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Biomedical subjects

D S Choi

Publications and source records attributed to D S Choi.

At least 19 recordsLinked to original sources
PubMed2003

Relation between insulin resistance and hematological parameters in elderly Koreans-Southwest Seoul (SWS) Study.

In this study, we investigated the relation between insulin resistance and hematological parameters in elderly Koreans. This study included 1314 non-diabetic subjects over the age of 60, selected from a cross-sectional study, which was conducted in 1999 in Seoul, Korea. We measured fasting and post-load 2 h plasma glucose, insulin levels, lipid profiles, anthropometric measures, and hematological parameters. The degree of insulin resistance was assessed using the homeostasis model assessment (HOMA). We found a correlation between insulin resistance and hemoglobin concentrations in non-smoking men (r=0.20, P=0.0186). In non-smoking women, insulin resistance correlated with hemoglobin (r=0.10, P=0.0017) and with white blood cell (WBC) count (r=0.15, P=0.001). Hemoglobin concentrations and WBC counts were also associated with other components of the insulin resistance syndrome such as body mass index, blood pressure, lipid profiles and fasting plasma insulin levels (surrogate for insulin resistance). Furthermore, the group in the upper quartile for insulin resistance showed higher hemoglobin concentrations and WBC counts than the lower quartile, independent of smoking status and serum iron concentrations. Using HOMA-IR as a dependent variable in a multiple regression analysis, age, body mass index (BMI), waist-to-hip ratio (WHR), systolic blood pressure, HDL cholesterol, triglyceride, WBC count, hemoglobin, hematocrit and serum TIBC were significant. Our results provide support for a relation between insulin resistance/hyperinsulinemia and hematological parameters such as hemoglobin concentrations and WBC counts in elderly Koreans. This suggests that increased erythropoiesis and subclinical inflammation could be part of the metabolic syndrome in elderly Koreans.

Aged↗
PubMed2003

Factor analysis of the metabolic syndrome among elderly Koreans--the South-west Seoul Study.

AIMS: To examine the relationship between the components of the metabolic syndrome and to explore whether insulin resistance unifies the clustering of components of the metabolic syndrome among urban elderly Koreans using exploratory factor analysis. METHODS: We included 1314 non-diabetic subjects over the age of 60 years, selected from a cross-sectional study, which was conducted in 1999 in Seoul, Korea. Factor analysis was carried out using the principle components analysis with Varimax orthogonal rotation of the components of the metabolic syndrome. RESULTS: We found four major factors of cardiovascular disease risk variables in our study subjects. Impaired glucose tolerance, dyslipidaemia, hypertension and obesity aggregated as the major domain. Obesity and dyslipidaemia variables were closely related and loaded on the same factor. However, hypertension was not linked closely with other factors of the metabolic syndrome. CONCLUSIONS: Insulin resistance is not the only contributor to the metabolic syndrome among urban elderly Koreans. Although the components of the metabolic syndrome were closely related, the finding of more than one factor suggests that more than one pathophysiological mechanism underlies full expression of the metabolic syndrome among elderly Koreans.

Aged↗
PubMed2002

Comparison of ADA and WHO criteria for the diagnosis of diabetes in elderly Koreans.

AIMS: This study was conducted to compare the prevalence and cardiovascular risk factors of different categories of glucose tolerance in the elderly Korean population using World Health Organization (WHO) and American Diabetes Association (ADA) criteria. METHODS: This study included 1456 non-diabetic subjects over the age of 60 years, selected from a cross-sectional study, which was conducted in 1999 in Seoul, Korea. Fasting and post-challenge 2-h plasma glucose, insulin levels, body mass index (BMI), waist-hip ratio (WHR), blood pressure, and lipid profiles were examined. Prevalence of glucose tolerance categories and the level of agreement (kappa statistics) were obtained using WHO 2-h criteria and ADA fasting criteria. Comparison of cardiovascular risk factors among several concordant and discordant glucose intolerance groups was done. RESULTS: The prevalence rates of newly diagnosed diabetes of elderly men defined by WHO 2-h criteria and ADA fasting criteria were 11.8% and 4.8%, respectively. That of elderly women was 8.1% by WHO 2-h criteria and 3.1% by ADA fasting criteria. The prevalence of impaired glucose tolerance (IGT) by WHO criteria was also higher than that of impaired fasting glucose (IFG) by ADA criteria (23.5% vs. 10.0% men, 23.7% vs. 7.5% women). The level of agreement between ADA fasting criteria and WHO 2-h criteria was low (weighted kappa = 0.228 men, weighted kappa = 0.301 women). The concordant diabetic women by both ADA fasting criteria and WHO 2-h criteria showed higher BMI, WHR, diastolic blood pressure, total cholesterol and triglyceride levels than concordant normal subjects. However, the isolated post-challenge hyperglycaemia (IPH) women group was not different significantly from the concordant normal women group except in BMI. CONCLUSIONS: Our results clearly show that the 1997 ADA fasting criteria are less sensitive for diagnosing diabetes than oral glucose tolerance test (OGTT)-based WHO criteria in elderly Koreans. Also, there is a poor agreement of different categories of glucose tolerance between ADA and WHO criteria; therefore, the OGTT remains a valuable test in diagnosing diabetes and classifying various categories of glucose intolerance, especially in elderly Koreans.

