Biomedical subjects

Youngmi Kim

Publications and source records attributed to Youngmi Kim.

10 recordsLinked to original sources

PubMed2006

TC1(C8orf4) correlates with Wnt/beta-catenin target genes and aggressive biological behavior in gastric cancer.

PURPOSE: We have recently reported that TC1(C8orf4), a small protein present in vertebrates, functions as a novel regulator of the Wnt/beta-catenin pathway. TC1 up-regulates beta-catenin target genes that are implicated in the aggressive behavior of cancers. Our aim was to investigate the clinical and pathobiological relevance of TC1 in gastric cancer. EXPERIMENTAL DESIGN: The expression of TC1 was analyzed using tissue microarray in correlation with clinicopathologic variables and beta-catenin target genes in 299 gastric cancers. The biological effects of TC1 on Matrigel invasiveness and the proliferation of cancer cells were analyzed. TC1 expression was analyzed in gastric cancer cells after serial peritoneal implantation in nude mice. RESULTS: TC1 expression was present in 111 carcinomas (37.1%), correlating with tumor stage (P < 0.002), poor differentiation (P < 0.001), lymphatic infiltration (P < 0.005), and lymph node metastasis (P < 0.006). TC1 also correlated with poor survival in diffuse type carcinomas (P < 0.0001), and even in patients with lymph node metastasis (P < 0.0014). TC1 also correlated with the expression of beta-catenin target genes including laminin gamma2, metalloproteinase-7 and metalloproteinase-14, cyclin D1, c-Met, and CD44. TC1 enhanced Matrigel invasiveness and proliferation, supporting its role in the aggressive biological behavior of cancers. The expression of TC1 increased in MKN45 cells after serial peritoneal seeding in nude mice. CONCLUSIONS: Our data suggests that TC1 coordinates the up-regulation of Wnt/beta-catenin target genes that are implicated in the aggressive biological behavior of cancers. The strong clinical relevance, even in patients with lymph node metastasis, suggested that TC1 could be a potential therapeutic target of advanced gastric cancers.

Animals↗

PubMed2006

TC1(C8orf4) is upregulated by IL-1beta/TNF-alpha and enhances proliferation of human follicular dendritic cells.

Follicular dendritic cells (FDC) play crucial roles in immune regulation. TNF-alpha has been shown to be essential to the FDC network. However, the molecular regulation of FDC proliferation has not been characterized. Here, we show that TC1(C8orf4), a novel positive regulator of the Wnt/beta-catenin pathway in vertebrates, is upregulated by IL-1beta and TNF-alpha in the human FDC-like line HK. TC1 enhances HK cell proliferation, while TC1-knockdown inhibits the proliferation induced by IL-1beta, suggesting a role of TC1 as a regulator of FDC proliferation. The regulation by pro-inflammatory cytokines suggests that TC1 might be implicated in linking local inflammation to immune response by stimulating FDC.

Base Sequence↗

PubMed2006

Rapid pyrazinamide susceptibility testing of Mycobacterium tuberculosis by flow cytometry.

The resurgence of tuberculosis along with the increased resistance of Mycobacterium tuberculosis has emphasized the need for timely susceptibility testing for control of the disease. Previous studies have shown that rapid susceptibility testing can be accomplished for isoniazid, ethambutol, and rifampin using the flow cytometric assays. In this study we compared the flow cytometric susceptibility assay with the BACTEC TB 460 and BACTEC MGIT 960 for pyrazinamide (PZA). There was 93% agreement between the BACTEC MGIT 960 and the flow cytometric methods for 100 microg/mL of PZA. Additionally, there was a 95% and 86% agreement between the BACTEC TB 460 and flow cytometric methods for 50 microg/mL and 100 microg/mL of PZA, respectively. These findings show that susceptibility testing by the flow cytometric assay is accurate. Most importantly, susceptibility results by the flow cytometric assay were available 24 h after initiation of the testing procedure. The advantages of simplicity, speed and accuracy make the flow cytometric susceptibility assay an immediate impact technology to improve patient care.

Antitubercular Agents↗

PubMed2006

Evaluation of 5-aminosalicyltaurine as a colon-specific prodrug of 5-aminosalicylic acid for treatment of experimental colitis.

We previously reported that 5-aminosalicyltaurine (taurine-conjugated 5-ASA, 5-ASA-Tau) showed a potential as a colon-specific prodrug of 5-aminosalicylic acid (5-ASA) by in vitro evaluation. In this report, we in vivo-evaluated 5-ASA-Tau as a colon-specific prodrug for treatment of experimental colitis. Taurine conjugation of 5-ASA greatly reduced absorption of 5-ASA from the intestine. Oral administration of taurine-conjugated 5-ASA not only increased the colonic delivery efficiency of 5-ASA but also decreased the systemic absorption of free 5-ASA as compared with that of 5-ASA and, moreover, taurine is similarly effective to known colon-specific carriers for 5-ASA, glycine and aspartic acid, suggesting that taurine conjugation is an efficient way to increase the therapeutic effect and to reduce the adverse effects of 5-ASA. Intracolonic treatment with combined 5-ASA/taurine additively ameliorated TNBS-induced colitis rats indicating that taurine acted as not only a promoiety but also a therapeutically active agent. Furthermore, 5-ASA-Tau is slightly more effective than sulfasalazine in alleviating the colonic inflammation induced by TNBS. Taken together, our data suggest that 5-ASA-Tau is a potential colon-specific prodrug of 5-aminosalicylic acid with improved therapeutic activity against inflammatory bowel disease.

