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C H Kim

Publications and source records attributed to C H Kim.

At least 55 records · Page 3Linked to original sources
PubMed2001

Genomic structure of human GM3 synthase gene (hST3Gal V) and identification of mRNA isoforms in the 5'-untranslated region.

GM3 synthase, which transfers CMP-NeuAc with an alpha2,3-linkage to a galactose residue of lactosylceramide, plays a key role in the biosynthesis of all complex gangliosides. In this study, cDNA and genomic clones encoding human GM3 synthase (hST3Gal V) were isolated, and the structural organization of the gene was determined. The hST3Gal V cDNA was identical in the coding region with cDNA that has been cloned previously from the HL-60 cells but different in the 5'-untranslated region (UTR). The hST3Gal V gene consisted of nine exons, which span approximately 44 kb, with exons ranging in size from 112 to 1242 bp. The coding region was located in exons 4-9, and all exon-intron boundaries except the acceptor site of intron 1 followed the GT-AG rule. The expression of this gene was highly restricted in both human fetal and adult tissues. By comparison of the nucleotide sequences of the genomic DNA with cDNA sequences including 5'-RACE products, we identified four isoforms (types 1-4) of the hST3Gal V mRNA that differ only in the 5'-UTR. Structural analysis of these isoforms suggests that mRNA isoforms of hST3Gal V are produced by a combination of alternative splicing and alternative promoter utilization.

5' Untranslated Regions↗
PubMed2001

IFN-gamma induces cell death in human hepatoma cells through a TRAIL/death receptor-mediated apoptotic pathway.

We demonstrated the induction of cell death in a hepatoma cell line by IFN-gamma and its possible mechanism. Among the 2 hepatitis B virus (HBV)-associated hepatoma cell lines, SNU-354 and SNU-368, IFN-gamma induced cell death and increased caspase-3 activity in SNU-368 but not in SNU-354. IFN-gamma induced several changes in the mRNA expression level of apoptosis-regulating genes, e.g., increased expression of Fas, caspase-1 and TNF-related apoptosis-inducing ligand (TRAIL). In particular, IFN-gamma potently increased the mRNA expression of TRAIL in both cell lines. However, it did not change the mRNA expression level of death-mediating TRAIL receptors, e.g., DR4 and DR5, which were constitutively expressed in both cell lines. In contrast, the decoy receptor DcR1 was expressed in SNU-354 but not in SNU-368, and its expression level in SNU-354 was increased by IFN-gamma. Another decoy receptor, DcR2, was constitutively expressed in both cell lines; however, its expression level in SNU-368 was decreased by IFN-gamma. In addition, exogenous recombinant TRAIL reduced viability in SNU-368, but not in SNU-354, cells. From these findings, we speculated that TRAIL up-regulation and the subsequent TRAIL-mediated apoptosis serve as a mechanism of IFN-gamma-induced cell death in SNU-368. To confirm this hypothesis, we demonstrated that soluble DR4-Fc fusion protein, a TRAIL pathway inhibitor, inhibited IFN-gamma-induced cell death in SNU-368. Our results demonstrated that IFN-gamma acts as an inducer of cell death through TRAIL-mediated apoptosis.

Apoptosis↗
PubMed2001

Subspecialization of CXCR5+ T cells: B helper activity is focused in a germinal center-localized subset of CXCR5+ T cells.

The T helper (Th) cell pool is composed of specialized cells with heterogeneous effector functions. Apart from Th1 and 2 cells, CXCR5+ T cells have been suggested to be another type of effector T cell specialized for B cell help. We show here that CXCR5+ T cells are heterogeneous, and we identify subsets of CXCR5+ CD4 T cells that differ in function and microenvironmental localization in secondary lymphoid tissues. CD57+CXCR5 T cells, hereafter termed germinal center Th (GC-Th) cells, are localized only in GCs, lack CCR7, and are highly responsive to the follicular chemokine B lymphocyte chemoattractant but not to the T cell zone EBI1-ligand chemokine. Importantly, GC-Th cells are much more efficient than CD57-CXCR5+ T cells or CXCR5- T cells in inducing antibody production from B cells. Consistent with their function, GC-Th cells produce elevated levels of interleukin 10 upon stimulation which, with other cytokines and costimulatory molecules, may help confer their B cell helper activity. Our results demonstrate that CXCR5+ T cells are functionally heterogeneous and that the GC-Th cells, a small subset of CXCR5+ T cells, are the key helpers for B cell differentiation and antibody production in lymphoid tissues.

B-Lymphocytes↗
PubMed2001

A labile component of AMPA receptor-mediated synaptic transmission is dependent on microtubule motors, actin, and N-ethylmaleimide-sensitive factor.

