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Biomedical subjects

Y C Kim

Publications and source records attributed to Y C Kim.

At least 37 records · Page 2Linked to original sources
PubMed2003

Comparative bioavailability of silibinin in healthy male volunteers.

AIM: To study a comparative bioavailability of Liverman capsule to Legaion capsule and Silymarin tablet (which contain silibinin) in 24 healthy volunteers. VOLUNTEERS AND METHODS: Twenty-four healthy male Korean volunteers received each medicine at the silibinin dose of 120 mg in a 3 x 3 crossover study. There was a 1-week washout period among the doses. Plasma concentrations of silibinin were monitored by a high-performance liquid chromatography for over a period of 12 hours after the administration. AUCinf (the area under the plasma concentration-time curve from time zero to time infinity) was calculated by the trapezoidal rule extrapolation method. Cmax (maximum plasma drug concentration) and tmax (time to reach a Cmax) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed AUCinf, AUC(0-12h), and Cmax and untransformed tmax. RESULTS: After an oral administration of Liverman capsule, the pharmacokinetic parameters of silibinin, such as AUC(0-12h) (5.59, 4.24 and 13.9 microg/ml x h for Legalon capsule, Silymarin tablet and Liverman capsule, respectively) and AUCinf (6.00, 4.63 and 15.1 microg/ml x h) were significantly greater, Cmax (1.33, 1.13 and 6.04 microg/ml) was significantly higher and tmax (1.83, 2.10 and 0.875 h) was significantly faster than those after Legalon capsule and Silymarin tablet. CONCLUSION: These results indicate that the absorption and the extent of relative oral bioavailability of silibinin after Liverman capsule were significantly faster and greater, respectively, than those after Legalon capsule and Silymarin tablet.

Absorption↗
PubMed2003

Age-related change in serum concentrations of testosterone in middle-aged Korean men.

The objective of this study was to determine whether testosterone and sex hormone binding globulin (SHBG) levels are different between healthy men and men with chronic illness, and to evaluate the age-related changes of testosterone and SHBG in healthy men in Korea. enrollment took place between January 2000 and December 2001 at Pundang CHA General Hospital in Korea. All men who came for male climacteric and geriatric health screening examinations were eligible. Of the 762 men recruited, 136 men had at least one present or previous medical illness and 626 men were healthy. Higher serum concentrations of total testosterone (5.31 +/- 1.88 ng/ml vs. 4.96 +/- 1.43 ng/ml; p < 0.05), free androgen index (16.60 +/- 7.36 vs. 14.57 +/- 5.55; p < 0.01) and calculated bioavailable testosterone (8.88 +/- 3.52 nmol/l vs. 7.91 +/- 2.52 nmol/l; p < 0.01) were demonstrated in the healthy compared with the disease group. Total testosterone declined at a rate of 0.2% per year, SHBG increased by 1.74% per year, calculated bioavailable testosterone declined by 0.8% per year, and free androgen index declined by 1.15% per year in healthy subjects aged between 40 and 70. The above results seem to be consistent with previous Western studies, showing higher concentrations of testosterone in healthy men, that decline with increasing age.

Adult↗
PubMed2002

Room-temperature ferromagnetism in (Zn1-xMnx)GeP2 semiconductors.

We report on the discovery of a room-temperature ferromagnetic semiconductor in chalcopyrite (Zn1-xMnx)GeP2 with Tc = 312 K. We have also observed that, at temperatures below 47 K, samples for x = 0.056 and 0.2 show a transition to the antiferromagnetic (AFM) state, so that ferromagnetism is well defined to be present between 47 and 312 K. The observation that the AFM phase is most stable at low temperatures is consistent with the predictions of full-potential linearized augmented plane wave total energy calculations and has consequences for other chalcopyrite materials.

Journal Article↗
PubMed2002

Effects of luteolin on the inhibition of proliferation and induction of apoptosis in human myeloid leukaemia cells.

Luteolin, a flavonoid isolated from the fruit of Vitex rotundifolia, has been examined with regard to the inhibition of proliferation and induction of apoptosis in human myeloid leukaemia HL-60 cells. The concentration required for 50% inhibition of the growth after 96 h was 15 +/- 1.1 microM. The mode of cell death induced by luteolin was found to be apoptosis, as judged by the morphologic alteration of the cells and by the detection of DNA fragmentation using agarose gel electrophoresis. The degree of apoptosis was quantified by a sandwich enzyme immunoassay and flow cytometric analysis. These results suggest that luteolin may be used as potential chemopreventive and chemotherapeutic agents.

