Biomedical subjects

C H Kim

Publications and source records attributed to C H Kim.

At least 271 records · Page 15Linked to original sources

PubMed1996

Zebrafish elav/HuC homologue as a very early neuronal marker.

Drosophila ELAV, a neuron-specific RNA binding protein, is expressed in all neurons right after their birth. This specific pattern of expression has led to its use as a pan-neuronal marker. At least three members of the elav family, HuD, HuC/ple21 and Hel-N1, have been reported to be neuron-specific in vertebrates, although it is unknown which member of this family is expressed at the time of early neuronal determination. We have isolated a zebrafish elav/HuC homologue (zHuC) which has 89% homology to human HuC protein. It is first expressed in the neuronal precursor cells in the neural plate immediately after gastrulation, and then high expression levels persist in most regions of the nervous system. HuC, like elav in Drosophila, may be one of the earliest neuronal markers in zebrafish.

Animals↗

PubMed1996

Dioxin activates human immunodeficiency virus-1 expression in chronically infected promonocytic U1 cells by enhancing NF-kappa B activity and production of tumor necrosis factor-alpha.

Dioxin, a prevalent environmental pollutant, is known to enhance replication of viruses in animals, but the mechanism is poorly understood. Here we report that dioxin triggers human immunodeficiency virus-1 (HIV-1) gene expression, resulting in increased production of HIV in chronically infected promonocytic U1 cells. This effect of dioxin is mediated, in part, via activation of nuclear factor kappa-B (NF-kappa B), a key cellular transcription factor that plays an important role in the induction of HIV genes and cytokine genes that regulate HIV-replication. Dioxin stimulated the production of tumor necrosis-alpha in U1 cells, and pentoxifylline, an inhibitor of TNF-alpha synthesis, inhibited dioxin induced HIV production and TNF-alpha. These studies provide a molecular and cellular basis for increased viral replication in cells exposed to dioxin.

Base Sequence↗

PubMed1996

Role of protein kinase C-beta isozyme in activation of latent human immunodeficiency virus type 1 in promonocytic U1 cells by phorbol-12-myristate acetate.

Protein kinase C (PKC) appears to play a role in replication of human immunodeficiency virus type 1 (HIV-1). PKC is a family of at least 12 isozymes. In this study, we investigated a role of Ca(2+)-dependent PKC isozymes (alpha, beta, and gamma) in activation of latent HIV-1 in U1, a chronically infected promonocytic cell line, using polyclonal rabbit anti-PKC isozyme antibodies as specific inhibitors. Antibodies were introduced intracellularly by electroporation and then cells were stimulated with PMA. HIV-1 production was measured as p24 antigen using ELISA and reverse transcriptase activity. Anti-PKC beta antibody significantly inhibited PMA-induced HIV-1 production, whereas antibodies against PKC alpha and gamma had no significant effect. Furthermore, anti-PKC beta antibody inhibited PMA-induced activation of NF-kappa B and HIV-1 LTR. Preincubation of anti-PKC beta antibody with its antigenic peptide reversed the inhibitory effect of anti-PKC beta antibody. This study suggest that PKC beta plays a role in PMA-induced activation of latent HIV-1.

Animals↗

PubMed1996

Sequence analysis of the 5'-flanking region of the gene encoding human N-acetylglucosaminyltransferase III.

We have isolated and characterized the immediate (1651 bP) 5'-flanking region of the gene (GnT-III) encoding N-acetylglucosaminyltransferase III (GnT-III) from a human placental genomic library. Analysis of promoter elements shows a similarity to the 5'-flanking region of murine 1,4-galactosyltransferase. The sequence lacks obvious TATA elements and CCAAT boxes; however, putative regulatory sites, including 2 potential cAMP-response regulatory elements (CRE), 11 insulin-response element consensus sequences (IRE), 7 potential AP-2 binding sites, 2 SP1 consensus sequences (GC boxes) and 2 sequences similar to the half-palindromic glucocorticoid-responsive element (GRE), are present.

Amino Acid Sequence↗

PubMed1996

Purification and biochemical characterization of pullulanase type I from Thermus caldophilus GK-24.

A thermostable pullulanase (pullulan 6-glucanohydrolase, EC 3.2.1.41) has been purified to homogeneity from Thermus caldophilus GK-24 by chromatographic methods, including gel-filtration and ion-exchange chromatography. The specific activity of the enzyme was increased 431-fold with a recovery of 13.2%. The purified enzyme was a monomer, M(r) = 65 kDa as estimated by SDS-PAGE and gel filtration. The pI was 6.1. The enzyme was most active at pH 5.5. The activity was maximal at 75 degrees C and stable up to 95 degrees C for 30 min at pH 5.5. The enzyme was stable to incubation from pH 3.5 to pH 8.0 at 4 degrees C for 24 h. The activity of the enzyme was stimulated by Mn2+ and Mg2+ ions. Ni2+, Ca2+, Co2+ ions and EDTA did not inhibit the enzyme activity. The enzyme hydrolyzed the alpha-1,6 linkages of amylopectin, glycogens, alpha, beta-limited dextrin, and pullulan. The enzyme caused the complete hydrolysis of pullulan to maltotriose. The activity was inhibited by alpha-, beta-, or gamma-cyclodextrins. The N-terminal sequence [(AIa-Pro-Gln-(Asp or Tyr)- Asn-Leu-Leu-Xaa-ILe-Gly-Ala(Ser)] showed some similarity to those of bacterial pullulanases.

