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Y M Choi

Publications and source records attributed to Y M Choi.

At least 19 recordsLinked to original sources
PubMed2006

Increased telomerase activity and human telomerase reverse transcriptase mRNA expression in the endometrium of patients with endometriosis.

BACKGROUND: Endometriosis is considered a frequent, benign disease with the ability to undergo neoplastic processes. The aim of this study was to evaluate the limitless replication potential of the endometrium in patients with endometriosis by examining human telomerase reverse transcriptase (hTERT) mRNA expression and telomerase activity. METHODS: Endometrium samples from 30 endometriosis patients and 30 patients without endometriosis were obtained via endometrial biopsy. The expression of hTERT mRNA was determined by real-time RT-PCR assay, and telomerase activity was measured by telomerase repeat amplification protocol (TRAP) assay. RESULTS: The mean normalized hTERT (N hTERT) mRNA level was significantly higher in the endometriosis than in the control group (P = 0.013). The mean hTERT mRNA levels during the proliferative phase and during the secretory phase were higher in the endometriosis group than in the control group, although the difference was only significant for the secretory phase (P = 0.036). We found a prominent difference in endometrial telomerase activity between moderate-to-severe endometriosis and the control group (P = 0.048). The levels of hTERT mRNA and telomerase activity increased as the disease became more severe (P = 0.038, P = 0.016). CONCLUSIONS: This study showed the overexpression of hTERT mRNA and telomerase activity in the endometrium of endometriosis patients. These finding suggest that replication potential of endometrial cells may have an important role in the pathogenesis of endometriosis.

Adult↗
PubMed2006

Characterization of O2-CeO2 interactions using in situ Raman spectroscopy and first-principle calculations.

Interactions between O(2) and CeO(2) are examined experimentally using in situ Raman spectroscopy and theoretically using density-functional slab-model calculations. Two distinct oxygen bands appear at 825 and 1131 cm(-1), corresponding to peroxo- and superoxo-like species, respectively, when partially reduced CeO(2) is exposed to 10 % O(2). Periodic density-functional theory (DFT) calculations aid the interpretation of spectroscopic observations and provide energetic and geometric information for the dioxygen species adsorbed on CeO(2). The O(2) adsorption energies on unreduced CeO(2) surfaces are endothermic (0.91<DeltaE(ads)<0.98 eV), while those on reduced surfaces are exothermic (-4. 0<DeltaE(ads)<-0.9 eV), depending on other relevant surface processes such as chemisorption and diffusion into the bulk. Partial reduction of surface Ce(4+) to Ce(3+) (together with formation of oxygen vacancies) alters geometrical parameters and, accordingly, leads to a shift in the vibrational frequencies of adsorbed oxygen species compared to those on unreduced CeO(2). Moreover, the location of oxygen vacancies affects the formation and subsequent dissociation of oxygen species on the surfaces. DFT predictions of the energetics support the experimental observation that the reduced surfaces are energetically more favorable than the unreduced surfaces for oxygen adsorption and reduction.

Journal Article↗
PubMed2006

Immunoglobulin GM and KM genotypes in Korean patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune complex deposition. We genotyped immunoglobulin allotypes of G1M (f,z), G2M (n+,n-), G3M (b,g) and KM (1,3) in 142 Korean patients with SLE and 200 healthy controls to investigate the role of the allotypes in SLE. The allele frequency of G1M (z) was significantly higher in patients with SLE as compared to the healthy controls (94.6% vs. 84.3%, corrected P = 0.0004, OR 3.30, 95% CI 1.71-6.88). The frequency of G2M (n-) allele was also higher in patients with SLE (95.3% vs. 88.3%, corrected P = 0.008, OR = 2.71, 95% CI 1.38-5.72). Distribution of the tested allele frequencies for G3M and KM were not different between the patients and controls. In the respect of antibody production, there was increased genotype frequency of G1M (z/z) in anti-Sm(-) SLE (P = 0.023 vs. control, P = 0.042 vs. anti-Sm (+) SLE). In conclusion, particular genotypes at G1M (f,z) and G2M (n+,n-) loci are significantly associated with SLE. These immunoglobulin genes may contribute to the etiology of SLE and production of autoantibodies.

