The tetragonal pyramid stripper is a new high-efficiency stripper developed by PetroChina Qingyang Petrochemical Co., Ltd. The unique structure has provided multiple passes and multiple layer spaces for the sufficient contacting of catalysts with steam. The catalysts can flow freely and there is no blocking, bridging and build-up, and there is no risk in normal operation. A good layout has been designed in consideration of easy installation, maintenance and removal, and design bottom size is 370 mm × 370 mm. In addition, the thermal stress is also considered. The 20R steel is upgraded to 0Crl9Ni9, and the support beams and associated members are applied with wear-resistant coatings. When the tetragonal pyramid stripper was installed in a 600,000 TPY FCC unit to replace the existing round cone plate baffle cone stripper, the LPG yield was increased by 1.03 %, the gasoline + light diesel yield was raised by 1.83%, the coke on spent catalysts was reduced by 0. 23%, the coke make was lowered by 1. 04%. The annual economic benefit is 2. 0 million Yuan (RMB).

Objective: To investigate telomerase activity and telomerase expression in the human gastric carcinoma cell line SGC7901 and its multi-drug resistant subcultured cell line SGC7901/VCR, and to search for a new target within the drug-resistance mechanism of the gastric carcinoma cell line. Methods: Silver staining TRAP(telomeric repeat amplification protocol) assay was used to detect telomerase activity. Semi-quantitative reverse transcriptase PCR was employed to detect hTERT, Mad1 and c-Myc mRNA expression. Plasmid (pGL3B-TRTP) was transfected into SGC7901/VCR and SGC7901. Expression of the reporter gene in the cell lysates was assayed by a dual luciferase reporter assay system. Results: Both telomerase activity and telomerase hTERT mRNA expression in SGC7901/VCR cells were higher than those in SGC7901 cells. hTERT promoter activity was significantly higher in SGC7901/VCR than in SGC7901. c-Myc mRNA expression was detected in SGC7901/VCR, but Mad1 mRNA was not. In SGC7901, both c-Myc and Mad1 mRNA expression could be detected and c-Myc mRNA expression was higher than that in SGC7901/VCR. Conclusion: Telomerase activity in SGC7901/VCR was higher than that in SGC7901, and the high level of telomerase hTERT gene transcription and expression in SGC7901/VCR was correlated with drug-resistance. Mad1 and c-Myc expression may contribute to hTERT transcription and telomerase activity.

OBJECTIVE:To investigate the relationship between promoter of ER methylation and ER mRNA expression and clinicopathologic features in hepatocellular carcinoma (HCC). And to observe the effects of 5-aza-2-deoxycytidine (5-aza-dc) in regulating ER mRNA expression. METHODS: Promoter methylation of the ER gene was determined by methylation-specific PCR (MSP) in HCC and non-tumor cases. And the expression of ER mRNA was investigated by RT-PCR. Two hepatic cancer cell lines SMMC-7721 and HepG2 were treated with DNA methyltransferase inhibitor, 5-aza-dc. RESULTS: Promoter of the ER gene was methylated in 60.0%(18/30)of HCC and 30.0%(9/30)of non-tumor tissues,respectively. Statistically significant association was found between the status of aberrant methylation in HCC and non-tumor case, χ2=5.455,P=0.037. The expression of ER mRNA was 40.0% (12/30) in HCC, while the expression of ER mRNA was 22.2% and 66.7% in methylated HCC cases and unmethylated HCC cases, respectively. An inverse correlation was found between promoter methylation and ER mRNA transcript levels in HCC, χ2=5.93,P=0.024. Meanwhile, there was a significant association between methylation of the ER gene and serum AFP level, χ2=12.13,P=0.001. The study shows that low micromolar concentrations of 5-aza-dc induce the ER mRNA expression of in HCC cancer lines. CONCLUSION: Promoter methylation of ER gene is a frequent event in HCC and may contribute to pathogenesis of HCC through silencing ER mRNA expression.