Aged↗
PubMed2001

Molecules with shape memory based on restricted rotation.

[reaction--see text] Diimide 1 and octaimide 2 both adopt two stable conformations at room temperature as a result of restricted rotation about two C(aryl)-N(imide) single bonds, a compact "folded" and an open "unfolded" structure. Predictable ratios of folded and unfolded rotamers can be achieved by heating in solvents of appropriate polarity as measured by the Reichardt's parameter (E(T30)). On cooling to room temperature, the resulting conformational changes are "locked in" as restricted rotation is reestablished.

Journal Article↗
PubMed2001

Cloning of a novel isoform of the mouse NBMPR-sensitive equilibrative nucleoside transporter (ENT1) lacking a putative phosphorylation site.

We have isolated a mouse cDNA clone corresponding to a novel isoform of the NBMPR-sensitive equilibrative nucleoside transporter (ENT1). The cDNA contains a 6 bp deletion in the open reading frame that changes the amino acid composition in a consensus casein kinase II (CKII) phosphorylation site at Ser-254. The clone containing Ser-254 is termed mENT1.1 and the clone lacking the serine termed mENT1.2. The deduced amino acid sequence of mENT1.1 corresponds to the previously cloned human and rat ENT1 proteins at Ser-254. Tissue distribution studies show that mRNA for both ENT1 isoforms are ubiquitously co-expressed in mouse. Analysis of genomic DNA corresponding to mouse ENT1 indicates the isoforms can be produced by alternative splicing at the end of exon 7. CEM/C19 cells stably expressing mENT1.1 and mENT1.2 show similar dose response curves for NBMPR and dipyridamole inhibition of [(3)H]adenosine uptake as well as exhibiting comparable selectivity for both purine and pyrimidine nucleosides but not the corresponding nucleobases.

Amino Acid Sequence↗
PubMed2001

Localization of matrix metalloproteinases on endometrial cancer cell invasion in vitro.

OBJECTIVES: In this study, we have established an in vitro three-dimensional (3D) coculture, where normal endometrial stromal cells and endometrial cancer cells were cocultured under defined hormonal conditions, to investigate the potential paracrine effects on synthesis and secretion of matrix metalloproteinases (MMPs) and, thus, cancer invasion. METHODS: Endometrial stromal cells were obtained by biopsy, cultured in the presence of 100 nM estrogen for 3 days, and then mixed with extracellular matrix (ECM) composed of collagen I and matrigel in a 4:1 ratio. After 3 more days in culture, a 3D coculture was established with HEC-1A cells, an endometrial adenocarcinoma cell line, grown on top of the mixture under various ovarian steroids (no steroid, 100 nM beta-estradiol (E2), or 1.0 microM progesterone (P4)) for 10 days. The expression and localization of MMP-2, MMP-9, and integrin beta 3 subunit were visualized by immunocytochemistry and analyzed by reverse transcription polymerase chain reaction (RT-PCR). The extent of cancer invasion was quantified by Boyden's chamber assay. RESULTS: Integrin beta 3 subunit was localized along the cell surface of HEC-1A cell under all three hormonal conditions. MMP-2 was located in the cytoplasm of stromal cells and on the surface of HEC-1A cells. Synthesis and secretion of stromal MMP-2 were increased in the presence of ovarian steroids. In contrast, expression of stromal MMP-9 was suppressed in the presence of ovarian steroids. No MMPs were synthesized in HEC-1A cells. Invasion assay revealed that HEC-1A cells achieved high tumoral invasiveness in the presence of beta-estradiol. CONCLUSIONS: These findings suggest that stromal cell-derived MMP-2 is translocated to the surface of HEC-1A cells. Integrin beta 3 subunit might contribute, in part, to providing a binding site for MMP-2. Thus, HEC-1A cells invade by recruiting MMP-2 secreted by stromal cells, which is greatly enhanced in the presence of beta-estradiol. The 3D coculture provides an excellent experimental system in which single parameters can be isolated from a complex in vivo system in the process of endometrial cancer invasion.