Adult↗
PubMed2006

Hypolipidemic effect of lactobacillus ferment as a functional food supplement.

The Lactobacillus ferment used in this study was composed of Lactobacillus fermented wheat, barley and kefir grains. Fermentation increased the CFU of lactic acid bacteria with a reduction in pH value and in the contents of dietary fi ber and glucan. Male SD rats were fed a high fat diet with or without 10% Lactobacillus ferment for 4 weeks. In the Lactic-F group (group fed high-fat diet with Lactobacillus ferment) there was a significantly reduced increase of body weight compared with the HF-control (group fed high-fat diet without Lactobacillus ferment). The food efficiency ratio (FER) tended to be decreased in the Lactic-F group, but there was no significant difference between the Lactic-F and HF-control groups. The perirenal and the epididymal fat weights in the normal dietary group (control) and in the Lactic-F group were significantly lower than those of the HF-control. The serum HDL-cholesterol and the total cholesterol in the Lactic-F group were similar to the control group, and were significantly different from those of the HF-control. These results indicated that the Lactobacillus ferment is a functional material having antiobesity effects, with use as a supplement in functional, health-favoring food.

Adipose Tissue↗
PubMed2006

FK506 increases pigmentation and migration of human melanocytes.

BACKGROUND: Topical tacrolimus (FK506) is a potential therapeutic option for vitiligo management. Despite its clinical efficacy, the underlying mechanism of how topical tacrolimus induces repigmentation in vitiligo has scarcely been investigated. OBJECTIVES: To investigate the direct effects of FK506 on pigmentation and migration of human melanocytes. METHODS: Cell proliferation was measured using a Coulter counter. The effects on pigmentation were investigated by measuring melanin contents, tyrosinase activity and tyrosinase expression. To determine the effects of FK506 on cell migration, we performed scratch assays and Boyden chamber assays. RESULTS: FK506 treatment increased melanin contents, although there was an inhibitory effect on growth of melanocytes. The increase of pigmentation was due to the result of the stimulatory action of FK506 on tyrosinase activity and its expression, which eventually led to melanin biosynthesis. Furthermore, cell migration was enhanced by FK506 treatment. CONCLUSIONS: These findings provide in vitro evidence demonstrating direct effects of FK506 on pigmentation and melanocyte migration and may provide a possible mechanism for the effect of tacrolimus in vitiligo.

Cell Movement↗
PubMed2004

Kinetics and mechanism of the C6H5 + CH3CHO reaction: experimental measurement and theoretical prediction of the reactivity toward four molecular sites.

The kinetics and mechanism of the reaction of C6H5 with CH3CHO have been investigated experimentally and theoretically. The total rate constant for the reaction has been measured by means of the cavity ring-down spectrometry (CRDS) in the temperature range 299-501 K at pressures covering 20-75 Torr. The overall bimolecular rate constant can be represented by the expression k = (2.8 +/- 0.2) x 10(11) exp[-(700 +/- 30)/T] cm3 mol-1 s-1, which is slightly faster than for the analogous C6H5 + CH2O reaction determined with the same method in the same temperature range. The reaction mechanism for the C6H5 + CH3CHO reaction was also explored with quantum-chemical calculations at various hybrid density functional theories (DFTs) and using ab initio high-level composite methods. The theories predict that the reaction may occur by two hydrogen-abstraction and two addition channels with the aldehydic hydrogen-abstraction reaction being dominant. The rate constant calculated by the transition state theory for the aldehydic hydrogen-abstraction reaction is in good agreement with the experimental result after a very small adjustment of the predicted reaction barrier (+0.3 kcal mol-1). Contributions from other product channels are negligible under our experimental conditions. For combustion applications, we have calculated the rate constants for key product channels in the temperature range of 298-2500 K under atmospheric-pressure conditions; they can be represented by the following expressions in units of cm 3mol-1 s-1: k1,cho = 8.8 x 10(3)T2.6 exp(-90/T), k2,ch3 = 6.0 x 10(1)T3.3 exp(-950/T), k3a(C6H5COCH3 + H) = 4.2 x 10(5)T0.6 exp(-410/T) and k3b(C6H5CHO + CH3) = 6.6 x 10(9)T-0.5 exp(-310/T).

