Biomedical subjects

Dong-Hyun Kim

Publications and source records attributed to Dong-Hyun Kim.

At least 19 recordsLinked to original sources

PubMed2007

Validation and application of a screening method for beta2-agonists, anti-estrogenic substances and mesocarb in human urine using liquid chromatography/tandem mass spectrometry.

Electrospray ionization (ESI) mass spectra of 15 anti-estrogenic substances, beta2-agonists and mesocarb were investigated in terms of fragmentation patterns. On the basis of this product ion information, a simultaneous screening method for anti-estrogenic substances, beta2-agonists and mesocarb was developed for doping control purposes. After hydrolysis, liquid-liquid extraction was adopted for the sample preparation. The recoveries for all compounds were 30 and 96%. A single liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis could be performed in 13 min for the analysis of 15 anti-estrogenic substances, beta2-agonists and mesocarb. A quantitative analysis was also validated. Inaccuracies were below +/-12% and precisions varied from 0 to 15.8%. The limit of detection was below 10 ng/mL except formestane (300 ng/mL) and aminoglutethimide (100 ng/mL). The validated method was applied for the analysis of excretion samples.

Adrenergic beta-2 Receptor Agonists↗

PubMed2007

Cloning, expression and purification of arylsulfate sulfotransferase from Eubacterium A-44.

A gene (astA) encoding arylsulfate sulfotransferase (ASST), which transfers a sulfate group from phenolic sulfate esters to phenolic acceptors, was cloned from a Eubacterium A-44 genomic library. The probe (1.5 kb fragment) for the astA gene was prepared from the PCR product of the primers produced using two internal amino acid sequences of ASST, which had been purified from Eubacterium A-44. The astA gene was cloned into the pKF3 vector. Its sequence revealed a 1863 bp open reading frame (ORF) encoding a protein containing 620 amino acids with a secretary signal peptide, and showed 91% homology (identity) to Eubacterium rectale IIIH previously reported. The cloned astA gene was expressed under the T7 promoter of the expression vectors, pET-39b(+) and pET-26b(+), in Escherichia coli BL21 (DE3), and the expressed ASSTs were purified using His Bind column chromatography. The specific activities of the purified ASSTs were 25.6 micromol/min/mg and 37.1 micromol/min/mg, respectively.

Amino Acid Sequence↗

PubMed2007

In vitro and in vivo antiallergic effect of the fructus of Evodia rutaecarpa and its constituents.

The unripe fruit of Evodia rutaecarpa (JUSS) BENTH (ER, Family Rutaceae) has been used frequently as a traditional medicine against inflammatory diseases in Korea, China and Japan. To evaluate antiallergic effect of ER, we isolated its main constituents, evodiamine and rutaecarpine, and evaluated in vivo their inhibitory effects against passive cutaneous anaphylaxis (PCA) reaction induced by IgE-antigen complex and scratching behaviors by compound 48/80. ER and its constituents, evodiamine and rutaecarpine, potently inhibited PCA reaction and scratching behaviors in mice, although ER weakly inhibited scratching behaviors. Evodiamine and rutaecarpine inhibited TNF-alpha and IL-4 protein expression in RBL-2H3 cells induced by IgE-antigen complex, although these did not inhibit degranulation of RBL-2H3 cells induced by IgE-antigen complex and rat peritoneal mast cells induced by compound 48/80. These findings suggest that ER and its constituents, evodiamine and rutaecarpine, may be effective for IgE-induced allergic diseases such as atopic dermatitis and rhinitis.

Alkaloids↗

PubMed2006

Anti-inflammatory mechanisms of isoflavone metabolites in lipopolysaccharide-stimulated microglial cells.

