Biomedical subjects

Ki Young Lee

Publications and source records attributed to Ki Young Lee.

9 recordsLinked to original sources

PubMed2006

The expression of estrogen receptors in hepatocellular carcinoma in Korean patients.

Expression of estrogen receptors (ER)-alpha and -beta, as well as androgen receptor (AR), in hepatocellular carcinoma (HCC) is thought to be correlated with prognosis, survival, and male prevalence of HCC. These hypotheses are based on investigations of European patients; however the expression patterns of these receptors in Asian patients are largely unknown. In this study, we collected liver carcinoma and peritumor tissues from 32 patients (9 females and 23 males) in South Korea. The expression of ERs and ARs was studied using RT-PCR. Wild-type ER-alpha and AR were expressed in all of the samples investigated, and their expression was independent of the causal virus or patient sex. Expression of the ER-alpha variant was independent of sex (100% female vs. 91.3% male) and HCV and HBV status (91.3% vs. 100%). Wild-type ER-beta was expressed more often in HCV patients than in HBV patients (95.7% vs. 44.4%; p < 0.05). In conclusion, the stronger ER-alpha variant expression in HCC tissues implies that this variant has an important role in HCC development. However, at least in Korean patients, expression of the ER-alpha variant (vER-alpha) is not related to male HCC prevalence. In addition, the predominant expression of ER-beta in HCV patients suggests that it plays an important role in HCV-induced liver disease.

Aged↗

PubMed2006

Design and biological evaluation of novel tubulin inhibitors as antimitotic agents using a pharmacophore binding model with tubulin.

Although the structure has been elucidated for the binding of colchicine and podophyllotoxin as potent destabilizer for microtubule formation, very little is known about MDL-27048, a competitive inhibitor for colchicine and podophyllotoxin. The structural basis for the interaction of antimitotic agents with tubulin was investigated by molecular modeling, and we propose binding models for MDL-27048 against tubulin. The proposed model was not only consistent with previous competition experiment data between colchicine and MDL-27048, but further suggested an additional binding cavity on tubulin. Based on this finding from the proposed MDL-tubulin complex, we performed molecular design studies to identify new antimitotic agents. These new chalcone derivatives exerted growth inhibitory effects on all four human hepatoma and one renal epithelial cell lines tested and induced strong cell cycle arrest at G2/M phase. Furthermore, these compounds exhibited a strong inhibitory effect on tubulin polymerization in vitro. Therefore, we suggest that the validated MDL-27048 model would serve as a potent platform for designing new molecular entities for anticancer agents targeted to microtubules.

Cell Line↗

PubMed2006

Antifungal activity of synthetic peptide derived from halocidin, antimicrobial peptide from the tunicate, Halocynthia aurantium.

Halocidin is an antimicrobial peptide isolated from the hemocytes of the tunicate. Among the several known synthetic halocidin analogues, di-K19Hc has been previously confirmed to have the most profound antibacterial activity against antibiotic-resistant bacteria. This peptide has been considered to be an effective candidate for the development of a new type of antibiotic. In this study, we have assessed the antifungal activity of di-K19Hc, against a panel of fungi including several strains of Aspergillus and Candida. As a result, we determined that the MICs of di-K19Hc against six Candida albicans and two Aspergillus species were below 4 and 16 microg/ml, respectively, thereby indicating that di-K19Hc may be appropriate for the treatment of several fungal diseases. We also conducted an investigation into di-K19Hc's mode of action against Candida albicans. Our colony count assay showed that di-K19Hc killed C. albicans within 30s. Di-K19Hc bound to the surface of C. albicans via a specific interaction with beta-1,3-glucan, which is one of fungal cell wall components. Di-K19Hc also induced the formation of ion channels within the membrane of C. albicans, and eventually observed cell death, which was confirmed via measurements of the K+ released from C. albicans cells which had been treated with di-K19Hc, as well as by monitoring of the uptake of propidium iodide into the C. albicans cells. This membrane-attacking quality of di-K19Hc was also visualized via confocal laser and scanning electron microscopy.