Aldehydes↗
PubMed2004

Kinetics and mechanisms for the reactions of phenyl radical with ketene and its deuterated isotopomer: an experimental and theoretical study.

Kinetics and mechanism for the reaction of phenyl radical (C6H5) with ketene (H2C beta=C alpha=O) were studied by the cavity ring-down spectrometric (CRDS) technique and hybrid DFT and ab initio molecular orbital calculations. The C6H5 transition at 504.8 nm was used to detect the consumption of the phenyl radical in the reaction. The absolute overall rate constants measured, including those for the reaction with CD2CO, can be expressed by the Arrhenius equation k = (5.9 +/- 1.8) x 10(11) exp[-(1160 +/- 100)/T] cm3 mol-1 s-1 over a temperature range of 301-474 K. The absence of a kinetic isotope effect suggests that direct hydrogen abstraction forming benzene and ketenyl radical is kinetically less favorable, in good agreement with the results of quantum chemical calculations at the G2MS//B3LYP6-31G(d) level of theory for all accessible product channels, including the above abstraction and additions to the C alpha, C beta, and O sites. For application to combustion, the rate constants were extrapolated over the temperature range of 298-2500 K under atmospheric pressure by using the predicted transition-state parameters and the adjusted entrance reaction barriers E alpha = E beta = 1.2 kcal mol-1; they can be represented by the following expression in units of cm3 mol-1 s-1: k alpha = 6.2 x 10(19)T-23 exp[-7590/T] and k beta = 3.2 x 10(4)T2.4 exp[-246/T].

Journal Article↗
PubMed2004

Pharmacological effects of fermented red pepper.

The pharmacological effects were investigated of fermented red pepper (HF-S), which consisted of 14.7% carbohydrate, 1.5% lipid, 4.9% protein, 0.3% ash, 78.2% moisture content, with 0.15% capsaicin and 0.06% dihydrocapsaicin. Oral administration of 0.25 mL HF-S for 3 weeks produced significant changes of the perirenal fat pad weight compared with the HF-control group, suggesting a suppressive effect on lipid accumulation and a significant decrease in the risk of arteriosclerosis. The HF-S (0.25 mL) group also showed a lower plasma TG, TC level and atherogenic index than that of the HF-control. In addition, the HF-S (0.25 mL) group showed a marked increase in the production of glutathione, which is the major endogenous antioxidant, and a decrease in the production of lipid peroxide as the product of chemical damage by oxygen free radicals. It is assumed that the effect of HF-S might relate to high glutathione production on the suppression of lipid peroxidation. HF-S stimulated not only the proliferation of macrophages (as high as the positive control, LPS at 1000 microg/mL) but also mitogenic activity (1.2-fold of LPS at 100 microg/mL).

Administration, Oral↗
PubMed2004

Yeast hydrolysate reduces body fat of dietary obese rats.

