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Biomedical subjects

Y S Cho

Publications and source records attributed to Y S Cho.

At least 73 records · Page 4Linked to original sources
PubMed2000

Narrow internal auditory canal syndrome: parasaggital reconstruction.

Narrow internal auditory canal (IAC) syndrome is a malformation of the temporal bone, that is defined as an IAC diameter of only 1-2 mm on high-resolution computed tomographic scans (HRCT). This syndrome is known to be caused by the absence (aplasia or hypoplasia) of the vestibulocochlear nerve. We present a case of unilateral narrow IAC syndrome which was diagnosed by HRCT. The aplasia of the vestibulocochlear nerve was confirmed using parasigittal reconstruction magnetic resonance image (MRI). The IAC was composed of two separate canals, one of which contained a facial nerve and the other was empty with aplasia of the vestibulocochlear nerve.

Adolescent↗
PubMed2000

Sonographically guided ethanol sclerotherapy for benign thyroid cysts: results in 22 patients.

OBJECTIVE: We evaluate the efficacy and safety of sonographically guided ethanol sclerotherapy for benign thyroid cysts. SUBJECTS AND METHODS: We examined 22 patients with benign thyroid cysts (13 complex cysts and nine pure cysts) confirmed by fine-needle aspiration biopsy. Sonographically guided aspiration of the cystic fluid was followed by instillation of absolute ethanol (99.9%) into the cystic cavity: the injected volume of ethanol was 40-100% of the volume of fluid aspirated. The procedure was performed every 1 or 3 months for one or two sessions (mean, 1.2 sessions). Follow-up sonography was performed 1-10 months after the final session, and we observed patients after ethanol sclerotherapy for complications. RESULTS: The initial volume of the cysts ranged from 3.5 to 42 ml. In 21 patients, the volume of the cyst decreased or the cyst was obliterated. The volume of the cyst was reduced by 50-99% in 13 patients and by 1-49% in six patients, and the cyst was obliterated in two patients. In one patient, the volume of the cyst increased. The volume of ethanol instilled was significantly correlated with the volume reduction rate of the cyst. There was a difference in the volume reduction rate between patients in whom 10 ml or more of initial volume was used and those in whom less than 10 ml of initial volume was used; that is, the volume reduction rate of the group with the initial cyst volume of more than 10 ml was higher than that of the other group. Important long-standing and severe complications were not observed. CONCLUSION: Sonographically guided ethanol sclerotherapy is a safe and effective tool for the therapy of benign thyroid cysts.

Adult↗
PubMed2000

Significance of rectosigmoid polyp as a predictor of proximal colonic polyp.

The association between rectosigmoid polyps and polyps in the more proximal colon is still a matter of debate, and the need for colonoscopy in patients with rectosigmoid polyps that are detected by flexible sigmoidoscopy is controversial. The aim of this study was to determine whether or not certain characteristics of rectosigmoid polyps are associated with the presence and characteristics of proximal colonic polyps. Seven hundred and twenty-eight patients who underwent total colonoscopy between October 1995 and June 1998 and who had colorectal polyps were retrospectively analyzed. Patients with inflammatory bowel diseases, familial adenomatous polyposis, or any advanced cancer were excluded. The odds ratio (OR) and 95% confidence interval (CI) of prevalence of proximal colonic polyps according to the patients age and sex, as well as the characteristics of rectosigmoid polyps, were calculated. Advanced adenoma was defined as an adenoma larger than 10 mm or an adenoma of any size with villous component, high-grade dysplasia or invasive carcinoma. Among 728 patients with colorectal polyps, 356 patients (48.9%) had polyps only in the rectosigmoid region, 193 patients (26.5%) had polyps only in the proximal colon, and 179 patients (24.6%) had polyps in both the rectosigmoid and proximal colon. In 535 patients with rectosigmoid polyps, the prevalence of proximal colonic polyps, neoplastic polyps and advanced adenomas were 33.4%, 27.3% and 2.9%, respectively. The prevalence of proximal colonic polyps in patients with rectosigmoid polyps was found to be significantly related to the male gender and elderly patients, in addition to the neoplastic histology of the rectosigmoid polyps. However, the prevalence of the proximal colonic polyps was not related to the size, number and shape of rectosigmoid polyps. In 179 patients with both rectosigmoid and proximal colonic polyps, the characteristics of proximal colonic polyps such as size, number and shape were similar to those of rectosigmoid polyps. We recommend total colonoscopic examination in all patients with rectosigmoid adenomas, regardless of the size, number, and shape, especially in elderly males.

