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Biomedical subjects

S Y Moon

Publications and source records attributed to S Y Moon.

At least 19 recordsLinked to original sources
PubMed2006

Evaluation of a MF membrane system composed of pre coagulation-sedimentation and chlorination for water reuse.

In this research, we investigated the variation of transmembrane pressure and permeate water quality in pre-coagulation and sedimentation with iron based coagulant, and chlorination of feed water for PVDF (Polyvinylidene fluoride) based MF membrane filtration. NaCIO was fed to the membrane module at a dosage of 0.5 mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were employed. In the case of river surface water, the transmembrane pressure increased abruptly in 500 hours operation. On the contrary, no significant increase in transmembrane pressure was observed for coagulated water and coagulated-settled water for 1200 hours operation. The turbidity of permeate was lower than the detection limit for all applied waters. The removal efficiency for humic substances in coagulated water and coagulated-settled water was approximately ten times higher than that in surface river water. And, the removal efficiency for TOC and DOC was approximately two times higher than that in surface river water. From the results of the operation, it can be observed that it is possible to maintain stable operation at 0.9 m(3)/m(2)-day filtration flux through a combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when the pre-coagulation-sedimentation process was combined with pre-chlorination. With respect to fouling reduction and operation efficiency increase in membrane filtration, the pre-coagulation/sedimentation process is a promising alternative.

Filtration↗
PubMed2004

Complete nonvisualization of basilar artery on MR angiography in patients with vertebrobasilar ischemic stroke: favorable outcome factors.

BACKGROUND: In vertebrobasilar ischemic stroke, magnetic resonance angiography (MRA) occasionally fails to visualize the basilar artery, but in these patients, little attention has been given to establishing correlations between the clinical and the radiological findings. Our aim was to identify clinical or radiological measures that could assist in predicting a favorable clinical outcome. METHODS: Risk factors, clinicoradiological features, and functional outcomes were assessed in 40 patients with vertebrobasilar ischemic stroke whose basilar arteries were absent on MRA. The presence of potential feeding arteries to the posterior circulation was recorded from a review of the MRA data. To permit quantitative analysis of the images, a potential feeding artery score (PFAS; range: 0-8) was established. One point was assigned when a signal was seen from an intracranial vertebral artery, a posterior inferior cerebellar artery, a superior cerebellar artery, or a posterior cerebral artery. On MRI, the location of the infarction was classified as involving the proximal, middle, and distal territories of the intracranial posterior circulation. The infarctions were also categorized as single- or multi-sector infarctions, and according to whether more than one penetrating or branch artery was involved. Clinical outcomes were classified as favorable (modified Rankin Scale = 0-2) or poor (modified Rankin Scale = 3-6). RESULTS: The clinical outcome was favorable in 30% (n = 12) of patients, and poor in 70% (n = 28). A transient ischemic attack preceded the stroke in 48% of patients, especially those with a favorable outcome (67%). Patients with a favorable outcome had a higher PFAS (p = 0.036) and an increased incidence of single-sector infarction (p = 0.049). CONCLUSIONS: Our study suggests that a higher PFAS, accompanied by a single-sector infarction, is a predictor of improved clinical outcome in patients with vertebrobasilar ischemic stroke in which the basilar artery was absent on MRA.

Adult↗
PubMed2002

Serial diffusion-weighted MR Imaging in delayed postanoxic encephalopathy. A case study.

We report a case of delayed postanoxic encephalopathy (DPE) studied with serial diffusion weighted imaging five times in a one-year period along with apparent diffusion coefficient (ADC) map as well as ADC values of periventricular white matter. Compared to the normal value, the ADC values of the white matter were initially low on the three (0.68 +/- 0.08 x 10(-3) mm(2)/s) and seven-week images (0.67 +/- 0.08 x 10(-3) mm(2)/s) but gradually recovered to the normal range on the four, six, and twelve-month images (0.78 +/- 0.05, 0.80 +/- 0.05 and 0.87 +/- 0.11 x 10(-3) mm(2)/s, respectively). Among the several pathogenetic mechanisms associated with DPE, these serial changes may be consistent with cytotoxic edema, from apoptosis, triggered by hypoxia.

Activities of Daily Living↗
PubMed2001

Na,K-ATPase activity is required for formation of tight junctions, desmosomes, and induction of polarity in epithelial cells.