Glutamate receptor channels are synthesized in the cell body, are inserted into intracellular vesicles, and move to dendrites where they become incorporated into synapses. Dendrites contain abundant microtubules that have been implicated in the vesicle-mediated transport of ion channels. We have examined how the inhibition of microtubule motors affects synaptic transmission. Monoclonal antibodies that inactivate the function of dynein or kinesin were introduced into hippocampal CA1 pyramidal cells through a patch pipette. Both antibodies substantially reduced the AMPA receptor-mediated responses within 1 hr but had no effect on the NMDA receptor-mediated response. Heat-inactivated antibody or control antibodies had a much smaller effect. A component of transmission appeared to be resistant even to the combination of these inhibitors, and we therefore explored whether other agents also produce only a partial inhibition of transmission. A similar resistant component was found by using an actin inhibitor (phalloidin) or an inhibitor of NSF (N-ethylmaleimide-sensitive fusion protein)/GluR2 interaction. We then examined whether these effects were independent or occluded each other. We found that a combination of phalloidin and NSF/GluR2 inhibitor reduced the response to approximately 30% of baseline level, an effect only slightly larger than that produced by each agent alone. The addition of microtubule motor inhibitors to this combination produced no further inhibition. We conclude that there are two components of AMPA receptor-mediated transmission; one is a labile pool sensitive to NSF/GluR2 inhibitors, actin inhibitors, and microtubule motor inhibitors. A second, nonlabile pool resembles NMDA receptor channels in being nearly insensitive to any of these agents on the hour time scale of our experiments.

Actins↗
PubMed2001

An E-box motif residing in the exon/intron 1 junction regulates both transcriptional activation and splicing of the human norepinephrine transporter gene.

The norepinephrine transporter (NET) is responsible for the rapid NaCl-dependent uptake of norepinephrine into presynaptic noradrenergic nerve endings. Recently, we have characterized the structural organization of the 5' upstream promoter region of the human NET (hNET) gene. A new intron of 476 base pairs was found in the middle of the 5'-untranslated leader sequence and was shown to robustly enhance the promoter activity. Here, we show that the first hNET intron enhances both the homologous hNET and the heterologous thymidine kinase promoter activities in an orientation- and position-dependent manner. The first hNET intron exhibited a similar promoter-enhancing effect in both SK-N-BE(2)C (NET-positive) and HeLa (NET-negative) cell lines, showing that its function is not cell-specific. Transient transfection assays of a series of deletional constructs show that the first hNET intron contains subdomains with either positive or negative regulatory functions. Furthermore, DNase I footprinting analysis demonstrated that the 5' side of the intron, encompassing the splice donor site, is prominently protected by nuclear proteins isolated from both SK-N-BE(2)C and HeLa cells. The protected nucleotide sequence contains a consensus E-box motif, known to regulate diverse eukaryotic genes, which overlaps with the splice donor site of the first intron. We demonstrate that two basic helix-loop-helix proteins, upstream stimulatory factors 1 and 2, are major proteins interacting at this site and that the E-box is at least in part responsible for the promoter-enhancing activity of the first intron. Furthermore, site-directed mutagenesis of the splice donor site of the first intron affects both correct splicing and transcriptional activity. Taken together, our results indicate that a cis-element residing at the first exon/intron junction, encompassing an E-box motif, has a unique dual role in basal transcriptional activation and splicing of hNET mRNA.

Base Sequence↗
PubMed2001

Structural and thermodynamic studies on mutant RNA motifs that impair the specificity between a viral replicase and its promoter.

The 3'-end region of the genomic RNA of brome mosaic virus forms a tRNA-like structure that is critical for its replication. Previous studies have shown that in this region, a stem-loop structure, called SLC, is necessary and sufficient for the binding of the RNA replicase, and for RNA replication. Recently, we determined the high-resolution NMR structure of SLC, which demonstrated that a 5'-AUA-3' triloop region is an important structural element for the enzymatic recognition. We proposed that the 5'-adenine of the triloop, which is rigidly fixed ("clamped") to the stem, is a key recognition element for the replicase. To elucidate the role of this "clamped base motif" for the enzymatic recognition, we have now investigated the solution conformations of several stem-loop molecules with mutant triloops, 5'-UUA-3', 5'-GUA-3', 5'-CUA-3' and 5'-UUU-3', that destroy the enzymatic recognition. For the GUA and UUA mutants, we have obtained high-resolution solution structures using 2D NMR. All four mutants have very similar thermodynamic stabilities, and all have the same secondary structures, a triloop with a five base-paired stem helix. In addition, they have quite similar sugar puckering patterns in the triloop region. The NMR structures of the GUA and UUA show that the 5' nucleotide of the triloop (G6 in GUA or U6 in UUA) lacks the strong interactions that hold its base in a fixed position. In particular, the U6 of UUA is found in two different conformations. Neither of these two mutants has the clamped base motif that was observed in the wild-type. While UUA also shows global change in the overall triloop conformation, GUA shows a very similar triloop conformation to the wild-type except for the lack of this motif. The absence of the clamped base motif is the only common structural difference between these two mutants and the wild-type. These results clearly indicate that the loss of function of the UUA and GUA mutants comes mainly from the destruction of a small key recognition motif rather than from global changes in their triloop conformations. Based on this study, we conclude that the key structural motif in the triloop recognized by the replicase is a solution-exposed, 5'-adenine base in the triloop that is clamped to the stem helix, which is called a clamped adenine motif.

