sever filaments is the first such activity reported for any formin. Because we find that mDia1-C does not sever efficiently, severing may not be a property of all formins.

Actins↗

PubMed2004

DNA repair gene XRCC1 polymorphisms, smoking, and esophageal cancer risk.

To investigate the effect of X-ray repair cross complementing 1 (XRCC1) genetic polymorphisms on esophageal cancer risk, we determined XRCC1 polymorphisms at codon 194 (Arg --> Trp) and codon 399 (Arg --> Gln) in 135 patients with esophageal squamous cell carcinoma (ESCC) and 152 normal controls from hospitals. Although polymorphism at codon 194 was not associated with risk for ESCC, we found that the frequency of XRCC1 399 Gln/Gln genotype in ESCC patients (14.1%) was significantly higher than that in normal controls (3.3%), and that XRCC1 399 Gln/Gln genotype was associated with an increased risk of ESCC (odds ratio (OR) = 5.15, 95% confidence interval (CI): 2.42-0.93). In addition, we found that the risk for smoker increased 4.2-fold than non-smokers in the 399 Gln/Gln genotype (OR = 4.20, 95% CI: 2.37-7.44). These results suggest that XRCC1 399 Gln/Gln genotype may contribute to the risk of ESCC and modify risk associated with smoking.

Age Distribution↗

PubMed2004

Statins prevent oxidized low-density lipoprotein- and lysophosphatidylcholine-induced proliferation of human endothelial cells.

The proliferation of endothelial cells is induced by oxidized low-density lipoprotein (oxLDL) and its major component, lysophosphatidylcholine (LPC). The aim of this study was to investigate the effect of statins on the proliferation of endothelial cells derived from human umbilical cord veins (HUVEC). Cerivastatin, simvastatin and fluvastatin caused a dose-dependent inhibition of endothelial cell growth (n=12; P<.01) when using cell counts and [3H]-thymidine incorporation, respectively. The strongest inhibition of HUVEC proliferation was achieved at statin concentrations of 0.1 micromol/l (cerivastatin), 2.5 micromol/l (simvastatin) and 1 micromol/l (fluvastatin). Cell counts were significantly reduced from 22937+/-280.6 (control) to 7791+/-133.6 (cerivastatin), 7292+/-146.6 (simvastatin) and 6792+/-135.5 (fluvastatin) (n=12; P<.01). Interestingly, cell proliferation induced by oxLDL (10 microg/ml) and LPC (20 micromol/l) could be effectively prevented using statins at concentrations between 0.01 and 0.1 micromol/l (cerivastatin), 1 and 2.5 micromol/l (simvastatin) and 0.25 and 1 micromol/l (fluvastatin). This effect of the statins was abolished by preincubation with mevalonate (500 micromol/l). Our results demonstrate an interesting direct effect of statins on the proliferation of human endothelial cells induced by oxLDL and LPC, which may be beneficial to prevent vascular effects of these atherogenic lipids.

Cell Division↗

PubMed2004

bFGF activates endothelial Ca2+-activated K+ channels involving G-proteins and tyrosine kinases.

Activation of Ca2+-activated K+ channels (BK(Ca)) has been shown to be an important step in the basic fibroblast growth factor (bFGF)-induced proliferation of endothelial cells. In this study, we investigate the signaling cascades of BK(Ca) modulation by bFGF. Using the patch-clamp technique, bFGF (50 ng/ml) significantly increased the BK(Ca) open-state probability in cultured endothelial cells derived from human coronary arteries after 6 min (n=26, p<0.01), which lasted up the whole recording time of 60 min. After preincubation with pertussis toxin (100 ng/ml), bFGF superfusion did not cause a significant increase of BK(Ca) activity until 25 min had passed. When genistein was supplemented to the bath solution, a significant activation of BK(Ca) by bFGF was observed during a time interval of 6-20 min (n=17, p<0.01). In contrast, the addition of the inactive analogue daidzein did not change bFGF-induced activation of the BK(Ca). In conclusion, the results of the present study indicate that the early activation of the BK(Ca) by bFGF is mediated by G-protein-dependent mechanisms, whereas the later effect is due to a tyrosine kinase-dependent signaling pathway.