The microglial activation plays an important role in neurodegenerative diseases by producing several proinflammatory cytokines and nitric oxide (NO). We found that three types of isoflavones and their metabolites that are transformed by the human intestinal microflora suppress lipopolysaccharide (LPS)-induced release of NO and tumor necrosis factor (TNF)-alpha in primary cultured microglia and BV2 microglial cell lines. The inhibitory effect of the isoflavone metabolites (aglycon form) was more potent than that of isoflavones (glycoside form). The RNase protection assay showed that the isoflavone metabolites regulated inducible nitric oxide synthase (iNOS) and the cytokines at either the transcriptional or post-transcriptional level. A further molecular mechanism study was performed for irisolidone, a metabolite of kakkalide, which had the most potent anti-inflammatory effect among the six isoflavones tested. Irisolidone significantly inhibited the DNA binding and transcriptional activity of nuclear factor (NF)-kappaB and activator protein-1. Moreover, it repressed the LPS-induced extracellular signal-regulated kinase (ERK) phosphorylation without affecting the activity of c-Jun N-terminal kinase or p38 mitogen-activated protein kinase. The level of NF-kappaB inhibition by irisolidone correlated with the level of iNOS, TNF-alpha, and interleukin (IL)-1beta suppression in LPS-stimulated microglia, whereas the level of ERK inhibition correlated with the level of TNF-alpha and IL-1beta repression. Overall, the repression of proinflammatory cytokines and iNOS gene expression in activated microglia by isoflavones such as irisolidone might have therapeutic potential for various neurodegenerative diseases including ischemic cerebral disease.

Animals↗

PubMed2006

Hinokiresinol inhibits IgE-induced mouse passive cutaneous anaphylaxis reaction.

The antiallergic effect of hinokiresinol isolated from the whole plant of TRAPA Pseudoincisa S. at. Z. was measured in vitro and in vivo. Hinokiresinol not only potently inhibited beta-hexosaminidase release from RBL-2H3 cells induced by IgE, with an IC50 value of 98 microM, but also inhibited the proinflammatory cytokines IL-6, IL-4 and TNF-alpha in RBL-2H3 cells stimulated by IgE. Orally and intraperitoneally administered hinokiresinol potently inhibited the passive anaphylaxis reaction in mice induced by IgE.

Administration, Oral↗

PubMed2006

A high nuclear basal level of ERK2 phosphorylation contributes to the resistance of cisplatin-resistant human ovarian cancer cells.

OBJECTIVE: The aim of this study was to elucidate the role of ERK1/2 on cisplatin resistance in human ovarian cancer cells. METHODS: The relationship between nuclear levels of ERK2 and cisplatin-induced apoptosis in human ovarian carcinoma cell line, OVCAR-3, and in cells of the cisplatin-resistant subclone, OVCAR-3/CDDP, was examined using immunoblotting and immunocytochemistry. RESULTS: Cisplatin treatment resulted in the activation of ERK2, both in OVCAR-3 and OVCAR-3/CDDP cells. However, considerable levels of activated ERK2 existed in the nuclei of OVCAR-3/CDDP cells during serum starvation and in the early period (1-3 h) after cisplatin treatment. Conversely, phospho-ERK2 was marginally detected in the nuclei of OVCAR-3 cells prior to cisplatin treatment. These phenomena were confirmed by immunofluorescence staining of the phosphorylated ERK2 in the nuclei of both cells. High basal phospho-ERK2 in the nuclei of OVCAR-3/CDDP cells contributed to cisplatin resistance, and was supported by several observations; (1) treatment of U0126, an inhibitor of MEK/ERK signaling pathway, partially sensitized OVCAR-3/CDDP cells to cisplatin; (2) pretreatment of OVCAR-3 cells with phorbol 12-myristate 13-acetate (PMA), an activator of ERK, induced nuclear translocation of activated ERK2, which led to the suppression of cisplatin-induced apoptosis. CONCLUSIONS: These results collectively indicate that prelocalization of activated ERK2 in the nuclei contribute to cisplatin resistance in OVCAR-3/CDDP cells.

Antineoplastic Agents↗

PubMed2006

Liquid chromatography-tandem mass spectrometric determination of ceramides and related lipid species in cellular extracts.

A liquid chromatography-electrospray ionization tandem mass spectrometric (LC-MS/MS) method was developed for the simultaneous qualitative and quantitative determination of sphingolipid metabolites such as ceramides, sphingisine, sphinganine, sphingomyelins, and ceramide 1-phosphates in the extracts of human promyelocytic leukemia cells (HL-60). The assay uses C(4) ceramide as an internal standard; simple liquid extraction; a short XTerra MS C(18) (3 microm, 50 mm x2.0 mm) column; a gradient mobile phase of 5mM ammonium formate (pH 4.0)/methanol/tetrahydrofuran (5/2/3-->1/2/7); mass spectrometric detection using electrospray ionization. This LC-MS/MS method allowed the identification of 22 sphingolipid derivatives at pmol levels. In addition, this technique was successfully applied to analyze the changes of the sphingolipids profiles in cancer cells treated with apoptosis inducing agents, C(2) ceramide and H(2)O(2).