Adult↗
PubMed2000

CRE-decoy oligonucleotide-inhibition of gene expression and tumor growth.

Nucleic acid molecules with high affinities for a target transcription factor can be introduced into cells as decoy cis-elements to bind these factors and alter gene expression. This review discusses a synthetic single-stranded palindromic oligonucleotide, which self-hybridizes to form a duplex/hairpin and competes with cAMP response element (CRE) enhancers for binding transcription factors. This oligonucleotide inhibits CRE- and Ap-1-directed gene transcription and promotes growth inhibition in vitro and in vivo in a broad spectrum of cancer cells, without adversely affecting normal cell growth. Evidence presented here suggests that the CRE-decoy oligonucleotide can provide a powerful new means of combating cancers, viral diseases, and other pathological conditions by regulating the expression of cAMP-responsive genes.

Animals↗
PubMed1999

Extinction coefficients and midpoint potentials of cytochrome c(6) from the cyanobacteria Arthrospira maxima, Microcystis aeruginosa, and Synechocystis 6803.

Cytochrome c(6) is a soluble heme protein that serves as a photosynthetic electron transport component in cyanobacteria and algae, carrying electrons from the cytochrome bf complex to photosystem I. The rapid accumulation of cytochrome c(6) sequence data from a wide range of species, combined with significant advances in determining high resolution three-dimensional structures, provides a powerful database for investigating the relationship between structure and function. The fact that the gene encoding cytochrome c(6) can be readily modified in a number of species adds to the usefulness of cytochrome c(6) as a tool for comparative analysis. Efforts to relate cytochrome c(6) sequence information to structure, and structural information to function depend on knowledge of the physical and thermodynamic properties of the cytochrome from different species. To this end we have determined the optical extinction coefficient, the oxidation/reduction midpoint potential, and the pH dependence of the midpoint potential of cytochrome c(6) isolated from three cyanobacteria, Arthrospira maxima, Microcystis aeruginosa, and Synechocystis 6803.

Cyanobacteria↗
PubMed1999

Synthesis and in vitro activity of new oxazolidinone antibacterial agents having substituted isoxazoles.

Two series of oxazolidinone derivatives having substituted isoxazoles were synthesized and tested for antibacterial activities against several Gram-positive strains including the resistant strains of Staphylococcus and Enterococcus, such as MRSA, CRSA, MSSA and VRE. Some of them showed in vitro activities (MIC) comparable or superior to the reference compound vancomycin.

Anti-Bacterial Agents↗
PubMed1999

Synthesis and evaluation of 2 beta-oxyimino and alkenylpenicillanic acid sulfone derivatives as beta-lactamase inhibitors.

The synthesis and in vitro synergies of 2 beta-alkenyl and oxyiminopenam sulfone derivatives are described. Most of the compounds synthesized exhibited good inhibitory activities and synergistic antibacterial activities with piperacillin and ceftriaxone, respectively, against several beta-lactamase producing strains. Particularly the 2 beta-alkenylpenam sulfone derivatives. 1e and 1g, showed good synergistic activity with ceftriaxone against Citrobacter freundi NIH 10018-68 and Proteus vulgaris 20. Also the compounds 2a, 2c, and 2f, 2 beta-oxyiminopenam sulfone derivatives, exhibited improved synergistic activity with piperacillin against Citrobacter freundi NIH 10018-68.

Ceftriaxone↗
PubMed1999

Quality of life in Korean patients with inflammatory bowel diseases: ulcerative colitis, Crohn's disease and intestinal Behçet's disease.