Adenine↗
PubMed2001

Nonenteric Escherichia coli isolates from dogs: 674 cases (1990-1998).

OBJECTIVE: To determine nonenteric sites associated with Escherichia coli isolates in dogs and the antimicrobial susceptibilities of the isolates. DESIGN: Retrospective study. SAMPLE POPULATION: 17,000 canine specimens. PROCEDURE: Medical records of 17,000 canine specimens submitted for bacteriologic culture were examined and the number of isolations of E coli was determined. For these cases, records were further examined with respect to body system involvement, sex, concurrent infection with other species of bacteria, and antimicrobial susceptibility. RESULTS: 674 E coli isolates (424 from urine, 62 from the skin, 52 from the respiratory tract, 45 from the ear, 43 from the female reproductive tract, 25 from the male reproductive tract, and 23 from other organ systems) were identified. There was a significantly higher proportion of isolates from urine specimens from spayed females than from sexually intact females or males. Escherichia coli was isolated in pure culture from 65.9% of the specimens. Most E coli isolates were susceptible to norfloxacin (90%), enrofloxacin (87.5%), gentamicin (90.7%), and amikacin (85.9%). CONCLUSIONS AND CLINICAL RELEVANCE: Most nonenteric E coli infections in dogs involve the urinary tract. Amikacin, gentamicin, norfloxacin, and enrofloxacin have the highest efficacy against canine E coli isolates. For E coli isolates from dogs, in vitro susceptibility to commonly used antimicrobial agents has remained fairly stable during the past decade.

Amikacin↗
PubMed2001

A quantitative-trait analysis of human plasma-dopamine beta-hydroxylase activity: evidence for a major functional polymorphism at the DBH locus.

Dopamine-beta-hydroxylase (D beta H) catalyzes the conversion of dopamine to norepinephrine and is released from sympathetic neurons into the circulation. Plasma-D beta H activity varies widely between individuals, and a subgroup of the population has very low activity levels. Mounting evidence suggests that the DBH structural gene is itself the major quantitative-trait locus (QTL) for plasma-D beta H activity, and a single unidentified polymorphism may account for a majority of the variation in activity levels. Through use of both sequencing-based mutational analysis of extreme phenotypes and genotype/phenotype correlations in samples from African American, European American (EA), and Japanese populations, we have identified a novel polymorphism (--1021C-->T), in the 5' flanking region of the DBH gene, that accounts for 35%--52% of the variation in plasma-D beta H activity in these populations. In EAs, homozygosity at the T allele predicted the very low D beta H-activity trait, and activity values in heterozygotes formed an intermediate distribution, indicating codominant inheritance. Our findings demonstrate that --1021C-->T is a major genetic marker for plasma-D beta H activity and provide new tools for investigation of the role of both D beta H and the DBH gene in human disease.

Amino Acid Substitution↗
PubMed2001

C-C chemokine receptor 4 expression defines a major subset of circulating nonintestinal memory T cells of both Th1 and Th2 potential.