Antineoplastic Agents, Phytogenic↗
PubMed2002

Risk factors for epistaxis during nasotracheal intubation.

We performed a study to confirm which risk factors are significantly associated with epistaxis during nasotracheal intubation. One hundred patients who underwent nasotracheal intubation were included. Risk factors for epistaxis were analysed using the multiple logistic regression analysis with stepwise variable selection method. Epistaxis was most likely to occur if transit of the tube through the nasal passage was difficult (P=0.0001, odds ratio 625, 95% confidence interval 3.14-14.26). On the other hand, age and gender, obesity, smoking, tube size, repeated attempts of intubation, and intubation performed with the aid of Magillforceps were not significantly related with risk of epistaxis. The presence of nasal anatomical abnormalities also did not correlate significantly with epistaxis. Strategies to ensure smooth transit of the tube through the nasal passageways are essential to reduce the incidence of epistaxis.

Adult↗
PubMed2002

T-lymphocyte subsets in patients with AJCC stage III gastric cancer during postoperative adjuvant chemotherapy. American Joint Committee on Cancer.

BACKGROUND AND AIMS: Advanced neoplastic diseases alter the immune response in cancer patients. The aim of this study was to evaluate the changes of T-lymphocyte subsets during postoperative adjuvant chemotherapy, and the relationship between T-lymphocyte subsets and tumor recurrence in AJCC stage III gastric cancers. MATERIAL AND METHODS: Analysis of T-lymphocyte subsets was performed in 39 patients with stage III gastric adenocarcinoma who had undergone a curative gastric resection and postoperative chemotherapy. CirculatingT-lymphocyte subsets were measured on venous blood by using flow cytometry and monoclonal antibodies on preoperative day 1, and postoperative months 1, 3, and 6. RESULTS: The 5-year disease-free survival rates of patients with stage 3a and 3b gastric cancer were 57.1% and 33.3%, respectively (p = 0.06). Values of CD3+ and CD4+ T-cells, and CD4+/CD8+ ratios were consistently lower in the recurrence group throughout the observation period. CD4+ T-cell counts were significantly lower in the recurrence group on preoperative day 1, and postoperative months 1 and 6. However, most values of the T-lymphocyte subsets showed no statistically significant difference when comparing the stage 3a and 3b disease patient groups. CONCLUSIONS: The results of this study suggest that immunosuppression associated with CD3+ and CD4+ T-cell depression is a risk factor for postoperative recurrence in patients with stage III gastric cancer.

Adenocarcinoma↗
PubMed2001

Morphology and biology of parasite responsible for scuticociliatosis of cultured olive flounder Paralichthys olivaceus.

Based on the arrangement and shape of the buccal structure, scuticociliates isolated from cultured olive flounder Paralichthys olivaceus belonged to the family Uronematidae and showed many characteristics of Uronema marinum. There was variation in the morphometry of clinical isolates taken from different organs of infected flounder. However, the isolates did not show any significant difference in morphometry under cultured conditions. The ciliates were easily maintained in in vitro medium to which antibiotic agents had been added and which had been enriched with the raw brain tissue of a healthy olive flounder. The ciliates propagated in a wide range of both temperature (6 to 30 degrees C) and salinity (10 to 35 ppt).

Animals↗
PubMed2001

Apoptosis and bcl-2 expression as predictors of survival in radiation-treated non-small-cell lung cancer.