Na,K-ATPase is a key enzyme that regulates a variety of transport functions in epithelial cells. In this study, we demonstrate a role for Na,K-ATPase in the formation of tight junctions, desmosomes, and epithelial polarity with the use of the calcium switch model in Madin-Darby canine kidney cells. Inhibition of Na,K-ATPase either by ouabain or potassium depletion prevented the formation of tight junctions and desmosomes and the cells remained nonpolarized. The formation of bundled stress fibers that appeared transiently in control cells was largely inhibited in ouabain-treated or potassium-depleted cells. Failure to form stress fibers correlated with a large reduction of RhoA GTPase activity in Na,K-ATPase-inhibited cells. In cells overexpressing wild-type RhoA GTPase, Na,K-ATPase inhibition did not affect the formation of stress fibers, tight junctions, or desmosomes, and epithelial polarity developed normally, suggesting that RhoA GTPase is an essential component downstream of Na,K-ATPase-mediated regulation of these junctions. The effects of Na,K-ATPase inhibition were mimicked by treatment with the sodium ionophore gramicidin and were correlated with the increased intracellular sodium levels. Furthermore, ouabain treatment under sodium-free condition did not affect the formation of junctions and epithelial polarity, suggesting that the intracellular Na(+) homeostasis plays a crucial role in generation of the polarized phenotype of epithelial cells. These results thus demonstrate that the Na,K-ATPase activity plays an important role in regulating both the structure and function of polarized epithelial cells.

Animals↗
PubMed2001

CsRn1, a novel active retrotransposon in a parasitic trematode, Clonorchis sinensis, discloses a new phylogenetic clade of Ty3/gypsy-like LTR retrotransposons.

We screened the genome of a trematode, Clonorchis sinensis, in order to identify novel retrotransposons and thereby provide additional information on retrotransposons for comprehensive phylogenetic study. Considering the vast potential of retrotransposons to generate genetically variable regions among individual genomes, randomly amplified polymorphic DNAs (RAPDs) detected by arbitrarily primed polymerase chain reactions were selected as candidates for retrotransposon-related sequences. From RAPD analysis, we isolated and characterized a novel retrotransposon in C. sinensis as the first member of uncorrupted long-terminal-repeat (LTR) retrotransposons in phylum Platyhelminthes. The retrotransposon, which was named Clonorchis sinensis Retrotransposon 1 (CsRn1), showed a genomewide distribution and had a copy number of more than 100 per haploid genome. CsRn1 encoded an uninterrupted open reading frame (ORF) of 1,304 amino acids, and the deduced ORF exhibited similarities to the pol proteins of Ty3/gypsy-like LTR retrotransposons. The mobile activity of master copies was predicted by sequence analysis and confirmed by the presence of mRNA transcripts. Phylogenetic analysis of Ty3/gypsy-like LTR retrotransposons detected a new clade comprising CsRn1, Kabuki of Bombyx mori, and an uncharacterized element of Drosophila melanogaster. With its high repetitiveness and preserved mobile activity, it is proposed that CsRn1 may play a significant role in the genomic evolution of C. sinensis.

Amino Acid Sequence↗
PubMed2000

Oligomerization of Rac1 gtpase mediated by the carboxyl-terminal polybasic domain.

The Rho family GTPase Rac1 mediates a variety of signal transduction processes leading to activation of NADPH oxidase, actin cytoskeleton reorganization, transcription activation, and stimulation of DNA synthesis. In this study, Rac1 was found to form a reversible monomer and oligomer in both the GDP- and GTP-bound states in vitro and in cells. Mutational analysis and peptide competition experiments showed that the unique C-terminal domain of Rac1 consisting of six consecutive basic residues (amino acids 183-188) is required for the homophilic interaction. Oligomerization of Rac1-GTP led to a self-stimulatory GTPase-activating protein (GAP) activity, resulting in a significantly enhanced intrinsic GTP hydrolysis rate of Rac1-GTP. Deletion or mutation of the polybasic residues drastically decreased its intrinsic GTPase activity and resulted in a loss of the self-stimulatory GAP activity. In the oligomeric state, Rac1 became insensitive to the RhoGAP stimulation, albeit maintaining the responsiveness to the guanine nucleotide exchange factor. The ability of the Rac1 C-terminal mutants to activate the effector p21(cdc42/rac)-activated kinase-1 correlated with their oligomerization states, suggesting that oligomer formation potentiates effector activation. Furthermore, the oligomer-to-monomer transition of Rac1-GDP could be driven effectively by interaction with the Rho guanine nucleotide dissociation inhibitor. Building on previous characterizations of Rac1 interaction with regulatory proteins and effectors, these results suggest that Rac1 may employ yet another means of regulation by cycling between the monomeric and oligomeric states to effectively generate a transient and augmented signal.

Amino Acid Sequence↗
PubMed2000

Genetic deletion of the Pten tumor suppressor gene promotes cell motility by activation of Rac1 and Cdc42 GTPases.