Apoptosis↗

PubMed2006

8-hydroxydeoxyguanosine suppresses NO production and COX-2 activity via Rac1/STATs signaling in LPS-induced brain microglia.

Free 8-hydroxydeoxyguanosine (oh(8)dG), a nucleoside of 8-hydroxyguanine (oh(8)Gua), present in cytosol is not incorporated into DNA. However, nothing is known about its biological function when it presents in cytosol as a free form. We demonstrate here for the first time that oh(8)dG inhibits lipopolysaccharide (LPS)-induced nitric oxide (NO) production and cyclooxygenase-2 (COX-2) activity, and both gene transcriptions in microglia. Furthermore, oh(8)dG reduced mRNA levels of pro-inflammatory cytokine, such as IL-1beta, IL-6, and TNF-alpha, in activated BV2 cells. We also found that oh(8)dG suppressed reactive oxygen species (ROS) production through reduction of NADPH oxidase activity and blocked Rac1/STATs signal cascade. Finally, oh(8)dG suppressed recruitment of STATs and p300 to the iNOS and COX-2 promoters, and inhibited H3 histone acetylation. Taken together, these results provide new aspects of oh(8)dG as an anti-inflammatory agent.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2006

Irisolidone, an isoflavone metabolite, represses JC virus gene expression via inhibition of Sp1 binding in human glial cells.

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease that results from an oligodendrocyte infection caused by the JC virus. Therefore, inhibiting the expression of JC virus is important for preventing and/or treating PML. This study found that irisolidone, an isoflavone metabolite, significantly inhibited the JC virus expression in primary cultured human astrocytes and glial cell lines. Studies examining the underlying mechanism revealed that a mutation of the Sp1 binding site downstream of the TATA box (Sp1-II) dramatically diminished the inhibitory activity of irisolidone. In addition, an irisolidone treatment repressed Sp1 binding to Sp1-II site, which is important for the basal JC virus promoter activity. The results suggest that the inhibitory effect of irisolidone against the JC virus may be attributed at least in part to the suppression of Sp1 binding to the JC virus promoter region. Therefore, the inhibition of the JC virus expression by irisolidone might provide therapeutic potential for PML caused by the JC virus.

Base Sequence↗

PubMed2006

Ginsenosides Rg3 and Rh2 inhibit the activation of AP-1 and protein kinase A pathway in lipopolysaccharide/interferon-gamma-stimulated BV-2 microglial cells.

The anti-inflammatory effect of ginsenosides Rg3 and Rh2, which improves ischemic brain injury induced by middle cerebral artery occlusion, was investigated in lipopolysaccharide (LPS) and IFN-gamma-induced murine BV-2 microglial cells. Ginsenoside Rh2 inhibited the production of NO, with an IC50 value of 17 microM. The inhibitory effect of Rh2 on NO correlates with the decreased protein and mRNA expression of an inducible NO synthase (iNOS) gene. Additionally, ginsenoside Rh2 inhibited the expression of COX-2, pro-inflammatory TNF-alpha and IL-1beta in BV-2 cells induced by LPS/IFN-gamma, while it increased the expression of the anti-inflammatory cytokine IL-10. Electrophoretic mobility shift assays revealed that ginsenoside Rh2 significantly inhibited the LPS/IFN-gamma-induced AP-1 DNA binding activity, while it enhanced the protein binding to CRE sequences. However, it did not affect NF-kappaB binding activity. Thus, the anti-inflammatory effect of Rh2 appears to depend on the AP-1 and protein kinase A (PKA) pathway. The anti-inflammatory effect of ginsenoside Rg3 against LPS/IFN-gamma-activated BV-2 cells was less potent than that of ginsenoside Rh2. These findings suggest that the in vivo anti-ischemic effect of ginsenoside Rg3 may originate from ginsenoside Rh2, which is a main metabolite of ginsenoside Rg3 by intestinal microflora, and that of ginsenoside Rh2 may be due to its anti-inflammatory effect in brain microglia.

Animals↗

PubMed2006

20(S)-ginsenoside Rh2, a newly identified active ingredient of ginseng, inhibits NMDA receptors in cultured rat hippocampal neurons.