CCR4, a chemokine receptor for macrophage-derived chemokine (MDC) and thymus and activation-regulated chemokine (TARC), has been implicated as a preferential marker for Th2 lymphocytes. Following in vitro polarization protocols, most Th2 lymphocytes express CCR4 and respond to its ligands TARC and MDC, whereas Th1 lymphocytes express CXC chemokine receptor 3 and CCR5 (but not CCR4). We show in this study that CCR4 is a major receptor for MDC and TARC on T lymphocytes, as anti-CCR4 mAbs significantly inhibit the migration of these cells to MDC and TARC. CCR4 is also highly expressed in most single-positive CD4(+) thymocytes and on a major fraction of blood nonintestinal (alpha(4)beta(7)(-)) memory CD4 lymphocytes, including almost all skin memory CD4(+) cells expressing the cutaneous lymphocyte Ag (CLA), but weakly or not expressed in other subsets in thymus and blood. Interestingly, major fractions of circulating CCR4(+) memory CD4 lymphocytes coexpress the Th1-associated receptors CXC chemokine receptor 3 and CCR5, suggesting a potential problem in using these markers for Th1 vs Th2 lymphocyte cells. Moreover, although production of Th2 cytokines in blood T cells is associated with CCR4(+) CD4 lymphocytes, significant numbers of freshly isolated circulating CCR4(+) memory CD4 lymphocytes (including both CLA(+) and CLA(-) fractions) readily express the Th1 cytokine IFN-gamma after short-term stimulation. Our results are consistent with a role for CCR4 as a major trafficking receptor for systemic memory T cells, and indicate that the patterns and regulation of chemokine receptor expression in vivo are more complex than indicated by current in vitro models of Th1 vs Th2 cell generation.

Animals↗
PubMed2001

Two cases of primary malignant melanoma of the lacrimal sac.

BACKGROUND: Malignancy of the lacrimal sac is rare, and primary malignant melanoma in this region is extremely rare. METHODS: We report two cases of malignant melanoma of the lacrimal sac presented with epiphora and a palpable mass in the medial canthal area. We performed radical surgery and radiation therapy. RESULTS: The light microscopic, immunohistochemical, and electron microscopic studies confirmed the diagnosis. One of the patients, a 65-year-old-woman, has no evidence of recurrence or distant metastasis 3 years after surgery and radiotherapy, whereas another patient, a 56-year-old man, died of distant metastasis 6 months after surgery and radiotherapy. CONCLUSIONS: We present two cases of malignant melanoma of the lacrimal sac that masqueraded as chronic dacryocystitis. Head and neck surgeons should be aware of this disease entity when encountered with patients with epiphora and mass in the medial canthal area.

Aged↗
PubMed2001

Inhibitory effect on immunoglobulin E production in vivo and in vitro by Siegesbeckia glabrescens.

Elevated levels of immunoglobulin (Ig)E are associated with immediate-type allergic reactions. The effect of an aqueous extract of Siegesbeckia glabrescens (Compositae) whole plants (SGWP) on in vivo and in vitro IgE production was studied in mice. SGWP dose-dependently inhibited the active systemic anaphylaxis and serum IgE production induced by immunization with ovalbumin and Bordetella pertussis toxin absorbed to aluminium hydroxide gel. SGWP dose-dependently inhibited IL-4-dependent IgE production by lipopolysaccharide-stimulated murine whole spleen cells. In the case of U266 human IgE-bearing B cells, SGWP also showed an inhibitory effect on IgE production. These results suggest that SGWP has an anti-allergic activity by inhibiting IgE production from B cells.

Anaphylaxis↗
PubMed2001

Bombycis corpus extract prevents amyloid-beta-induced cytotoxicity and protects superoxide dismutase activity in cultured rat astrocytes.

Bombycis corpus(BC) or Bombyx Batryticatus, a batryticated silkworm and white-stiff silkworm, is a drug consisting of the dried larva of silkworm, Mobyz mori L., dead and stiffened due to the infection of Beauveria (Bals.) Vuill. In the present study, we have examined the protective effect of the water extracts against Amyloid- beta(A beta) 25-35 peptide-induced cytotoxicity by microscopic observation and LDH assay, and its action on antioxidative enzymes using cultured astrocyte cells. A beta 25-35-induced cell death was protected by the application of water extract of BC in a dose-dependent manner, and concentrations of 10(-6)to 10(-7)g ml(-1)showed a significant effect compared to exposure of A beta 25-35 alone. When antioxidative enzyme activities such as catalase, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione-S transferase (GST) were assayed after A beta 25-35 treatment, most enzyme activities were decreased in a similar fashion. BC treatment of A beta 25-35-treated astrocytes did not affect the enzyme activities of catalase, GSH-Px and GST. However, only SOD activity was enhanced by BC treatment and this may result from the potentiation of the antioxidative ability of BC. The protective effect of BC against cytotoxicity induced by Abeta 25-35 strongly indicates that BC could be a protective agent for free radical generating compounds, and that Abeta 25-35 is not only a potent lipid peroxide inducer, but can also cause changes in antioxidative enzymes. From the results, it was concluded that BC has a protective effect against Abeta -induced cytotoxicity in cultured astrocyte cells through the inhibition of lipid peroxidation and protection of antioxidative enzymes.