Amino Acid Sequence↗

PubMed2005

Polyethylene glycol (PEG) modified 99mTc-HMPAO-liposome for improving blood circulation and biodistribution: the effect of the extent of PEGylation.

Modification of liposomes using polyethylene glycol (PEG) results in steric hindrance to the phagocyte system and prolongation of blood circulation time. However, PEGylation can reduce radiolabeling efficiency (RE) when using the glutathione method for radiolabeling the liposomes. Therefore, we investigated the effect of the extent of PEGylation (PEG extent (PEGExt): 0, 5, 9.6, and 13.7 mol%) on the in vivo biodistribution of liposomes in Wistar rats, and RE with technetium-(99m) ((99m)Tc). PEGylated liposomes were prepared with egg phosphatidylcholine (egg PC, 1.85 mol%), cholesterol (1.0 mol%), and distearoylphosphatidylethanolamine-N-[polyethylene glycol] (DSPE-PEG; 0, 5, 9.6, and 13.7 mol%, respectively). The size distribution of the PEGylated liposomes was analyzed by a dynamic light scattering. The (99m)Tc-hexamethylpropylene-amine oxime ((99m)Tc-HMPAO) complexes were used for radiolabeling of preformed liposomes. The labeling efficiency and stability was analyzed with Sephadex G-15 column, and the biodistribution studies of (99m)Tc-liposomes after intravenous (i.v.) injection were also investigated with Wistar rats. The sizes of PEGylated liposomes decreased by increasing the PEGExt to 9.6 mol%, whereas sizes increased at 13.7 mol%. RE of (99m)Tc were greater than 90% for all PEGExt tested, and radiolabeling stability in human plasma was enhanced as a function of PEGExt. Liposomes without PEG were cleared rapidly from the blood and accumulated preferentially in the liver and the spleen. When PEGExt was increased, the accumulation in the organs decreased. This accumulation of PEG was maximized at 9.6 mol%. Accumulation of the liposomes in the spleen was increased again when PEGExt increased to 13.7 mol%. The splenic uptake of liposomes seemed to be dependent not only on PEGExt but also on the size of the liposomes. In conclusion, the PEG chains on the surface of liposome have no influence on the labeling efficiency, and the prolongation of circulation time was maximized at the 9.6 mol% of PEGylation.

Animals↗

PubMed2005

Microbial conversion of major ginsenoside rb(1) to pharmaceutically active minor ginsenoside rd.

More than seventy strains of aerobic bacteria showing beta-glucosidase activity were isolated from a ginseng field, using a newly designed Esculin-R2A agar, and identified by their 16S rRNA gene sequences. Of these microorganisms, twelve strains could convert the major ginsenoside, Rb(1), to the pharmaceutically active minor ginsenoside Rd. Three strains, Burkholderia pyrrocinia GP16, Bacillus megaterium GP27 and Sphingomonas echinoides GP50, were phylogenetically studied, and observed to be most potent at converting ginsenoside Rb(1) almost completely within 48 h, as shown by TLC and HPLC analyses.

Agar↗

PubMed2004

Monoolein cubic phases containing hydrogen peroxide.

Monoolein (MO) cubic phases were prepared by hydrating MO using distilled water or 12wt.% H(2)O(2) solution so that the content of aqueous phase in the cubic phase is 30wt.%. The thermal transition of the isotropic cubic phase to reversed hexagonal phase was observed on a polarizing photomicroscope and the transition temperature was found to be around 65 degrees C on a differential scanning calorimeter (DSC). Small-angle X-ray scattering (SAXS) patterns indicated the cubic phases had diamond surfaces. The cubic phase released H(2)O(2) into an aqueous phase in a saturation manner so that approx. 50% of total loaded H(2)O(2) release in the first 10 h and thereafter relatively slow was observed over 40 h. The cubic phase was stable at 45 degrees C for 56 days before it broke down into an oily phase and an aqueous phase in 70 days. According to (1)H NMR spectrum, glycerol moiety and -CH(2)=CH(2)- of the oily phase were detected less in number than those of intact MO. Therefore, the hydrolysis and the oxidation of MO would be responsible for the breakdown of the cubic phase. The tensile adhesive forces of the cubic phases were higher than a skin-adhesive patch prepared using polyacrylate. The cubic phase containing H(2)O(2) could be used as a topical disinfected gel for a wounded skin.