Objective: To investigate the relationship between DNA methylation and the expression of human telomerase reverse transcriptase (hTERT) in normal liver L02 cells and hepatocellular carcinoma cell line SMMC-7721 and to study the effect of demethylation induced with 5'-aza-dC by observing hTERT expression and telomerase activity. Methods: The methylation pattern of hTERT in cell lines was assayed by methylation-specific PCR (MSP). Demethylation in cultured cells was induced by adding 5'-aza-dC. The expression of hTERT was measured using RT-PCR and telomerase activity was detected by TRAP-ELISA. Results: In the L02 cells the hTERT promoter was methylated and the cells had decreased hTERT expression, while the expression level of hTERT was much higher in the SMMC-7721 cells. The expression of hTERT was upregulated and telomerase activity was increased in L02 cells after demethylation. Conclusion: hTERT expression may be repressed by methylation of its promoter, and abnormal demethylation of the hTERT promoter may play an important role in the development of hepatocellular carcinoma.

BACKGROUND:Aberrant promoter methylation is an important mechanism for gene silencing.AIMS:To evaluate the promoter methylation status of p300 gene in patients with oesophageal squamous cell carcinoma (OSCC).METHODS:The methylation status of p300 promoter was analysed by methylation-specific PCR (MSP) in 50 OSCC tissues and the matching non-cancerous tissues. Oesophageal cancer cell lines (ECa-109 and TE-10) were treated with the demethylation agent 5-aza-2'-deoxycytidine (5-Aza-CdR), and p300 mRNA expression was detected by RT-PCR.RESULTS:p300 methylation was found in 42% (21/50) of the OSCC tissues, but in only 20% (10/50) of the corresponding non-cancerous tissues (p = 0.017). In OSCC samples, 65% of those with deep tumour invasion (adventitia) and 63% samples with metastasis revealed p300 promoter methylation (p<0.05). p300 mRNA expression was observed in 19.0% (4/21) of methylated tumours and 58.6% (17/29) of unmethylated tumours (p = 0.005). In addition, p300 mRNA expression was observed in 40% (4/10) of methylated non-neoplastic tissues and 87.5% (35/40) of unmethylated non-tumours (p = 0.001). The demethylation caused by 5-Aza-CdR increased the p300 mRNA expression levels in oesophageal cancer cell lines.CONCLUSIONS:p300 transcription silenced by promoter hypermethylation could play a role in the pathogenesis of oesophageal squamous cell carcinoma.

PURPOSE:CpG island methylator phenotype (CIMP) involves hypermethylation targeted toward the promoters of multiple genes. To gain insight into the role of epigenetic aberration of tumor-related genes in hepatocarcinogenesis, we determined a hypermethylation profile in hepatocellular carcinoma (HCC). EXPERIMENTAL DESIGN:We examined the promoter methylation status of nine genes in 50 HCCs, 50 paired nontumor tissues, and 6 normal liver tissues by methylation-specific PCR. CIMP+ was defined as having five genes that are concordantly methylated. RESULTS:The frequency of promoter methylation of nine genes in 50 HCCs varied from 10% in P53 to 94% in c-Myc. The methylation status of P14, P15, P16, ER, RASSF1A, WT1, and c-Myc was significantly correlated with HCC and nontumor tissues (P<0.05). Hypermethylation of one or more genes was found in 96% of HCC. CIMP was more frequent in HCC than in nontumor tissues (70% and 12%, P<0.001). There is a significant association between CIMP and methylation of P14, P15, P16, ER, RSAAF1A, and WT1 (P<0.05) and serum alpha-fetoprotein (AFP) level (P=0.017). CIMP+ was more frequent in HCC with AFP>or=30 microg/L than those with AFP<30 microg/L (P=0.005). In addition, the promoter hypermethylation of P15 and P16 was associated with elevated serum AFP levels in 35 HCC samples with CIMP+ (P<0.05). CONCLUSIONS:Positive correlation of CIMP and AFP levels in HCC suggests that CIMP can serve as a molecular marker of late-stage HCC development.

To study the clinical significance of telomerase activity and human telomerase reverse transcriptase (hTERT) mRNA expression for differential diagnosis of malignant and benign liver lesions.