Cell Proliferation↗

PubMed2004

Engineered fusion hybrid vaccine of IL-18 gene-modified tumor cells and dendritic cells induces enhanced antitumor immunity.

Dendritic cell (DC)-tumor fusion hybrid vaccines that facilitate antigen presentation represent a novel powerful strategy in cancer immunotherapy. In our study, we investigated the antitumor immunity derived from the vaccination of fusion hybrids between engineered J558/IL-18 myeloma cells secreting Th1 cytokine IL-18 and DCs. DC/J558/IL-18 could secret a higher level of IL-18 than DCs, efficiently expressed J558 tumor antigen P1A, and enhanced ability of allogeneic T cell stimulation when compared to J558/IL-18. Our data showed that the immunization of BALB/c mice with DC/J558/IL-18 hybrids induced the most potent protective immunity against 1 x 10(6) cells with a J558 tumor challenge, compared to those immunized with the mixture of DCs and J558/IL-18, J558/IL-18, or J558. Furthermore, the immunization of mice with engineered DC/J558/IL-18 hybrids elicited stronger NK activity and J558 tumor-specific cytotoxic T lymphocyte (CTL) responses in vitro. In addition, DC/J558/IL-18 tumor cells into syngeneic mice induced a Th1 dominant immune response to J558 and resulted in tumor regression, which indicated that the antitumor effect mediated by DC/J558/IL-18 appeared to be dependent on TH1 cytokine production. These results demonstrate that the engineered fusion hybrid vaccines that combine Th1 gene-modified tumor with DCs may be an attractive strategy for cancer immunotherapy.

Animals↗

PubMed2004

Dose-dependent activation of Ca2+-activated K+ channels by ethanol contributes to improved endothelial cell functions.

BACKGROUND: Regular moderate alcohol (EtOH) intake seems to protect against both coronary artery disease and ischemic stroke, whereas the risk increases with heavy EtOH consumption. Effects of EtOH on endothelial cell function may be relevant to these disparate effects. Potassium channels play an important role in the regulation of endothelial cell functions. Therefore, we investigated whether Ca-activated K channels (BKCa) are modulated by EtOH. Furthermore, we examined whether EtOH-induced changes of endothelial nitric oxide (NO) formation and cell proliferation are due to BKCa activation. METHODS: The patch-clamp technique was used to investigate BKCa activity in cultured human umbilical vein endothelial cells (HUVEC). NO formation was analyzed by using the fluorescence dye 4,5-diaminofluorescein. Endothelial proliferation was examined by using cell counts and measuring [H]thymidine incorporation. RESULTS: EtOH dose-dependently (10-150 mmol/liter) modulated BKCa-activity, with the highest increase of open-state probability at a concentration of 50 mmol/liter (n = 13; p < 0.05). Inside-out recordings revealed that this effect was due to direct BKCa activation, whereas open-state probability was not changed in cell-attached recordings after pertussis toxin preincubation. EtOH (10 and 50 mmol/liter) caused a significant increase of NO levels, which was blocked by the highly selective BKCa inhibitor iberiotoxin (100 nmol/l; n = 30; p < 0.05). Higher concentrations of EtOH (100 and 150 mmol/liter) significantly reduced NO synthesis (n = 30; p < 0.05). Both methods revealed a significant increase of HUVEC proliferation, which was inhibited by iberiotoxin (n = 30; p < 0.05). At a concentration of 150 mmol/liter, EtOH caused a significant reduction of endothelial proliferation. CONCLUSIONS: EtOH directly activates BKCa in HUVEC, leading to an increase of endothelial proliferation and production of NO. These results indicate a possible beneficial effect of low-dose EtOH on endothelial function, whereas higher concentrations must be considered as harmful.

Cell Proliferation↗

PubMed2004

Cerivastatin activates endothelial calcium-activated potassium channels and thereby modulates endothelial nitric oxide production and cell proliferation.