Calorimetry, Differential Scanning↗

PubMed2004

Purification and cDNA cloning of a cecropin-like peptide from the great wax moth, Galleria mellonella.

A cecropin-like antimicrobial peptide, Gm cecropin, was purified from hemolymph of larvae of the wax moth, Galleria mellonella, immunized against E. coli, and its antibacterial activity was examined in a radial diffusion assay. The molecular mass of Gm cecropin was 4,160.69 Da by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry analysis. The full-length cDNA of the Gm cecropin precursor was cloned by a combination of RT-PCR, based on the N-terminal sequence obtained by Edman degradation, and 5'-RACE-PCR. Analysis of the cDNA showed that cecropin is synthesized as a prepropeptide, with a putative 22-residue signal peptide, a 4-residue propeptide and a 39-residue mature peptide with a calculated mass of 4,344.18 Da the difference between the calculated and measured masses suggests that Gm cecropin is a 37-residue peptide generated by removal of the C-terminal residue and amidation.

Amino Acid Sequence↗

PubMed2004

Kaistella koreensis gen. nov., sp. nov., a novel member of the Chryseobacterium-Bergeyella-Riemerella branch.

Gram-negative, non-spore-forming, rod-shaped, yellow-pigmented bacteria isolated from a freshwater stream in Korea were investigated to determine their taxonomic position. Complete 16S rRNA gene sequence analysis indicated that the organisms should be placed in the Chryseobacterium-Bergeyella-Riemerella branch in the family Flavobacteriaceae. Phylogenetically, the strains were most closely related to Chryseobacterium balustinum ATCC 33487(T) and Chryseobacterium scophthalmum LMG 13028(T) (94.3 and 94.1 % 16S rRNA gene sequence similarity, respectively) and they clustered on a separate well-supported branch. The strains contained menaquinone MK-6 as the predominant respiratory quinone and showed higher G+C contents (41.7 mol%) than other species in the Chryseobacterium-Bergeyella-Riemerella branch and i-C(15 : 0) as a major fatty acid (47-52 %). The phylogenetic distances from any species with validly published names and their phenotypic properties confirmed that the strains constitute a separate species in a new genus, for which the name Kaistella koreensis gen. nov., sp. nov. is proposed (type strain Chj707(T)=KCTC 12107(T)=IAM 15050(T)).

Bacterial Typing Techniques↗

PubMed2004

Effect of ketoconazole on the pharmacokinetics of rosiglitazone in healthy subjects.

AIMS: Fungal infection is a significant comorbidity in patients with diabetes mellitus, and ketoconazole, an antifungal agent, causes a number of drug interactions with coadministered drugs. Rosiglitazone is a novel thiazolidinedione antidiabetic drug, mainly metabolized by CYP2C8 and to a lesser extent CYP2C9. We investigated the possible effect of ketoconazole on the pharmacokinetics of rosiglitazone in humans. METHODS: Ten healthy Korean male volunteers were treated twice daily for 5 days with 200 mg ketoconazole or with placebo, using a randomized, open-label, two-way crossover study. On day 5, a single dose of 8 mg rosiglitazone was administered orally, and plasma rosiglitazone concentrations were measured. RESULTS: Ketoconazole increased the mean area under the plasma concentration-time curve for rosiglitazone by 47%[P = 0.0003; 95% confidence interval (CI) 23, 70] and the mean elimination half-life from 3.55 to 5.50 h (P = 0.0003; 95% CI in difference 1.1, 2.4). The peak plasma concentration of rosiglitazone was increased by ketoconazole treatment by 17% (P = 0.03; 95% CI 5, 29). The apparent oral clearance of rosiglitazone decreased by 28% after ketoconazole treatment (P = 0.0005; 95% CI 18, 38). CONCLUSIONS: This study revealed that ketoconazole affected the disposition of rosiglitazone in humans, probably by the inhibition of CYP2C8 and CYP2C9, leading to increasing rosiglitazone concentrations that could increase the efficacy of rosiglitazone or its adverse events.

Adult↗