Adenocarcinoma↗
PubMed2001

Investigation of juxtasellar and cerebellopontine angle meningiomas and neurogenic tumours: two-phase helical CT.

We performed two-phase helical CT in 31 patients with juxtasellar region and cerebellopontine angle tumours to evaluate its usefulness in differentiating meningiomas from neurogenic tumours. After the intravenous injection of 90 ml contrast medium at 3 ml/s, axial helical images were obtained with delays of 30 and 120 s. After the delayed axial images, we acquired coronal images. Changes in attenuation were assessed visually and quantitatively (by comparing the attenuation in Hounsfield units). There were 17 meningiomas and 14 neurogenic tumours, all pathologically proven. Two-phase helical CT showed a decrease in attenuation in 15 (88%) meningiomas and an increase in 14 (100%) neurogenic tumours from early to delayed axial images. Coronal images showed a decrease in attenuation in all 17 meningiomas and an increase in 13 (93%) of the neurogenic tumours. The mean HU and their ratios were significantly different between meningiomas and neurogenic tumours.

Adult↗
PubMed2001

Transgenic and gene "knockout" models in alcohol research.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Paula L. Hoffman and Takeshi Yagi. The presentations were (1) cAMP signaling in ethanol sensitivity and tolerance, by Boris Tabakoff; (2) Synaptic signaling pathways of Fyn-tyrosine kinase, by Takeshi Yagi; (3) Ethanol drinking and sensitization in dopaminergic and serotonergic receptor knockouts, by Tamara J. Phillips; (4) ICAM-1 is involved in early alcohol-induced liver injury in the mouse given enteral alcohol, by Hiroshi Kono; and (5) Strategies for targeted and regulated knockouts, by Robert O. Messing and Doo-Sup Choi.

Adenylyl Cyclases↗
PubMed2001

Inhibitory activity of berberine on DNA strand cleavage induced by hydrogen peroxide and cytochrome c.

The inhibitory activity of berberine on the DNA single-strand cleavage induced by hydrogen peroxide and cytochrome c was measured. Berberine effectively inhibited single-strand cleavage of DNA and its effectiveness was concentration-dependent. As the berberine concentration increased, the inhibitory activity against the DNA single-strand cleavage increased. The treatments with 1, 5, 10, 50, and 100 microM berberine showed 7.7, 10.8, 32.2, 39.5, and 51.6% inhibition of DNA cleavage. This inhibitory activity of berberine against the DNA single-strand cleavage has never been reported previously. The inhibitory activity of berberine against DNA cleavage was stronger than caffeic acid and ascorbic acid. Berberine did not show strong hydroxyl radical scavenging activity, but showed strong superoxide anion radical quenching ability.

Antioxidants↗
PubMed2001

A case of adrenocortical tumor coexisted with paragangliomas.

We report a case of adrenocortical tumor that coexisted with paragangliomas. A 35-year-old woman was admitted to the hospital because of left upper abdominal pain. A palm-sized mass was palpated at left upper quadrant. Hormonal studies revealed the features of pheochromocytoma. An emergency operation was performed because hemorrhage of the tumor was suspected. A 10 cm diameter ruptured mass was found in the left adrenal area and other tumors were also noted adjacent to inferior vena cava (IVC). The pathologic report revealed that the adrenal mass was an adrenocortical tumor with hemorrhagic necrosis and that the tumors adjacent to IVC were paragangliomas. This was the first case of adrenocortical tumor with paragangliomas in our Medline search result, hence we report the case with a review of the literature.

Adrenal Cortex Neoplasms↗
PubMed2001

Fra-1 expression in malignant and benign thyroid tumor.

