Biomedical subjects

Yingxin Li

Publications and source records attributed to Yingxin Li.

5 recordsLinked to original sources

PubMed2006

Tumor-specific gene expression patterns with gene expression profiles.

Gene expression profiles of 14 common tumors and their counterpart normal tissues were analyzed with machine learning methods to address the problem of selection of tumor-specific genes and analysis of their differential expressions in tumor tissues. First, a variation of the Relief algorithm, "RFE_Relief algorithm" was proposed to learn the relations between genes and tissue types. Then, a support vector machine was employed to find the gene subset with the best classification performance for distinguishing cancerous tissues and their counterparts. After tissue-specific genes were removed, cross validation experiments were employed to demonstrate the common deregulated expressions of the selected gene in tumor tissues. The results indicate the existence of a specific expression fingerprint of these genes that is shared in different tumor tissues, and the hallmarks of the expression patterns of these genes in cancerous tissues are summarized at the end of this paper.

Algorithms↗

PubMed2006

Actin-based features negatively regulated by protein kinase C-epsilon.

Cells exposed to phorbol 12-myristate 13-acetate (PMA) undergo a choreographed sequence of morphological changes. Some of these, including stimulation of membrane ruffles and the later appearance of stress fibers, rely on remodeling of the actin cytoskeleton. Although this process is poorly understood, it is important, because the same features are affected during oncogenic transformation. PMA also activates protein kinase C (PKC). Enzyme activation is followed by degradation. Either process might affect the remodeling of actin. The present studies determined whether any PKC isozymes were subject to degradation in tracheal epithelial cells by quantifying the amount of each isozyme present after PMA exposure. PKC-epsilon was the only isozyme to show declining content correlated with increased stress fiber accumulation. Stress fibers increased between 5 and 10 h, whereas PKC-epsilon declined to 38% of its starting value (95% confidence interval, 10-68%). The relationship could be fit by the function F(x) = 0.683 x exp[-0.841(x - 0.387)], where F is the frequency of fiber-containing cells and x is PKC-epsilon content. Fiber accumulation was further investigated after knockdown of PKC-epsilon with RNA interference and antisense oligodeoxynucleotide. Knockdown enhanced stress fibers in cells not yet exposed to PMA as well as the final frequency of fiber-containing cells after PMA exposure. With knockdown at both transcriptional and protein levels, approximately 15% of the original content was predicted and achieved, as judged from real-time PCR and PKC-epsilon content measurements. The results suggest that PKC-epsilon negatively regulates stress fibers, either by directly turning over one of their components or by regulating an upstream step affecting fiber organization.

Actins↗

PubMed2005

Asymmetric synthesis of 2,4,5-trisubstituted piperidines from sulfinimine-derived delta-amino beta-ketoesters. Formal synthesis of pseudodistomin B triacetate.

[reaction: see text] N-Sulfinyl delta-amino beta-ketoester enaminones, a new sulfinimine-derived chiral building block, undergoes, on hydrolysis in one pot, an intramolecular Michael addition followed by a retro-Michael-type elimination to give enantiopure 2,4,5-trisubstituted piperidines, a structural motif found in numerous biologically active alkaloids. This new chiral building block is readily prepared by treating N-sulfinyl delta-amino beta-ketoesters with dimethylformamide dimethyl acetal. This new protocol was illustrated with a concise formal asymmetric synthesis of marine alkaloid pseudodistomin B triacetate.

Acetals↗

PubMed2002

[Study of a new microwave applicator for hyperthermia treatment of uterocervical cancer].

A new microwave applicator for intracavitary hyperthermia treatment of uterocervical cancer has been designed and tested. Compared with the traditional microwave applicators, the exposed inner conductor of this applicator is replaced by a cone-helical antenna with the reflect shade. We confirm that the heat pattern of the applicator is shifted towards the tip in muscle tissue equivalent phantom material. The result indicates that this new applicator may play an important role in clinical use for treatment.

Equipment Design↗

PubMed2002

[Clinical and pathological characteristics and pathogenesis of autoimmune hepatitis].

BACKGROUND: To explore the clinical and pathological characteristics and pathogenesis of autoimmunohepatitis (AIH). METHODS: The serum and liver biopsy specimens and clinical data of 26 cases with patients with AIH were analyzed and scored according to the criteria of International autoimmune hepatitis (IAIHG, 1999). The changes of dendritic cells (DC) in the liver tissues were observed with a panel of DC markers (CD-80/B7-1, CD-86/B7-2, CD-1a and HLA-DR) and immunohistochemistry, and the activation of hepatic stellate cells (HSC) and the expression of TGF-alpha were also detected. Liver tissue specimens from 10 patients with chronic viral hepatitis B and C respectively and 5 normal liver specimens were chosen as controls. RESULTS: Mean aggregate scores of 26 AIH cases, including 21 cases of type B (80.8%) and 5 cases of type C (19.2%), which were 18.6 +/- 1.4 and 19.1 +/- 2.1 respectively. There were significant differences between the type B and type C in the average age levels of serum ALT and AST, and alpha-Glo (P <0.001 or P< 0.01 or P <0.05). Histological features of all the AIH liver tissues showed the lesions of chronic active hepatitis such as interface hepatitis/piecemeal necrosis (100%), obvious lobular inflammation (type B 95.2%, type C 100%), bridging necrosis (57.1% type B, 80.0% type C, P<0.05), rosetting of liver cells (71.4% type B, 100% type C, P<0.01), central lobular confluent necrosis (33.3% type B, 80.0% type C, P<0.001), predominant plasmacytic infiltration (type B 95.2%, type C 20.0%, P<0.001). The rates of increased and concentrated DC in the portal and lobular areas, especially in the active lesions in type B and type C AIH were 85.7% (18/21) and 5/5 respectively. It was found that DC and lymphocytes surrounded the hepatocytes which partly expressed HLA-DR antigen, while there were no or a few HLA-DR positive hepatocytes in controls. Meanwhile, the number of alpha-SMA positive HSC and the expression of TGF- were obviously increased in AIH liver tissues. CONCLUSIONS: Several clinical and pathological features of AIH were identified in this study. As an antigen-presenting cell, DC might play an important role in the pathogenesis of AIH. In China, sub-type B of AIH might be more frequent than sub-type C and there were differences in clinical aspects, serology and pathology between the two types.

Adolescent↗