Most herbal medicines that are orally administrated have been known to be metabolized before they are absorbed from the gastrointestinal tract. We, therefore, examined the effects of 20(S)-ginsenosides Rb1, Rg1 and Rg3, the three most commonly studied ginsenosides in the central nervous system, and their main metabolites on NMDA receptors using fura-2-based digital imaging and perforated whole-cell patch-clamp techniques. Among the nine ginsenosides tested, 20(S)-ginsenoside Rh2 (20(S)-Rh2) along with 20(S)-ginsenoside Rg3 (20(S)-Rg3) produced the highest inhibitory effect in cultured hippocampal neurons. Although 20(S)-Rg3 and 20(S)-Rh2 selectively targeted NMDA receptors with similar potency, they produced additive effects and seemed to modulate different NMDA receptor regulatory sites. As a competitive antagonist, 20(S)-Rh2 seems to inhibit the receptor via its interaction with polyamine-binding sites, and 20(S)-Rg3 does so using glycine-binding sites. Therefore, these results suggest that the treatment of 20(S)-Rh2, a newly identified active ingredient of ginseng, might be a novel preventive candidate in treating neurodegenerative disorders.

Animals↗

PubMed2006

Ginseng saponin metabolite suppresses phorbol ester-induced matrix metalloproteinase-9 expression through inhibition of activator protein-1 and mitogen-activated protein kinase signaling pathways in human astroglioma cells.

Aberrant expression of matrix metalloproteinase-9 (MMP-9) is implicated in the process of invasion and angiogenesis of malignant tumors as well as in inflammatory diseases of the CNS. Therefore, the development of compounds that can inhibit or suppress MMP-9 is required to treat brain tumors. We investigated the effects of a ginseng saponin metabolite, compound K (20-O-(beta-D-glucopyranosyl)-20(S)-protopanaxadiol), on MMP-9 expression in human astroglioma cells. Compound K significantly inhibited the secretion and protein expression of MMP-9 induced by PMA. The inhibitory effect of compound K on MMP-9 expression correlated with decreased MMP-9 mRNA levels and suppression of MMP-9 promoter activity. The compound K-mediated inhibition of MMP-9 gene expression appears to occur via AP-1 because its DNA-binding and transcriptional activities were suppressed by the agent. Furthermore, compound K significantly repressed the PMA-mediated activation of p38 MAPK, ERK and JNK, which are upstream modulators of AP-1. Finally, compound K inhibited the in vitro invasiveness of glioma cells. Therefore, inhibition of MMP-9 expression by compound K might have therapeutic potential for controlling the growth and invasiveness of brain tumors.

Astrocytoma↗

PubMed2006

Fast CT-PRESS-based spiral chemical shift imaging at 3 Tesla.

A new sequence is presented that combines constant-time point-resolved spectroscopy (CT-PRESS) with fast spiral chemical shift imaging. It allows the acquisition of multivoxel spectra without line splitting with a minimum total measurement time of less than 5 min for a field of view of 24 cm and a nominal 1.5x1.5-cm2 in-plane resolution. Measurements were performed with 17 CS encoding steps in t1 (Deltat1=12.8 ms) and an average echo time of 151 ms, which was determined by simulating the CT-PRESS experiment for the spin systems of glutamate (Glu) and myo-inositol (mI). Signals from N-acetyl-aspartate, total creatine, choline-containing compounds (Cho), Glu, and mI were detected in a healthy volunteer with no or only minor baseline distortions within 14 min on a 3 T MR scanner.

Algorithms↗

PubMed2006

Reducing gradient imperfections for spiral magnetic resonance spectroscopic imaging.

Spiral k-space magnetic resonance spectroscopic imaging (MRSI) requires high performance from gradient hardware systems. During the readout phase, oscillating gradients are continuously played out, which can cause undesired effects. These effects on the quality of SI data are non-intuitive because of their time-varying nature. In this work we describe the effects of undesirable gradient performance on SI. Measurements of the true readout trajectories were performed and the results were then used in the reconstruction process. The effects of these imperfections resulted in a spatially and spectrally varying amplitude and frequency modulation. The use of the measured trajectories in the reconstruction process yielded an up to 20% increase in signal amplitude recovery.

Computer Simulation↗

PubMed2006

The metabolism and excretion of 2-methylaminoethoxycarbonyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2'-carboxylic acid (DDB-S) in rats and human.