BACKGROUND: The differential diagnosis of thyroid nodules is very important in deciding the treatment modality and the fine needle aspiration is the best diagnostic method. But, there are some limitations in use because of inadequate test materials and difficulty in interpreting. According to the study of oncogene and tumor suppressor gene about the origin of thyroid tumor, expression of Fra-1, one of AP-1 complex, is increased in thyroid neoplasm, though not present in the normal tissue. So, there is a possibility that it will be used as a method for the differential diagnosis of thyroid nodules. We tried to know whether presence or absence of Fra-1 expression can be used as a diagnostic method in differential diagnosis of thyroid nodules using the immunohistochemical (IHC) staining method. METHODS: In 4 types of thyroid tumor that were confirmed by histologic diagnosis after operation (18 cases of adenomatous goiter, 16 cases of follicular adenoma, 30 cases of papillary cancer, 10 cases of follicular cancer), IHC staining method was performed to evaluate the expression of Fra-1. RESULTS: In papillary and follicular thyroid cancers, the expression of Fra-1 was stronger than in benign thyroid tumor, but there was no difference in Fra-1 expression between the two types of carcinoma. Weak expression of Fra-1 was observed in all cases of follicular adenoma, though it was weaker than in carcinoma, and it was also weakly expressed only in some cases (33%) of adenomatous goiter. CONCLUSION: The expression of Fra-1 was stronger in thyroid cancer than in benign thyroid tumor, but it was impossible to differentiate thyroid cancer from benign thyroid tumor by presence or absence of Fra-1 expression using IHC staining method.

Biomarkers, Tumor↗
PubMed2000

Genomic organization and expression of the mouse equilibrative, nitrobenzylthioinosine-sensitive nucleoside transporter 1 (ENT1) gene.

We have cloned and characterized the genomic structure of the mouse gene for the NBMPR-sensitive equilibrative nucleoside transporter (mENT1), which is located on chromosome 17C. About 12-kb of genomic DNA was sequenced including the promoter region, 12 exons, 11 introns, and the 3'-untranslated region. All exon-intron junction sequences conform to the GT/AG rule. Primer extension analysis demonstrated a transcription initiation site located 252 bp upstream of the translation start site. Analysis of the 2.5-kb 5'-flanking sequence shows putative binding sites for several transcription factors, including GATA-1, IRF-2, Pit-1, myogenin, CREB, Sp-1, Ap-2, MAZ, and GR. We demonstrated that mouse ENT1 mRNA was highly expressed in heart, spleen, lung, liver, and testis. Lower levels of expression were detected in brain and kidney. Functional analysis of the 5'-flanking region showed that the nucleotide sequence from -652 to -111 contains cis-regulatory elements that promote gene expression. We found two Sp-1 binding sites (-296/-303, -307/-313) and two MAZ binding sites (-353/-359, -522/-528) in this region. Luciferase assay results suggest that MAZ and Sp-1 transcription factors are important positive regulators of transcription for the ENT1 gene in NG108-15 cells.

3' Untranslated Regions↗
PubMed2000

Serotonin 2B receptor is required for heart development.

Several lines of evidence suggest that the serotonin (5-hydroxytryptamine, 5-HT) regulates cardiovascular functions during embryogenesis and adulthood. 5-HT binds to numerous cognate receptors to initiate its biological effects. However, none of the 5-HT receptor disruptions in mice have yet resulted in embryonic defects. Here we show that 5-HT(2B) receptor is an important regulator of cardiac development. We found that inactivation of 5-HT(2B) gene leads to embryonic and neonatal death caused by heart defects. 5-HT(2B) mutant embryos exhibit a lack of trabeculae in the heart and a specific reduction in the expression levels of a tyrosine kinase receptor, ErbB-2, leading to midgestation lethality. These in vivo data suggest that the Gq-coupled receptor 5-HT(2B) uses the signaling pathway of tyrosine kinase receptor ErbB-2 for cardiac differentiation. All surviving newborn mice display a severe ventricular hypoplasia caused by impaired proliferative capacity of myocytes. In adult mutant mice, cardiac histopathological changes including myocyte disarray and ventricular dilation were consistently observed. Our results constitute genetic evidence that 5-HT via 5-HT(2B) receptor regulates differentiation and proliferation of developing and adult heart. This mutation provides a genetic model for cardiopathy and should facilitate studies of both the pathogenesis and therapy of cardiac disorders in humans.

Animals↗
PubMed2000

Basal signaling activity of human dopamine D2L receptor demonstrated with an ecdysone-inducible mammalian expression system.

Basal signaling activity of the dopamine D2L (long isoform) receptor was investigated using an ecdysone-inducible mammalian expression system. Whereas basal signaling activity had been demonstrated for the D1, D2S (short isoform), D3, and D5 receptor subtypes, this issue has yet to be clearly resolved for the D2L receptors. An ecdysone-inducible mammalian expression system was used to express the dopamine D2L receptor in human embryonic kidney cells (HEK293). The two ecdysone analogs, muristerone A and ponasterone A, induced D2L receptor expression dose-dependently from 120 (non-induced) to 2000 fmol/mg protein which is similar to physiological D2 receptor density in dopaminergic brain regions. With this approach, we demonstrate significant basal D2L receptor activity. Basal and agonist-stimulated signaling activity, determined with assays of cAMP levels and [35S]GTPgammaS binding to assess G protein coupling, correlated with the level of receptor expression. Furthermore, among several antagonists tested, only fluphenazine and trifluoperazine exhibited clearly detectable inverse agonist activity. This differs from the D2S receptors, where most antagonists were reported to display full inverse agonism. Differences between inverse agonist effects of D2L and D2S antagonists may be relevant to the treatment of diseases involving dopamine D2 receptors.

