Biomedical subjects

Shan-Shan Li

Publications and source records attributed to Shan-Shan Li.

6 recordsLinked to original sources

PubMed2006

Time-dependent organization and wettability of decanethiol self-assembled monolayer on Au(111) investigated with STM.

A detailed study on the time-dependent organization of a decanethiol self-assembled monolayer (SAM) at a designed solution concentration onto a Au(111) surface has been performed with scanning tunneling microscopy (STM). The SAMs were prepared by immersing Au(111) into an ethanol solution containing 1 microM decanethiol with different immersion times. STM images revealed the formation process and adlayer structure of the SAMs. It was found that the molecules self-organized into adlayers from random separation to a well-defined structure. From 10 s, small domains with ordered molecular organization appeared, although random molecules could be observed on Au(111) at the very initial stage. At 30 s, the SAM consisted of uniform short stripes. Each stripe consisted of sets of decanethiol mainly containing eight molecules. With the immersion time increasing, the length of the stripes increased. At 5 min, the alkyl chains overlapped each other between the adjacent stripes, indicating the start of a stacked process. After immersing Au(111) in decanethiol solution for 3 days, a densely packed adlayer with a (radical 3 x radical 3)R30 degrees structure was observed. The formation process and structure of decanethiol SAMs are well related to sample preparation conditions. The wettability of the decanethiolate SAM-modified Au(111) surface was also investigated.

Journal Article↗

PubMed2006

[Correlation of P27 expression and localization to phosphorylated AKT in non-small cell lung cancer].

BACKGROUND & OBJECTIVE: Inactivation of tumor suppressor gene plays an important role in tumorigenesis and tumor development. Functional inactivation of the tumor suppressor gene p27 in human cancer occurs either through the loss of expression or through phosphorylation-dependent cytoplasmic mislocalization. AKT, known as protein kinase B, represents a subfamily of serine/threonine protein kinases. Activated AKT (phosphorylated AKT, p-AKT) could promote cell cycle progression by modulating many effectors in cell cycle, including the expression and localization of P27. This study was to investigate the expression and localization of P27 protein in human non-small cell lung cancer (NSCLC), and further to explore its correlation to p-AKT. METHODS: The expression and subcellular localization of P27 and the expression of p-AKT in 80 cases of NSCLC and 35 cases of non-cancerous lung disease were detected by immunohistochemistry, and their correlations to clinicopathologic factors were statistically analyzed. RESULTS: The total and nuclear positive rates of p27 were significantly lower in NSCLC than in non-cancerous lung disease (72.5% vs. 94.3%, 46.3% vs. 94.3%, P<0.01). There were 21 cases of NSCLC with only cytoplasmic expression of P27, while no cytoplasmic expression alone was found in 35 cases of non-cancerous lung disease (P<0.01). The nuclear positive rate of P27 was significantly higher in NSCLC without lymph node metastasis than in NSCLC with lymph node metastasis (P<0.05), and higher in well-and moderately-differentiated NSCLC than in poorly-differentiated NSCLC (P<0.05). The nuclear and cytoplasmic expression of P27 has no correlation to clinicopathologic factors of NSCLC (P>0.05). The positive rate of p-AKT was significantly higher in NSCLC than in non-cancerous lung disease (78.8% vs. 0, P<0.05); it was significantly higher in well-and moderately-differentiated adenocarcinoma than in poorly-differentiated adenocarcinoma (95.0% vs. 50.0%, P<0.05). In NSCLC, the expression of p-AKT was positively correlated to the cytoplasmic expression of P27 (r=0.437, P<0.01), but had no correlation to the nuclear expression of P27 (r=0.175, P>0.05). CONCLUSIONS: Reduced nuclear expression or loss of expression of P27 may be associated to the development of NSCLC. The localization of P27 only in cytoplasm may be one of the characteristics of lung cancer cells. P-AKT might play a role in the cytoplasmic localization of P27, but has no correlation to its nuclear expression.

Adolescent↗

PubMed2005

Expression of human chorionic gonadotropin, CD44v6 and CD44v4/5 in esophageal squamous cell carcinoma.

AIM: To study the relationship between the expression of human chorionic gonadotropin (HCG), CD44v6, CD44v4/5 and the infiltration, metastasis of esophageal squamous cell carcinoma. METHODS: By labeled streptavidin-biotin technique, the expressions of HCG, CD44v6, and CD44v4/5 in 42 patients with esophageal squamous cell carcinoma were examined. RESULTS: The positive rate of HCG expression in patients with lymph node metastasis was 85.71% (18/21), higher than that (57.14%, 12/21) in those without lymph node metastasis (P<0.05). The positive rate of CD44v6 expression was 71.43% (15/21) in lymph node metastasis group, and 38.09% (8/21) in non-metastasis group; there was a significant difference between the two groups (P<0.05). The positive rate of CD44v4/5 expression was 76.19% (16/21) in lymph node metastasis group, and 42.86% (9/21) in non-metastasis group; there was also a significant difference between them (P<0.05). From grade I to grade III in differentiation, the positive rate of HCG expression was 84.62% (11/13), 70.59% (12/17) and 58.33% (7/12), respectively; there was no significant difference among them (P>0.05). The positive rate of CD44v6 expression in grades I-III of cancer tissues was 76.92% (10/13), 52.94% (9/17), and 33.33% (4/12) respectively; there was no significant difference among them. The positive rate of CD44v4/5 expression in grades I-III of cancer tissues was 69.23% (9/13), 64.71% (11/17), and 41.67% (5/12) respectively; there was no significant difference among the three groups. There was no correlation between the positive rates of HCG and CD44v6, CD44v4/5 expression. Cancer cells in carcinomatous emboli and those infiltrating into vascular wall strongly expressed HCG, CD44v6, and CD44v4/5. CONCLUSION: Expression of HCG, CD44v6, and CD44v4/5 in esophageal squamous cell carcinoma is related to its infiltration and metastasis. HCG, CD44v6, and CD44v4/5 have different effects on the infiltration and metastasis of esophageal squamous cell carcinoma.