Health-related quality of life (HRQOL) is an important outcome factor in chronic diseases such as inflammatory bowel disease (IBD). This study used the Korean translation of the disease-specific, self-administered Inflammatory Bowel Disease Questionnaire (IBDQ) to compare HRQOL in ulcerative colitis (UC; n = 98), Crohn's disease (CD; n = 49), and intestinal Behçet's disease (BD; n = 34). In addition to the current status, patients were asked retrospectively to recall their symptoms at the beginning and during the worst period of their disease. Disease activity was measured by St. Mark's Activity Index, Crohn's disease Activity Index (CDAI), and the Harvey-Bradshaw Index (HBI). In all IBD patients, including those with BD, the IBDQ total score during the worst period was significantly lower than that at present and that at the beginning of the disease. However, there were no significant differences between groups regarding the total IBDQ score or its various dimensions. In UC a strong correlation between IBDQ scores and St. Mark's Activity Index was observed (r = -0.708, P < 0.001). IBDQ scores were also highly correlated with CDAI and HBI in both CD (r = -0.506, P < 0.001 for CDAI; r = -0.600, P < 0.001 for HBI) and BD (r = -0.687, P < 0.001 for CDAI; r = -0.531, P < 0.001 for HBI). However, the current IBDQ score was not related to demographic parameters such as gender, age, educational status, economic status, and marital status as well as disease factors such as duration of disease, history of operation or hospital admission, extent of disease in UC, involved region in CD, and clinical type in BD. We conclude that the Korean IBDQ is a responsive and promising instrument for measuring HRQOL of IBD patients in clinical trials. In addition, the IBDQ can be helpful in developing a disease-specific activity index in BD.

Adolescent↗
PubMed1999

DNA-induced conformational change of Gaf1, a novel GATA factor in Schizosaccharomyces pombe.

A novel GATA factor in Schizosaccharomyces pombe, Gaf1, containing one zinc-finger motif was studied for conformational change that was induced by DNA-binding. Gaf1 was shown to bind to the upstream activation sequence of a gene in Saccharomyces cerevisiae containing GATA element by gel mobility shift assay. Circular dichroism spectra of Gaf1 indicated an increase of alpha-helix content of Gaf1 occurred upon binding to the upstream activation sequence. These results suggest that the binding of Gaf1 to the GATA element is required for the conformational change that may precede transactivation of the target gene(s).

Amino Acid Sequence↗
PubMed1999

Transluminal angioplasty for middle cerebral artery stenosis in patients with acute ischemic stroke.

BACKGROUND AND PURPOSE: Precutaneous transluminal angioplasty (PTA) is currently performed to treat supraaortic atherosclerotic lesions. Our purpose was to evaluate the safety and efficacy of PTA for middle cerebral artery (MCA) stenosis in patients with acute ischemic stroke. METHODS: We performed PTA with the use of a microballoon (2-2.5 mm in diameter and 10-13 mm in length) in 10 consecutive patients (mean age, 48 years) who met the following criteria: high-grade M1 stenosis (> 70%) and mild neurologic deficits (NIH stroke scale < 4) and/or recurrent transient ischemic attacks (TIAs) resistant to anticoagulation, or a large area of hypoperfusion in the MCA territory on brain perfusion SPECT scans. During follow-up, we administered antiplatelet agents and evaluated the status of restenosis by angiography (n = 2), brain perfusion SPECT (n = 4), and/or transcranial Doppler sonography (TCD) (n = 7). RESULTS: Stenotic arteries were successfully dilated in nine of 10 patients. Angioplasty failed in one patient because the balloon could not pass through the tortuous cavernous internal carotid artery. None of the patients experienced either peri- or postangioplasty complications. Residual stenosis was less than 50%, and clinical improvement, including elimination of TIAs in four patients who had suffered resistant TIAs, was observed in all patients; improvement of the cerebral perfusion was also noted in two patients with a large hypoperfusion area in the MCA territory. The average follow-up period was 11 months (range, 2 to 36 months). None experienced recurrent stroke during the follow-up period. TCD revealed decreased flow velocity of the MCA after angioplasty in seven patients. CONCLUSION: PTA of the proximal portion of the MCA seems to be a safe and effective therapeutic technique for the prevention of secondary ischemic stroke.

Acute Disease↗
PubMed1998

Inhibitory effect of hemin on mutagenicity of the electrophilic sulfuric acid ester of 6-hydroxymethylbenzo[a]pyrene.