OBJECTIVES: We assessed the role of apoptosis and the expression of bcl-2, p53, and c-myc oncoproteins in pretreatment histologic specimens as a predictor of response to radiation therapy and survival in non-small-cell lung cancer (NSCLC) patients. METHODS: Pretreatment biopsy specimens of 68 patients with NSCLC (62 squamous cell carcinoma, 6 adenocarcinoma) were stained with hematoxylin and eosin. From 5 high-powered fields, the apoptotic index (AI) was calculated as the ratio of apoptotic tumor cells to the total number of tumor cells. Bcl-2, p53, and c-myc oncoprotein expression was detected by immunohistochemical staining. RESULTS: Twenty-nine cases showed partial or complete remission, whereas 39 showed no response. AI ranged from 0.2 to 12.0% (mean +/- SD; 4.3 +/- 2.6%, median 4.0%). There was no difference in AI between responders (4.0 +/- 2.3) and nonresponders (4.5 +/- 2.8, p > 0.05). However, in the responders, AI was correlated with the degree of change in tumor volume (r = 0.41, p < 0.05). In an analysis of 53 subjects who survived more than 1 month after the completion of radiation therapy, the patients with a higher AI (n = 27, MST = 22.8 m) survived longer than those with a lower AI (n = 26, MST = 9.2, log-rank, p = 0.03). Patients expressing bcl-2 had poorer survival (n = 22, MST = 6.0 m) than patients without bcl-2 (n = 31, 22.8 m, p < 0.003). According to multivariate analysis, three variables, bcl-2 expression, AI, and response to radiation, were independent prognostic factors for survival. CONCLUSION: A low level of spontaneous apoptosis and expression of apoptosis blocking bcl-2 protein in pretreatment histology predict a poor prognosis for radiation-treated NSCLC patients.

Adenocarcinoma↗
PubMed2001

Capsaicin inhibits the voltage-operated calcium channels intracellularly in the antral circular myocytes of guinea-pig stomach.

Studies of the effect of capsaicin (CAP) on the smooth muscle contractions have shown both contraction and relaxation in various preparations. The direct effect of CAP on gastric smooth muscle itself has not yet been reported, though CAP was reported to relax the isolated guinea-pig stomach by releasing nitric oxide from the CAP-sensitive sensory neurons. Here we showed an evidence that CAP evokes a prolonged relaxation of gastric antral circular smooth muscle (CAP-induced relaxation) by blocking the voltage-operated Ca2+ channels (VOCC) from inside of the cell. CAP suppressed dose-dependently the spontaneous contractions of guinea-pig gastric circular muscle strip under the condition without neural influence (IC50 = 5.8 microM). The inhibitory effects of CAP both on the high K+ contracture induced by 50 mM K+ Tyrode solution and on the slow waves recorded using a conventional intracellular microelectrode technique were similar to those of Ca2+ channel antagonists, indicating that Ca2+ influx through the VOCC is decreased by CAP. Ca2+ channel current (I(Ba)) decreased in a concentration-dependent manner on superfusing the physiological salt solution containing various concentrations of CAP. The steady-state activation and inactivation curves of I(Ba) were not affected by the treatment with CAP. The experiment using a synthetic water-soluble analog of CAP, DA-5018 x HCl, suggested that the acting site of CAP is present in the intracellular side. Spontaneous transient outward K+ currents (STOCs) recorded at a holding potential of 0 mV were also inhibited by CAP and verapamil, Ca channel blocker. Taken together, these results indicate that CAP-induced relaxation is associated with the direct inhibitory action on the VOCC from inside of the cell.

Animals↗
PubMed2001

[3H]MRS 1754, a selective antagonist radioligand for A(2B) adenosine receptors.

MRS 1754 [N-(4-cyanophenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)-phenoxy]acetamide] is a selective antagonist ligand of A(2B) adenosine receptors. This is the least well-defined adenosine receptor subtype, and A(2B) antagonists have potential as antiasthmatic drugs. For use as a radioligand, MRS 1754, a p-cyanoanilide xanthine derivative, was tritiated on the propyl groups in a two-step reaction using a p-carboxamido precursor, which was dehydrated to the cyano species using trifluoroacetic anhydride. [3H]MRS 1754 (150 Ci/mmol) bound to recombinant human A(2B) adenosine receptors in membranes of stably transfected HEK-293 cells. Specific binding was saturable, competitive, and followed a one-site model, with a K(D) value of 1.13 +/- 0.12 nM and a B(max) value of 10.9 +/- 0.6 pmol/mg protein. Specific binding utilizing 0.7 nM [3H]MRS 1754 was > 70% of total binding. The affinity calculated from association and dissociation binding constants was 1.22 nM (N = 4). Binding to membranes expressing rat and human A(1) and A(3) adenosine receptors was not significant, and binding in membranes of HEK-293 cells expressing human A(2A) receptors was of low affinity (K(D) > 50 nM). The effects of cations and chelators were explored. Specific binding was constant over a pH range of 4.5 to 6.5, with reduced binding at higher pH. The pharmacological profile in competition experiments with [3H]MRS 1754 was consistent with the structure-activity relationship for agonists and antagonists at A(2B) receptors. The K(i) values of XAC (xanthine amine congener) and CPX (8-cyclopentyl-1,3-dipropylxanthine) were 16 and 55 nM, respectively. NECA (5'-N-ethylcarboxamidoadenosine) competed for [3H]MRS 1754 binding with a K(i) of 570 nM, similar to its potency in functional assays. Thus, [3H]MRS 1754 is suitable as a selective, high-affinity radioligand for A(2B) receptors.