The purpose of this study was to assess the antiobesity effect of the yeast hydrolysate (DNF) on the body weight, body fat and plasma lipids levels of high-fat fed rats. The weight gain of the HF (high fat diet) (162.58 +/- 6.68 g) was significantly (p < 0.05) greater than that of DNF-1, DNF-2, (high fat diet with DNF of 0.5 and 1.0 g/kg body weight, respectively) and control groups (143.19 +/- 7.33 g, 139.20 +/- 8.36 g, 130.23 +/- 8.02 g, respectively). The wet weight of the epididymal fat and the perirenal fat pads of the DNF-1, DNF-2 and control groups were reduced significantly (p < 0.05). A significant (p < 0.05) increase of HDL-cholesterol level of the DNF-2 and control groups was observed. However, there was no significant difference between DNF-1 and DNF-2. It was also found that the triacylglycerol (TG) levels decreased significantly (p < 0.05) in the DNF-2 group from that of the HF, but there was no significant (p < 0.05) difference between DNF-1 and DNF-2.

Adipose Tissue↗
PubMed2004

Wound botulism.

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Botulism↗
PubMed2001

School urinalysis screening in Korea: prevalence of chronic renal disease.

Since 1998, mass urine screening tests have been performed on Korean school children. We have analyzed those patients who showed abnormal urinary findings in the school screening program. Between January 1998 and January 2000, 452 children with abnormal urinary findings visited the Pediatric Kidney Center, Kyung-Hee University Hospital. Sex, age, 24-h urine creatinine clearance, ultrasonography, Doppler scans and renal biopsies were reviewed retrospectively. Results of initial urinalysis are divided into three groups: solely hematuria group (228 cases, 50.4%), solely proteinuria group (98 cases, 21.7%), and combined hematuria and proteinuria group (79 cases, 17.5%). Among the biopsied cases, the proportions representing renal parenchymal diseases were as follows: IgA nephropathy 11.3%, mesangial proliferative glomerulonephritis 21.9%, others 3.8%. Among the three groups, the combined hematuria and proteinuria group had more frequent chronic renal disease (57.7%) than the other groups. Chronic renal disease was detected in 36.9% of all visiting subjects. In the school screening program a significant number of patients showed abnormal urinary findings, which were associated with chronic renal diseases especially in the combined hematuria and proteinuria group. In conclusion, mass urine screening tests should be mandatory to detect asymptomatic chronic renal disease in school children.

Biopsy↗
PubMed2001

Identification of six novel MYH9 mutations and genotype-phenotype relationships in autosomal dominant macrothrombocytopenia with leukocyte inclusions.

The autosomal dominant macrothrombocytopenia with leukocyte inclusions, May-Hegglin anomaly (MHA), Sebastian syndrome (SBS), and Fechtner syndrome (FTNS), are rare platelet disorders characterized by a triad of giant platelets, thrombocytopenia, and characteristic Döhle body-like leukocyte inclusions. The locus for these disorders was previously mapped on chromosome 22q12.3-q13.2 and the disease gene was recently identified as MYH9, the gene encoding the nonmuscle myosin heavy chain-A. To elucidate the spectrum of MYH9 mutations responsible for the disorders and to investigate genotypephenotype correlation, we examined MYH9 mutations in an additional 11 families and 3 sporadic patients with the disorders from Japan. Korea, and China. All 14 patients had heterozygous MYH9 mutations, including three known mutations and six novel mutations (three missense and three deletion mutations). Two cases had Alport manifestations including deafness, nephritis, and cataracts and had R1165C and E1841K mutations, respectively. However, taken together with three previous reports, including ours, the data do not show clear phenotype-genotype relationships. Thus, MHA, SBS, and FTNS appear to represent a class of allelic disorders with variable phenotypic diversity.

Asia↗
PubMed2001

Increased expression of endoglin in the eutopic endometrium of women with endometriosis.