Pten (Phosphatase and tensin homolog deleted on chromosome 10) is a recently identified tumor suppressor gene which is deleted or mutated in a variety of primary human cancers and in three cancer predisposition syndromes [1]. Pten regulates apoptosis and cell cycle progression through its phosphatase activity on phosphatidylinositol (PI) 3,4,5-trisphosphate (PI(3,4,5)P(3)), a product of PI 3-kinase [2-5]. Pten has also been implicated in controlling cell migration [6], but the exact mechanism is not very clear. Using the isogenic Pten(+/+) and Pten(-/-) mouse fibroblast lines, here we show that Pten deficiency led to increased cell motility. Reintroducing the wild-type Pten, but not the catalytically inactive Pten C124S or lipid-phosphatase-deficient Pten G129E mutant, reduced the enhanced cell motility of Pten-deficient cells. Moreover, phosphorylation of the focal adhesion kinase p125(FAK) was not changed in Pten(-/-) cells. Instead, significant increases in the endogenous activities of Rac1 and Cdc42, two small GTPases involved in regulating the actin cytoskeleton [7], were observed in Pten(-/-) cells. Overexpression of dominant-negative mutant forms of Rac1 and Cdc42 reversed the cell migration phenotype of Pten(-/-) cells. Thus, our studies suggest that Pten negatively controls cell motility through its lipid phosphatase activity by down-regulating Rac1 and Cdc42.

Animals↗
PubMed2000

Association of the vitamin D receptor start codon polymorphism (FokI) with bone mineral density in postmenopausal Korean women.

We undertook this study in order to examine the association between bone mineral density (BMD) and a polymorphism at the first of two potential translation initiation codons in the vitamin D receptor (VDR) gene. This polymorphism was detected by restriction fragment length polymorphism analysis, using polymerase chain reaction (PCR) and the restriction endonuclease FokI. The f allele indicates the presence of the FokI site, and the F allele its absence. The FokI genotype was determined in 174 postmenopausal Korean women, aged 43-71 years. The distribution of FokI genotypes in Koreans was found not to differ significantly from those found in Caucasians and Japanese, although it does differ significantly from that found in the black American population. We observed a significant association between the FokI polymorphism and lumbar BMD; P = 0.048, analysis of covariance [ANCOVA], but no association with femoral neck BMD (P = 0.505, ANCOVA). Those with the ff genotype had a 13.3% lower BMD in the lumbar spine than the FF subjects. In addition, a significantly higher prevalence of the ff genotype was observed in osteoporotic compared with osteopenic or normal women (P = 0.036, chi2 test). These data suggest that the ff genotype of the VDR gene correlates with decreased BMD in the lumbar spine in postmenopausal Korean women.

Base Sequence↗
PubMed2000

Carrier detection and prenatal diagnosis of hemophilia A in a Korean population by PCR-based analysis of the BclI/intron 18 and St14 VNTR polymorphisms.

We have undertaken this study to identify the usefulness of polymerase chain reaction (PCR)-based analysis of DNA polymorphisms in the BclI/intron 18 and St14 variable number of tandem repeats (VNTR) loci for carrier detection and prenatal diagnosis of hemophilia A in the Korean population. We have analyzed these polymorphisms in members of 105 unrelated Korean families with severe hemophilia A. The observed heterozygosity rates for the BclI/intron 18 and St14 VNTR polymorphisms were 21.0% and 71.3%, respectively. The BclI/intron 18 polymorphism was less informative in Koreans when compared with Caucasians and Japanese. The allele frequencies for St14 VNTR in Koreans were different from those in Caucasians. Compared with Caucasians, there was a markedly higher occurrence of low molecular weight alleles in Koreans. The observed heterozygosity for the St14 VNTR polymorphism in combination with the BclI/intron 18 polymorphism was 81.9%. These two polymorphisms were applied to determine the carrier status of 107 women from 65 unrelated families, and to assess fetal status in 37 pregnancies. So far, we have experienced one case of misdiagnosis of carriership. Our study demonstrated that the PCR-based analysis of the BclI/intron 18 and St14 VNTR polymorphisms was useful in the carrier detection and prenatal diagnosis of hemophilia A in the Korean population.

DNA↗
PubMed2000

Insulin-like growth factors (IGFs), IGF-binding proteins (IGFBPs), and IGFBP-3 protease activity in the peritoneal fluid of patients with and without endometriosis.