Acetamides↗
PubMed2001

Hemin-induced activation of the thioredoxin gene by Nrf2. A differential regulation of the antioxidant responsive element by a switch of its binding factors.

Thioredoxin plays an important role in various cellular processes through redox regulation. Here, we have demonstrated that thioredoxin expression is transcriptionally induced in K562 cells by hemin (ferriprotoporphyrin IX) through activation of a regulatory region positioned from -452 to -420 bp of the thioredoxin gene. Insertion of a mutation in the antioxidant responsive element (ARE)/AP-1 consensus binding sequence in this region abolished the response to hemin. With electrophoretic mobility shift and DNA affinity assays, we have shown that the NF-E2p45/small Maf complex constitutively binds to the ARE. The binding of the Nrf2/small Maf complex to ARE was induced by hemin, whereas the binding of Jun/Fos proteins to ARE was induced by phorbol 12-myristate 13-acetate, but not hemin. Hemin induced nuclear translocation of Nrf2 but did not affect nuclear expression of Jun/Fos proteins. Overexpression of Nrf2 augmented the response to hemin in a dose-dependent manner. In contrast, overexpression of the dominant negative mutant of Nrf2 suppressed hemin-induced activation through the ARE. We show here hemin-induced activation of the thioredoxin gene by Nrf2 through the ARE and propose a novel mechanism of the regulation of the ARE through a switch of its binding factors.

DNA-Binding Proteins↗
PubMed2001

Structure-activity relationships of pyridoxal phosphate derivatives as potent and selective antagonists of P2X1 receptors.

Novel analogues of the P2 receptor antagonist pyridoxal-5'-phosphate 6-azophenyl-2',5'-disulfonate (2) were synthesized and studied as antagonists in functional assays at recombinant rat P2X1, P2X2, and P2X3 receptors expressed in Xenopus oocytes (ion flux stimulation) and at turkey erythrocyte P2Y1 receptors (phospholipase C activation). Selected compounds were also evaluated as antagonists of ion flux and the opening of a large pore at the recombinant human P2X7 receptor. Modifications were made in the 4-aldehyde and 5'-phosphate groups of the pyridoxal moiety: i.e. a CH2OH group at the 4-position in pyridoxine was either condensed as a cyclic phosphate or phosphorylated separately to form a bisphosphate, which reduced potency at P2 receptors. 5-Methylphosphonate substitution, anticipated to increase stability to hydrolysis, preserved P2 receptor potency. At the 6-position, halo, carboxylate, sulfonate, and phosphonate variations made on the phenylazo ring modulated potency at P2 receptors. The p-carboxyphenylazo analogue, 4, of phosphate 2 displayed an IC50 value of 9 nM at recombinant P2X1 receptors and was 1300-, 16-, and > 10,000-fold selective for P2X1 versus P2X2, P2X3, and P2Y1 subtypes, respectively. The corresponding 5-methylphosphonate was equipotent at P2X1 receptors. The 5-methylphosphonate analogue containing a 6-[3,5-bis(methylphosphonate)]phenylazo moiety, 9, had IC50 values of 11 and 25 nM at recombinant P2X1 and P2X3 receptors, respectively. The analogue containing a phenylazo 4-phosphonate group, 11, was also very potent at both P2X1 and P2X3 receptors. However, the corresponding 2,5-disulfonate analogue, 10, was 28-fold selective for P2X1 versus P2X3 receptors. None of the analogues were more potent at P2X7 and P2Y1 receptors than 2, which acted in the micromolar range at these two subtypes.

Adenosine Triphosphate↗
PubMed2001

Activated ras oncogene collaborates with HBx gene of hepatitis B virus to transform cells by suppressing HBx-mediated apoptosis.