Adult↗

PubMed2005

Promoter methylation and differential expression of pi-class glutathione S-transferase in endometrial carcinoma.

Pi-class glutathione S-transferase (GSTP1), located on chromosome 11q13, codes for a phase II metabolic enzyme that detoxifies reactive electrophilic intermediates. The protein also interacts with steroid hormones in the human body. The role of GSTP1 in endometrial carcinoma has not been reported. In this study, we aimed at determining the expression of GSTP1 in relation to the epigenetic and genetic changes of the gene in endometrial carcinoma. The GSTP1 protein and mRNA expression was assessed by immunohistochemistry on tissue microarray and quantitative real-time reverse transcriptase-polymerase chain reaction, respectively. Its methylation status was studied by methylation-specific polymerase chain reaction and bisulfite sequencing. Possible mutations in coding region of GSTP1 were assessed by cDNA sequencing. Ninety-seven cases of endometrial carcinoma with available tissue blocks and clinical data were studied. Our results showed that 68.0% (66 of 97) of the cases showed reduced protein expression while 64% (16 of 25) showed reduced mRNA expression; 30.9% (30 of 97) of the cases demonstrated methylated alleles in at least one of the six methylation-specific polymerase chain reaction reactions. The methylation status significantly correlated with reduced protein expression (P = 0.008) and reduced mRNA expression (P = 0.003). Methylation at non-CpG sites including CpCpG trinucleotides and CpT dinucleotides were also observed. cDNA sequencing did not reveal genetic alterations in coding region of the gene. The extent of myometrial invasion was found to be significantly correlated with both the methylation status (P = 0.009) and the protein expression (P = 0.036) of the GSTP1 gene. We postulated that hypermethylation of the GSTP1 gene promoter region may act as a dynamic regulation mechanism contributing to reduced GSTP1 expression, which is associated with myometrial invasion potential of the endometrial carcinoma.

Adult↗

PubMed2005

[Differential display technique and its progress].

Differential display technique is an important method to isolate differentially expressed gene. Comparing to other methods like representational difference analysis, suppression subtractive hybridization and serial analysis of gene expression, differential display technique is used in higher frequency. Since it was established in 1992, it has overcome many disadvantages and widened its practical fields through improvements and enhancements by global researchers. In this paper the principle and the main advantages and disadvantages of differential display technique were briefly introduced. Meanwhile, the four progressed aspects in designing primer, reducing false positives, identifying differentially expressed gene and techniques derived from DD were introduced in detail.

Blotting, Northern↗

PubMed2005

Oral immunization of mice with vaccine of attenuated Salmonella typhimurium expressing Helicobacter pylori urease B subunit.

OBJECTIVE: To prepare the live recombinant vaccine of attenuated Salmonella typhimurium SL3261 expressing Helicobacter pylori (H. pylori) B subunit (UreB) and to determine whether it could be used as an oral vaccine against H. pylori infection. METHODS: Using genomic DNA of H. pylori Sydney strain (SSI) as template, the H. pylori UreB gene fragment was amplified by PCR and subcloned into the expression vector pTC01. The recombinant plasmid pTC01-UreB was then transferred into LB5000 to obtain modified forms, and further conversed into the attenuated Salmonella typhimurium SL3261 to obtain recombinant SL3261/pCT01-UreB as an oral immunization reagent, which was then used to orally immunize Balb/c mice twice at a three-week interval. Twelve weeks later, anti-UreB IgA antibodies in intestinal fluid and IgG antibodies in sera were determined by ELISA. The relating data in control groups (including body weight, gastric inflammation, etc.) were also collected. RESULTS: The sequencing analysis showed that the UreB gene fragment amplified by PCR was consistent with the sequence of the H. pylori UreB gene. The restriction enzyme digestion revealed that the correct pTC01-UreB was obtained. SDS-PAGE and Western blot showed that a 61KD protein was expressed in SL3261/pTC01-UreB, which could be recognized by anti-H. pylori UreB antiserum and was absent in the control containing only Salmonella typhimurium SL3261 strain. The multiple oral immunization with SL3261/pTC01-UreB could significantly induce H. pylori specific mucosal IgA response as well as serum IgG responses. IFN-gamma and IL-10 levels were significantly increased in SL3261/pTC01-UreB group, and no obvious side effect and change in gastric inflammation were observed. CONCLUSION: The attenuated vaccine of Salmonella typhimurium expressing H. pylori UreB can be used as an oral vaccine against H. pylori infection.

Animals↗