OBJECTIVE: To compare levels of insulin-like growth factor (IGF) components in the peritoneal fluid of patients with and without endometriosis. DESIGN: Patients with endometriosis were compared with control patients. SETTING: Seoul National University Hospital, Korea. PATIENT(S): Forty-three patients with endometriosis and 20 patients without endometriosis. INTERVENTION(S): Peritoneal fluid specimens were collected. MAIN OUTCOME MEASURE(S): Insulin-like growth factors, IGF binding protein (IGFBP) profiles and IGFBP-3 protease activity. RESULT(S): The IGF-I levels in peritoneal fluid were significantly higher in patients with endometriosis than in control patients, while the IGFBP-3 levels and the relative proportion of IGFBP-2 in peritoneal fluid were significantly lower in patients with endometriosis than in control patients. However, IGF-II levels, IGFBP-4 profiles, and IGFBP-3 protease activity did not differ significantly between the two groups. No correlation between these IGF components in peritoneal fluid and the stage of endometriosis was noted. CONCLUSION(S): The profiles of IGF components in peritoneal fluid of patients with pelvic endometriosis may play an important role in the growth of ectopic endometrium and endometriosis-induced infertility.

Adult↗
PubMed2000

Inhibition of RhoA by p120 catenin.

RhoA organizes actin stress fibres and is necessary for cell transformation by oncogenes such as src and ras. Moreover, RhoA is implicated in cadherin clustering during the formation of adherens junctions. The catenin p120 has also been implicated in cadherin clustering through an unknown mechanism. Here we show that p120 selectively inhibits RhoA activity in vitro and in vivo. RhoA inhibition and the interaction of p120 with cadherins are mutually exclusive, suggesting a mechanism for regulating the recruitment and exchange of RhoA at nascent cell-cell contacts. By affecting RhoA activation, p120 could modulate cadherin functions, including suppression of invasion, neurite extension and junction formation.

3T3 Cells↗
PubMed2000

Influence of female age on pregnancy outcome in in vitro fertilization and embryo transfer patients undergoing intracytoplasmic sperm injection.

PURPOSE: To determine the influence of female age on the outcomes of ICSI in IVF-ET patients. METHODS: One hundred and seventy-five couples underwent 352 cycles of ICSI. The quality of oocytes and embryos, fertilization rate, and pregnancy outcomes were retrospectively evaluated according to female age; < 30 years in Group A (49 cycles), 30-34 in Group B (177 cycles), 35-39 in Group C (97 cycles), and > or = 40 in Group D (29 cycles). RESULTS: The fertilization rates were not significantly different among the age groups. Significant negative linear correlations were observed between female age and the numbers of oocytes retrieved and embryos transferred, and cumulative embryo score. Clinical pregnancy rates were significantly decreased and spontaneous abortion rate increased with advancing age. CONCLUSIONS: Female age may be a prognostic indicator in ICSI program.

Adult↗
PubMed2000

Decreased expression of mac25 mRNA in uterine leiomyomata compared with adjacent myometrium.

PROBLEM: The pathogenesis of uterine leiomyomata is still unclear. Recently it has been suggested that mac25 plays a tumor-suppressive role in various tumors. The aims of this study were to evaluate a possible involvement of mac25 in the growth of leiomyoma and in the mechanism of a gonadotropin-releasing hormone agonist (GnRHa) inducing shrinkage of leiomyoma. METHODS OF STUDY: Mac25 mRNA transcript was measured by Northern blot in total RNA extracted from the paired specimens of leiomyoma and adjacent myometrium from untreated patients (n = 25) and from leiomyoma specimens from GnRHa-pretreated patients (n = 10). RESULTS: Mac25 mRNA expression was significantly lower in large leiomyoma (more than 150 cm3 in volume) than in adjacent myometrium and small leiomyoma (less than 120 cm3 in volume) from untreated patients. There was no difference in this expression between the proliferative and secretory phases of the menstrual cycle. Leiomyoma from GnRHa-pretreated patients had mac25 gene expression levels similar to myometrium and small leiomyoma from untreated patients. CONCLUSIONS: Mac25 may be involved in the growth of uterine leiomyoma and the action of GnRHa may, in part, be mediated by mac25.

Adult↗
PubMed1999

De novo direct duplication of 15q15-->q24 in a newborn boy with mild manifestations.

Duplication of distal 15q results in a recognizable clinical phenotype. We report here on a 25-day-old boy with a de novo interstitial duplication of chromosome region 15q15-q24. The manifestations in this patient are milder than those of previously described patients and include minor facial anomalies, velopharyngeal insufficiency, branchial cleft cyst, and hydronephrosis. Fluorescence in situ hybridization (FISH) using a chromosome 15 painting probe confirmed that the extra material is of chromosome 15 origin. Further analysis with the SNRPN probe demonstrated that the duplication is telomeric to the Prader-Willi/Angelman syndrome critical region. This case delineates a broader spectrum for patients with duplication 15q syndrome.

Abnormalities, Multiple↗