The hepatitis B virus HBx protein is a promiscuous transactivator implicated in the development of hepatocellular carcinoma. The ectopic expression of HBx fails to transform both primary and immortalized rodent cells, but rather induces apoptosis. Furthermore, most transgenic mice harboring HBx do not develop liver tumors. Thus, it remains unclear whether and how HBx contributes to oncogenesis. Here, we show that HBx collaborates with activated H-ras to transform immortalized rodent cells. Indeed, REF52 cells transfected by both HBx and activated H-ras were morphologically transformed and were able to grow in soft agar. Remarkably, nude mice injected with REF52 cells transfected by both HBx and activated H-ras developed tumors, whereas the mice injected with REF52 cells transfected by either gene alone did not. Thus, we concluded that HBx could contribute to neoplastic transformation of cells in collaboration with other oncogenes, such as H-ras, that renders cells to overcome the HBx-mediated apoptosis. Further, we found that HBx mediated apoptosis was suppressed by activated H-ras through activation of the phosphatidylinositol-3 kinase and Akt pathway. Data presented here firmly established the oncogenic potential of HBx during multistage carcinogenesis. Oncogene (2001) 20, 16 - 23.

3T3 Cells↗
PubMed2001

Rotundifuran, a labdane type diterpene from Vitex rotundifolia, induces apoptosis in human myeloid leukaemia cells.

The inhibitory effect of rotundifuran, a labdane type diterpene isolated from the fruit of Vitex rotundifolia, on the proliferation of human myeloid leukaemia HL-60 cells was examined. The concentration required for 50% inhibition of the growth after 96 h was 22.5 microM. The mode of cell death induced by rotundifuran was found to be apoptosis, which was judged by the morphological alteration of the cells and by the detection of DNA fragmentation using agarose gel electrophoresis. The degree of apoptosis was quantified by a sandwich enzyme immunoassay and flow cytometric analysis. These results suggest that rotundifuran may be used as a potential chemopreventive and chemotherapeutic agent.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Lignan and neolignan glycosides from Ulmus davidiana var. japonica.

Four lignan xylosides and two neolignan glycosides were isolated from the stem and root barks of Ulmus davidiana var. japonica. Their structures were identified as lyoniside, nudiposide, 5'-methoxyisolariciresinol-9'-O-beta-D-xylopyranoside, isolariciresinol-9'-O-1-D-xylopyranoside, rel-trans-dihydrodehydroconiferyl alcohol 4'-O-alpha-L-rhamnopyranoside and icariside E3 by comparison of their spectral data with those reported in the literatures, respectively.

Chromatography, Ion Exchange↗
PubMed2001

Coumarins isolated from Angelica gigas inhibit acetylcholinesterase: structure-activity relationships.

Acetylcholinesterase (AChE) inhibitory activity-guided fractionation of Angelica gigas led to isolation and identification of a new coumarin, peucedanone (12), and isolation of 11 known coumarins. Among them, decursinol (1) represented the highest inhibitory activity toward AChE in vitro. The correlation of the inhibitory activities of the coumarins toward AChE with their chemical structures was studied.

Cholinesterase Inhibitors↗
PubMed2001

Five novel neuroprotective triterpene esters of Ulmus davidiana var. japonica.

Investigation of the constituents of the stem and root barks of Ulmus davidiana var. japonica resulted in the isolation of five new triterpene esters named ulmicin A-E (1-5). Using several spectroscopic techniques, their structures were determined to be 3beta,11alpha,15alpha-trihydroxylup-20(29)-ene-11-(3'-methoxy-4'-hydroxybenzoyl ester) (1), 3beta,11alpha,15alpha-trihydroxylup-20(29)-ene-11-(4'-hydroxybenzoyl ester) (2), 3beta,11alpha,15alpha-trihydroxylup-20(29)-ene-11-(3'-methoxy-4'-hydroxybenzoyl)-15-(4'-hydroxybenzoyl ester) (3), 3beta,11alpha,15alpha-trihydroxylup-20(29)-ene-11,15-di(3'-methoxy-4'-hydroxybenzoyl ester) (4), and 3beta,11alpha,15alpha-trihydroxylup-20(29)-ene-11-(3'-methoxy-4'-hydroxybenzoyl)-15-(benzoyl ester) (5). All five compounds showed significant neuroprotective activities against glutamate-induced neurotoxicity in primary cultures of rat cortical cells.

Animals↗