Statins are known to counteract the process of arteriosclerosis by exerting direct pleiotropic effects on vascular endothelium. The aim of this study was to investigate a possible effect of cerivastatin on endothelial Ca(2+)-activated K+ channels (BK(Ca)) and to assess their contribution to cerivastatin-mediated changes of endothelial nitric oxide (NO) production and proliferation. Membrane potential was measured using bis-1,3-dibutylbarbituric acid-trimethine oxonol-fluorescence imaging. Patch-clamp recordings of BK(Ca) were performed on cultured human umbilical vein endothelial cells. NO production was measured using 4,5-diaminofluorescein-fluorescence imaging and a [(3)H]cGMP RIA. Proliferation was analyzed by means of cell counts and [(3)H]thymidine incorporation (TI). Cerivastatin (0.001 to 0.05 micromol/L) caused a significant membrane hyperpolarization (n = 30; P < 0.05). This effect was abolished using the BK(Ca) inhibitor iberiotoxin (IBX; 100 nmol/L). The addition of mevalonate (500 micromol/L) blocked the BK(Ca) activation induced by cerivastatin (n = 19; P < 0.05). Endothelial cGMP level was increased by acetylcholine (ACh; 1 micromol/L). The combination of ACh and cerivastatin additionally increased cGMP levels, with a maximum at 0.03 micromol/L cerivastatin (84%; n = 10, P < 0.01). ACh-induced increase of cGMP-level was significantly reduced by IBX (n = 10, P < 0.01) as it was with all combined administrations of ACh and cerivastatin. 4,5-Diaminofluorescein-fluorescence measurements revealed a significant increase of NO levels by cerivastatin, which was abolished by IBX (n = 30; P < 0.05). Cell counts and TI demonstrated significant inhibition of human umbilical vein endothelial cell proliferation with a maximum at 0.03 micro mol/L (cell count, -32.2%; TI, -70%; n = 12; P < 0.01). These data show that cerivastatin activates endothelial BK(Ca), which plays an important role in the signaling of cerivastatin-mediated endothelial NO production and proliferation.

Cell Division↗

PubMed2004

[The mechanism of topotecan resistance in ovarian cancer cell line].

OBJECTIVE: To study the mechanism of topotecan (TPT) resistance in ovarian cancer cell line. METHODS: A TPT-resistant ovarian cancer cell line A2780/TPT established in this laboratory was used in this study. Intracellular rhodamine fluorescence intensity of the TPT-resistant cells and parental cells were measured by flow cytometry. The gene expression of membrane protein transporter such as transporter P-glycoprotein (P-gp), multidrug resistance associated protein (MRP), breast cancer resistance protein (BCRP) was evaluated by RT-PCR. The antisense-phosphorothioate oligonucleotide (ASODN) including a translation initiation site of BCRP mRNA was transferred into resistant cells by liposome. RESULTS: Intracellular rhodamine fluorescence intensity of the resistant cells was 31.19% of that in the parental cells (P < 0.01). No expression of P-gp was demonstrated, and that of MRP was very weak in the TPT-resistant cells (relative expression value = 0.057). BCRP was overexpressed in the TPT-resistant cells (relative expression = 0.66), but not in the parental cells. Transfer of ASODN into resistant cells resulted in a 59.42% reduction of BCRP gene expression (P < 0.05) and an obviously increased intracellular rhodamine fluorescence intensity from 5.42 to 16.63 (P < 0.05). CONCLUSION: The overexpression of BCRP which mediated drug efflux may play an important role in the induction of TPT-resistance in ovarian cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

[An efficient macro-method of genomic DNA isolation from Actinidia chinensis leaves].

It is a difficult problem to isolate high quality DNA from plants containing a high contents of polyphenolics and polysaccharose, such as Actinidia plant. The protocol described in this paper is a modified CTAB (hexadecyltrimethylammonium bromide) method. High quality genomic DNA can be isolated from Actinidia plant using the improved method. The DNA is good enough for Southern blot and other uses in DNA research. The protocol is also efficient for quick and macro-DNA extraction.

Actinidia↗