Cell Line↗
PubMed2000

Salivary gland tumors: evaluation with two-phase helical CT.

PURPOSE: To evaluate two-phase helical computed tomography (CT) in the characterization of salivary gland tumors. MATERIALS AND METHODS: Sixty-four patients with major salivary gland tumors underwent two-phase helical CT. The histopathologic diagnosis was obtained by means of surgical resection or biopsy in all patients. After the injection of 90 mL of contrast material at a rate of 3 mL/sec, helical CT scans were obtained at early and delayed phases with scanning delays of 30 and 120 seconds, respectively. The attenuation change and enhancement patterns in the tumors were assessed. The attenuation change in the tumor also was assessed quantitatively as the ratio of the CT number (in Hounsfield units) at delayed phase scanning to that at early phase scanning. RESULTS: There were 35 pleomorphic adenomas, nine Warthin tumors, and 20 malignant tumors. Two-phase helical CT showed increase in attenuation in 30 (86%) pleomorphic adenomas, decrease in eight (89%) Warthin tumors, and increase in 11 (55%) and no change in eight (40%) malignant tumors at delayed phase scanning. A multinodular enhancement pattern was found in only 12 (34%) pleomorphic adenomas. The ratio of CT numbers was significantly different between Warthin tumors and pleomorphic adenomas and between Warthin tumors and malignant tumors. CONCLUSION: The analysis of enhancement patterns by using two-phase helical CT will be helpful in the differential diagnosis of salivary gland tumors.

Adolescent↗
PubMed2000

Expression of vascular endothelial growth factor in response to high glucose in rat mesangial cells.

Diabetic nephropathy associated with hyperglycemia is characterized by glomerular hyperfiltration and endothelial dysfunction. Vascular endothelial growth factor (VEGF) is known to be primarily involved in neoangiogenesis and increased endothelial permeability. The purpose of this study was to investigate VEGF expression in response to high glucose in rat cultured mesangial cells and to identify its signal pathway via protein kinase C (PKC). Rat mesangial cells were cultured with different concentrations of glucose: normal (5 mM d-glucose), medium (15 mM d-glucose) and high (30 mm d-glucose). Calphostin-C as a PKC inhibitor and phorbol myristate acetate (PMA) as a PKC downregulator were instillated into culture media to evaluate the role of PKC in mediating the glucose-induced increase in VEGF expression. High glucose increased expression of VEGF at the mRNA and protein levels, identified by semi-quantitative RT-PCR and western blotting, within 3 h and in a time- and glucose concentration-dependent manner. Calphostin-C and PMA inhibited glucose-induced increases in VEGF expression at the mRNA and protein levels. In conclusion, high glucose can directly increase VEGF expression in rat mesangial cells via a PKC-dependent mechanism. These results suggest that VEGF could be a potential mediator of glomerular hyperfiltration and proteinuria in diabetic nephropathy.

Animals↗
PubMed2000

Changes in biochemical bone markers during pregnancy and puerperium.

To elucidate the changes in bone turnover during pregnancy and puerperium, we measured serially the levels of serum osteocalcin and urine deoxypyridinoline (Dpy) as markers of bone formation and bone resorption, respectively, in 22 healthy women with normal pregnancy. Nineteen non-pregnant women served as control. The Dpy levels increased significantly at 16 weeks of pregnancy and remained elevated thereafter. The levels of osteocalcin, however, were significantly decreased at 16 weeks of pregnancy and elevated later at 6 weeks postpartum. Bone turnover ratio (Dpy/osteocalcin) continued to rise during pregnancy, but returned to control levels 6 weeks after delivery. Dpy levels and bone turnover ratio during puerperium tended to be higher in 17 breast-feeding women than those of 5 exclusive bottle-feeders. In conclusion, bone resorption begins to increase from the second trimester of pregnancy and calcium release from bone tissue might play a major role in calcium homeostasis during the whole period of pregnancy as well as during lactation.

Adult↗