The metabolism and excretion of 2-methylaminoethoxycarbonyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2'-carboxylic acid (DDB-S) were investigated in both rats and humans using liquid chromatography/electrospray ion trap mass spectrometry (LC/ESI-MS/MS). In rats, DDB-S was rapidly eliminated from the body after a single 50 mg/kg intravenous injection, with urine being a major excretion route. DDB-S was metabolically stable; approximately 96% of the administered dose was recovered in the form of the parent compound. Nevertheless, 12 metabolites were detected in the urine and feces collected from DDB-S-treated rats. The structural characterizations of the metabolites were elucidated from the MS(n) spectral analysis. Because DDB-S has a pseudo-symmetrical methylenedioxy biphenyl structure, regioselective deuterium-substituted DDB-S (d(5)-DDB-S) was used to assign the metabolic modification. The major metabolic pathways of DDB-S were identified as demethylenation of the methylenedioxy moiety, O-demethylation of the methoxy moiety and glucuronidation. In addition, N-demethylation of the methylaminoethyl group was also detected as a minor reaction.

Animals↗

PubMed2006

Inhibitory effect of ginsenoside Rg5 and its metabolite ginsenoside Rh3 in an oxazolone-induced mouse chronic dermatitis model.

The effect of a main constituent ginsenoside Rg5 isolated from red ginseng and its metabolite ginsenoside Rh3 in a chronic dermatitis model was investigated. Ginsenosides Rg5 and Rh3 suppressed swelling of oxazolone-induced mouse ear contact dermatitis. These ginsenosides also reduced mRNA expressions of cyclooxygenase-2, interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. The inhibition of ginsenoside Rh3 was more potent than that of ginsenoside Rg5. These findings suggest that ginsenoside Rh3 metabolized from ginsenoside Rg5 may improve chronic dermatitis or psoriasis by the regulation of IL-1beta and TNF-alpha produced by macrophage cells and of IFN-gamma produced by Th cells.

Animals↗

PubMed2006

Effect of ginseng polysaccharide on the stability of lactic acid bacteria during freeze-drying process and storage.

Lactic acid bacteria (LAB) quickly attenuate or are killed during the freeze-drying process and storage. The effect of some natural polysaccharides, which are known as potent antitumor and immunomodulating substances, on the viability of the LAB, Lactobacillus acidophilus and Bifidobacterium breve, on freeze-drying and storage were investigated. Among the polysaccharides tested, red ginseng polysaccharide (RGP) and chitosan significantly inhibited the cell death of the LAB during freeze-drying, and fucoidan and RGP most potently protected the cell death of the LAB during storage. The stabilities of the LAB on the addition of RGP and fucoidan were comparable to that of skimmed milk. However, white ginseng polysaccharide (WGP) did not promote storage stability. When 5% skimmed milk/5% RGP treated LAB were freeze-dried and stored, their viabilities were found to be significantly higher those treated with 5% or 10% RGP. The stabilizing effect of 5% RGP/5% skimmed milk during LAB freeze-drying and storage stability was comparable to that of treatment with 10% skimmed milk. Based on these findings, we believe that RGP beneficially improves the stability of LAB during the freeze-dry process and storage.

Animals↗

PubMed2006

Lactic acid bacteria increase antiallergic effect of Artemisia princeps pampanini SS-1.

Artemisia princeps Pampanini, which is called Ssajuarissuk in Korean (SS-1), was fermented with lactic acid bacteria (LAB) and their passive cutaneous anaphylaxis reaction-inhibitory activity was investigated. Of these fermented agents, SS-1 extract fermented with Bifidobacterium infantis K-525 (F-SS-1) most effectively inhibited the release of P-hexosamindase from RBL-2H3 cells induced IgE. In IgE-induced RBL-2H3 cells, F-SS-1 inhibited proinflammatory cytokines IL-6 and TNF-alpha mRNA expression. Oral administration of SS-1 and F-SS-1 to mice inhibited passive cutaneous anaphylaxis (PCA) reaction induced by IgE and scratching behaviors induced by compound 48/80. The inhibitory activity of F-SS-1 against scratching behaviors was more effective than that of SS-1. These findings suggest that the fermentation of SS-1 with LAB can increase its antiallergic activity.

Animals↗