In the present study, we examined the effects of hemin on the mutagenicity of 6-sulfooxymethylbenzo[a]pyrene (SMBP) in Salmonella typhimurium TA98 and Chinese hamster lung fibroblast (V79) cells. The compound was tested for the possible chemoprotective activity against mutagenesis induced by SMBP and its precursor, 6-hydroxymethylbenzo[a]pyrene (HMBP), activated by hepatic cytosol and PAPS in S. typhimurium TA98. Hemin not only inhibited the mutagenic activity of SMBP in V79 cells but repressed the cytotoxicity induced by this reactive ester as demonstrated by increased cell growth. The intracellular accumulation of radioactivity in V79 cells exposed to [3H]SMBP was reduced by approximately 50% when hemin (10 microM) was added to the medium. Likewise, the formation of SMBP-DNA adducts in these cells was significantly attenuated by treatment with hemin. The covalent complex formation of hemin with SMBP was confirmed by solvent extraction and reverse-phase HPLC.

Animals↗
PubMed1998

Mutagenicity of 6-sulfooxymethylbenzo[a]pyrene in Salmonella typhimurium and Chinese hamster V79 cells.

6-Sulfooxymethylbenzo[a]pyrene (SMBP) is an ultimate and reactive form of 6-hydroxymethybenzo[a]pyrene (HMBP), which is converted into SMBP by the mediation of sulfotransferase. SMBP and HMBP with metabolic activation were mutagenic to S. typhimurium TA98 and TA100. The number of mutation per plate in strain TA98 was proportional to the concentrations of SMBP ranging from 0.2 to 1.0 nmol/plate, whereas that in strain TA100 was decreased at concentrations above 0.6 nmol/plate. The mutation frequencies by HMBP was also increased in a dose dependent manner in both strains. Furthermore, SMBP and HMBP were highly mutagenic and cytotoxic to Chinese hamster lung fibroblast (V79) cells. A dose-dependent increase in mutation frequencies at both hypoxanthine:guanine phosphoribosyltransferase (HGPRT) and sodium/potassium-ATPase (Na/K-ATPase) loci were found in V79 cells treated with SMBP and HMBP. The cytotoxicity of SMBP was increased with the increasing concentrations up to 2.5 microM, where the survival frequency and growth rate were decreased to almost 40% and 30% of the control value, respectively. The survival frequencies of V79 cells by HMBP were also decreased in a dose dependent manner up to 180 microM as similar to those of SMBP but the effects were less remarkable. SMBP was progressively accumulated in V79 cells, reaching plateau in just 30 min. A dose dependent increase in complex formation with DNA or proteins was observed by treatment with SMBP. The mutagenicity and cytotoxicity of SMBP and HMBP may be derived from their binding capacity to DNA in V79 cells and S. typhimurium.

Animals↗
PubMed1998

Auto-ADP-ribosylation of NAD glycohydrolase from Neurospora crassa.

NAD glycohydrolase (NADase; EC 3.2.2.5) is an enzyme that catalyzes hydrolysis of NAD to produce ADP-ribose and nicotinamide. We recently demonstrated that self-inactivation of NADase from rabbit erythrocytes was due to an auto-ADP-ribosylation. In the present study, a mechanism of self-inactivation of NADase from Neurospora crassa by its substrate was investigated by using intact mycelia of N. crassa and purified NADase, which had molecular characteristics different from mammalian NADases. The results suggested that inactivation of NADase from N. crassa was also due to an auto-ADP-ribosylation. These findings indicate that the auto-modification of NADase is one of the universal phenomena to regulate enzyme functions.

Adenosine Diphosphate Ribose↗
PubMed1998

Phospholipase Cgamma1 inhibitory principles from the sarcotestas of Ginkgo biloba.

Ten phenolic compounds were isolated from the CHCl3 extract of Ginkgo biloba sarcotestas (Ginkgoaceae) as a new class of phosphatidylinositol-specific phospholipase Cgamma1 (PI-PLCgamma1) inhibitors. The substances without the long chain were ineffective. On the other hand, the activities of these compounds were dramatically decreased by acetylation of aromatic hydroxyl groups of cardanol, phenolic acid, and bilobol and by methylation of the aromatic carboxyl group of phenolic acid. The unsaturated long chain as well as the aromatic hydroxyl and carboxyl groups might play a key role for the PI-PLCgamma1 inhibitory activity. These compounds also inhibited the growth of a number of human cancer cell lines, but were less cytotoxic against a human normal colon cell line.

Cells, Cultured↗