Aminosalicylic Acids↗

PubMed2006

TC1 (C8orf4) enhances the Wnt/beta-catenin pathway by relieving antagonistic activity of Chibby.

The Wnt/beta-catenin pathway has been implicated in human cancers. Here, we show that TC1 (C8orf4), a small protein present in vertebrates, functions as a positive regulator of the pathway. TC1 interacts with Chibby (Cby) and thereby enhances the signaling pathway by relieving the antagonistic function of Cby on the beta-catenin-mediated transcription. Upon coexpression in mammalian cells, TC1 redistributes from nucleolus to nuclear speckles, where it colocalizes with Cby. TC1 up-regulates the expression of beta-catenin target genes that are implicated in invasiveness and aggressive behavior of cancers, such as metalloproteinases, laminin gamma2, and others. Our data indicate that TC1 is a novel upstream regulator of the Wnt/beta-catenin pathway that enhances aggressive behavior of cancers.

Carrier Proteins↗

PubMed2005

Highly emissive conjugated polymer excimers.

Conjugated polymers often display a decrease of fluorescence efficiency upon aggregation due in large part to enhanced interpolymer interactions that produce weakly emissive species generally described as having excimer-like character. We have found that poly(phenylene ethynylene)s with fused pendant [2.2.2] ring structures having alkene bridges substituted with two ester groups function to give highly emissive, broad, and red-shifted emission spectra in the solid state. To best understand the origin of this new solid-state emissive species, we have performed photophysical studies of a series of different materials in solution, spin-coated thin films, solid solutions, and Langmuir films. We conclude that the new, red-shifted, emissive species originate from excimers produced by interchain interactions being mediated by the particular [2.2.2] ring system employed. The ability to design structures that can reliably produce highly emissive conjugated polymer excimers offers new opportunities in the emission tailoring of electroluminescence and sensory devices.

Journal Article↗

PubMed2005

High ionization potential conjugated polymers.

We report the synthesis of a series of poly(p-phenylene ethynylene)s (PPEs) with high ionization potentials and associated high excited-state electron affinities. Their photophysical properties were investigated using steady-state and time-resolved fluorescence techniques. The ionization potentials of the polymer thin films were determined using ultraviolet photoelectron spectroscopy (UPS), and those with the highest ionization potentials displayed high sensitivity for the detection of electron-donating aromatic compounds. The effects of sterics, chemical structure, and electronic properties on the polymers' sensory responses were investigated by fluorescence quenching experiments in both solution and solid thin films. In addition, we report that in some cases the excited-state charge-transfer complexes (exciplexes) of the PPEs with analytes were observed. These latter effects provide promising opportunities for the formation of sensitive and selective chemical sensors.

Journal Article↗

PubMed2005

Metabolic and pharmacological properties of rutin, a dietary quercetin glycoside, for treatment of inflammatory bowel disease.

PURPOSE: Orally administered rutin reportedly ameliorates 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis of rats. We investigated the metabolic and pharmacological properties of rutin underlying the rutin-mediated amelioration of the rat colitis. METHODS: Apparent partition coefficients of rutin and its aglycone quercetin were compared. The biochemical/chemical stability of rutin was examined in the contents of various segments of gastrointestinal tracts of rats. Inflammatory indices were determined in the colitis rats after oral administration of rutin or rectal administration of quercetin. In human colon epithelial cells, the effect of quercetin on tumor necrosis factor-alpha (TNF-alpha)-induced nuclear factor kappa B (NFkappaB) activation was examined. RESULTS: The sugar residue in rutin greatly lowered the apparent partition coefficient and was rapidly deglycosylated to liberate quercetin in the cecal contents, whereas it was stable in the contents of the upper intestine. Not only oral administration of rutin but also rectal administration of quercetin remarkably ameliorated TNBS-induced colitis rats, indicating that quercetin liberated from rutin is therapeutically active. Furthermore, quercetin dose-dependently inhibited an inflammatory signal TNF-alpha-dependent NFkappaB activation. CONCLUSIONS: Our data suggest that rutin acted as a quercetin deliverer to the large intestine and its anti-inflammatory action in TNBS-induced colitis rats may be through quercetin-mediated inhibition of TNF-alpha-induced NFkappaB activation.

Animals↗

PubMed2004

Ultra-photostable n-type PPVs.

Poly(p-phenylenevinylene)s containing trifluoromethyl substituted aromatic rings (CF3-PPVs) exhibit high photooxidative stability to give robust materials suitable for demanding applications.

Journal Article↗

PubMed2004

Hyperconjugative and inductive perturbations in poly(p-phenylene vinylenes).

New polymers having high solid-state fluorescence quantum yields and the ability to tune their electron affinity without effecting their band gap using hyperconjugative interactions is reported. The novel three-dimensional poly(phenylene vinylenes) having [2.2.2] bicyclic ring systems shown were synthesized, and the different hyperconjugative perturbations provide differential fluorescence sensory quenching responses to electron-rich and electron-deficient analytes in solution and solid thin films.

Journal Article↗