OBJECTIVE: To compare the angiogenic activities of endothelial cells in the eutopic endometrium of women with and without endometriosis. DESIGN: Vessels with active angiogenesis were identified using the monoclonal antibody to endoglin. SETTING: University department of obstetrics and gynecology. PATIENT(S): Twenty women with histologically confirmed endometriosis after laparotomy or laparoscopy. Women with carcinoma in situ of uterine cervix, but no evidence of endometriosis (n = 20), served as control subjects. INTERVENTION(S): Formalin-fixed, paraffin-embedded archival tissues were sectioned and stained. MAIN OUTCOME MEASURE(S): Number of vessels stained with monoclonal antibody to endoglin. RESULT(S): For all menstrual phases, the mean number of vessels with endoglin expression was significantly greater in patients with endometriosis compared with control subjects. In each menstrual phase, a significant difference was observed only during the late secretory phase. Within the group with endometriosis, the mean numbers of vessels with endoglin expression in stages I and II were not different from the numbers in stages III and IV. CONCLUSION(S): This study shows the expression of endoglin in the eutopic endometrium of women with endometriosis is significantly increased and the increase is observed only in the late secretory phase. It is suggested from these findings that activation of angiogenesis in the eutopic endometrium might be a key factor in the pathogenesis of endometriosis.

Adult↗
PubMed2001

Purification and properties of extracellular phytase from Bacillus sp. KHU-10.

Bacillus species producing a thermostable phytase was isolated from soil, boiled rice, and mezu (Korean traditinal koji). The activity of phytase increased markedly at the late stationary phase. An extracellular phytase from Bacillus sp. KHU-10 was purified to homogeneity by acetone precipitation and DEAE-Sepharose and phenyl-Sepharose column chromatographies. Its molecular weight was estimated to be 46 kDa on gel filtration and 44 kDa on SDS-polyacrylamide gel elctrophoresis. Its optimum pH and temperature for phytase activity were pH 6.5-8.5 and 40 degrees C without 10 mM CaCl2 and pH 6.0-9.5 and 60 degrees C with 10 mM CaCl2. About 50% of its original activity remained after incubation at 80 degrees C or 10 min in the presence of 10 mM CaCl2. The enzyme activity was fairly stable from pH 6.5 to 10.0. The enzyme had an isoelectric point of 6.8. As for substrate specificity, it was very specific for sodium phytate and showed no activity on other phosphate esters. The Km value for sodium phytate was 50 microM. Its activity was inhibited by EDTA and metal ions such as Ba2+, Cd2+, Co2+, Cr3+, Cu2+, Hg2+, and Mn2+ ions.

6-Phytase↗
PubMed2001

The influences of extremely low frequency magnetic fields on clonidine-induced sleep in 2-day-old chicks.

1. It has been shown that magnetic fields (MFs) affect a variety of biological effects in animal brains. There have been few experiments on the effects of MFs on sleep. Therefore, we investigated whether extremely low frequency (ELF) MFs affect the sleep induced by clonidine, a central alpha(2)-adrenoceptor agonist. Clonidine produced dose-related increase of the sleeping time and dose-related decrease of the onset time in 2-day-old chicks. 2. Exposure of chicks to MFs (5, 10, 20 G; for 3, 6, 9, 12 h) significantly increased the clonidine-induced sleep time as a direct function of intensity and duration of MF application. Clonidine reduced noradrenaline or tyrosine in the brain, an effect which was not further changed in animals exposed to MF. 3. To determine whether the gamma amino butyric acid A (GABA(A))/benzodiazepine (BZD) receptor system is involved in the decrease in clonidine-induced sleep caused by activation of central alpha(2)-adrenergic systems, we examined exposure of chicks to the effects of the BZD receptor antagonist flumazenil (0.5 mg kg(-1), i.p.) and GABA(A) antagonist bicuculline (0.1 mg kg-1, i.p.) on clonidine-induced sleep. Bicuculline and flumazenil inhibited the increase of clonidine-induced sleep time by MFs. Clonidine or MFs did not change GABA levels in the brain. 4. These results suggest that MFs can increase clonidine-induced sleep via a change of GABA(A) and BZD receptor system irrespective of the concentration of GABA or noradrenaline in the brain of 2-day-old chicks.

Adrenergic alpha-2 Receptor Agonists↗