Amyloid beta-Peptides↗
PubMed2001

Differential distribution of ganglioside GM3 in seminiferous tubule and epididymis of adult rats.

Gangliosides are ubiquitous membrane components in mammalian cells and are suggested to play important roles in various functions such as cell-cell interaction, adhesion, cell differentiation, growth control and signaling. Among all ganglio-series gangliosides, GM3 has the simplest carbohydrate structure, and has been shown as a major ganglioside in male reproductive system. To study GM3 distribution in the seminiferous tubule and epididymis, frozen sections were stained with specific monoclonal antibody (MAb) against ganglioside GM3. In the seminiferous tubule of testis, pachytene spermatocytes and spermatids expressed ganglioside GM3, but not in spermatogonia and sertoli cells. Spermatogonia and sertoli cells near the basement membrane were negatively reacted to anti-GM3. In the epididymis, GM3 was expressed only in some interstitial cells. Taken together, these results suggest that the expression of ganglioside GM3 in rat seminiferous tubule and epididymis is spatio-temporally regulated during spermatogenesis.

Animals↗
PubMed2001

Inhibition of nitric oxide synthesis increases apoptotic cardiomyocyte death and myocardial angiotensin-converting enzyme gene expression in ischemia/reperfusion-injured myocardium of rats.

Cardiomyocyte apoptosis is an important pathogenic mechanism in myocardial ischemia/reperfusion (I/R) injury. It has been shown that nitric oxide (NO) and the renin-angiotensin system (RAS) are closely related, and both systems regulate apoptotic cell death. However, the effects of NO modulation on myocardial apoptotic cell death and changes in the RAS in the I/R-injured myocardium have not been studied. Female Sprague-Dawley rats were randomized into three groups: NO synthesis inhibitor, N(G)-nitro-L-arginine-methyl ester (L-NAME, 10mg/kg); NO precursor, L-arginine (540mg/kg); and vehicle. The rats were then subjected to 45 min coronary occlusion followed by 4 h reperfusion. The TdT-mediated in situ nick and labeling (TUNEL) indices were 39.9%+/-0.8% at the border and 30.9%+/-1.2% at the center of the I/R area in the vehicle group. L-NAME administration significantly increased these TUNEL-positive cells to 45.3%+/-1.9% and 37.9%+/-1.3%, respectively (P < 0.05 each). L-arginine administration reduced the TUNEL index at the border zone with marginal significance (P = 0.08 vs vehicle group). I/R injury significantly reduced the angiotensin-converting enzyme (ACE) mRNA expression in the left (ventricular) free wall of vehicle group rats. However, ACE mRNA expression was 1.9 times greater in the L-NAME group than that in the vehicle group (P < 0.05). This study showed that the inhibition of NO synthesis increased apoptotic cardiomyocyte death and local ACE mRNA expression in the I/R-injured myocardium. Our observations indicate that NO, ACE, and apoptotic cardiomyocyte death are related to each other during I/R injury.

Animals↗
PubMed2001

Current status of the anticoagulant hirudin: its biotechnological production and clinical practice.

Hirudin is a potent thrombin inhibitor originally derived from the medicinal leech, Hirudo medicinalis. Owing to its high affinity and specificity for thrombin, hirudin has been intensively investigated for research and therapeutic purposes. The investigation of hirudin has contributed greatly to the understanding of the mode of action of thrombin and the clotting system. Hirudin and several hirudin analogues have also been demonstrated to have several advantages as a highly specific anticoagulant over the most widely used drug, heparin. Due to the great demand for hirudin in physicochemical and clinical studies, various recombinant systems have been developed, using bacteria, yeasts, and higher eukaryotes, to obtain the biologically active hirudin in significant quantities. After 10 years of clinical applications, two recombinant hirudins and a hirudin analogue have gained marketing approval from the United States Food and Drug Administration, for several applications. Clinical trials are currently ongoing for other treatments for thrombotic disease. As a consequence, it is conceivable that hirudin may expand its therapeutic utility over heparin in the near future.

Amino Acid Sequence↗
PubMed2001

Case report: diabetic muscle infarction presenting as knee arthralgia.

Diabetic muscle infarction is a rare complication of diabetes and has characteristic clinical features including acute onset of pain with painful swelling, most commonly in the thigh or calf muscle, which gradually improves to complete resolution. Recently we experienced a case of diabetic muscular infarction presenting as knee joint pain due to involvement of the proximal portion of the leg muscle, which site has not been reported previously. This case shows that diabetic muscle infarction may involve sites other than the thigh and calf areas and should be considered in the differential diagnosis of knee arthralgia.

Aged↗