Amino Acid Sequence↗

PubMed1996

On the dynamics and conformation of the HA2 domain of the influenza virus hemagglutinin.

To investigate the dynamics and conformation of the membrane-interacting HA2 domain of the hemagglutinin protein of influenza virus, the peripheral part of the HA2 domain (aa 1-127) was expressed in Escherichia coli. Four consecutive single-cysteine mutants, F63C, H64C, Q65C, and I66C, were generated using site-directed mutagenesis. This region is proposed to undergo a conformational change from a loop to a helical coiled-coil when going from the native to the fusion-active state [Bullough et al. (1994) Nature (London) 371, 37-43]. In the trimeric coiled-coil geometry positions 63 and 66 belong to the core so that cysteines from individual monomers are spatially close. On the other hand, positions 64 and 65 face the aqueous phase so that cyteines from monomers are spatially remote. The mutants were studied with cysteine-cysteine cross-linking and the spin-labeling electron paramagnetic resonance (EPR) in both the membrane-bound state and in the detergent-solubilized state. Extensive intramolecular cysteine-cysteine cross-linking was observed not only for F63C and I66C but also for H64C. Rates of cross-linking were comparable for these three mutants at physiological temperatures. These results are inconsistent with what is expected for a well-defined coiled-coil and suggest that the region containing the mutation sites is flexible. However, a characteristic cross-linking pattern consistent with a well-defined coiled-coil developed at very low temperatures. Line shapes of EPR spectra also indicate that this region is dynamic at ambient temperatures. Such flexibility perhaps arises from an equilibrium between a coiled-coil and a random coil conformation. No significant changes of the EPR spectra were observed upon lowering the pH to fusogenic conditions, suggesting that this flexible structure is the stable conformation at both neutral and low pH. The dynamic flexibility of this region may have important implications for the mechanism of HA-induced membrane fusion; for example it may be required for the apposition of the viral and endosomal membranes.

Circular Dichroism↗

PubMed1996

Presentation of the hydrophilic domains of hepatitis C viral E2 envelope glycoprotein on hepatitis B surface antigen particles.

Subviral particles of hepatitis B virus have been used to present foreign epitopes. We attempted to present the hydrophilic domains of E2 envelope protein of hepatitis C virus (HCV) as a fusion protein with hepatitis B virus surface antigen (HBsAg). The five hydrophilic domains of HCV E2 antigen were inserted into HBsAg such that the inserted hydrophilic domains were presented on the outer surface of HBV subviral particles. In addition, a fusion encoding the hypervariable region (HVR) of E2 antigen was also made. Cell lysate and culture medium were analyzed for the synthesis and secretion of the fusion proteins by immunoprecipitation with polyclonal anti-HBsAg antibody using recombinant vaccinia virus system. The results showed that the fusion proteins containing these six E2 domains were made in the cell, but only two out of six fusion proteins were secreted into culture medium. Further, cesium chloride density gradient analysis and electron microscopy revealed that these fusions were secreted into culture media as particles. It will be of interest to test immunogenicity of the HBsAg fusion particles containing the HCV E2 domains in animal model.

Amino Acid Sequence↗

PubMed1996

A prospective psychological evaluation of patients with dysphagia of various etiologies.

We hypothesized that patients who complain of dysphagia without demonstrable organic abnormality may have an underlying psychological dysfunction. We thus conducted a comprehensive assessment in three groups of patients with dysphagia. Dysphagia was classified as obstructive (Obst) when an obstructive lesion was present on esophagoscopy or barium swallow, motility-related (Mot) when abnormal motility was shown on esophageal manometry in the presence of normal esophagoscopy or barium swallow, or nonobstructive, nonmotility-related (NONM) when manometry and esophagoscopy or barium swallow were both normal. We prospectively evaluated 71 patients with Obst-dysphagia, 15 patients with Mot-dysphagia and 10 patients with NONM-dysphagia with a battery of standardized psychological tests including the Minnesota Multiphasic Personality Inventory (MMPI), the Symptom Checklist-90-Revised (SCL-90-R), and the Millon Behavioral Health Inventory (MBHI). The results indicate that patients with NONM-dysphagia have psychological attributes similar to those found in patients with Obst-dysphagia or Mot-dysphagia. Combination of scores for parameters such as somatization, depression, and anxiety could not distinguish among the three groups of dysphagia patients. We thus conclude that patients with NONM-dysphagia, as a group, have similar psychological profiles compared to patients with dysphagia due to organic causes.

Adult↗

PubMed1996

Simultaneous program of natural-cycle in vitro fertilization and cryopreserved-thawed embryo transfer.

PURPOSE: This clinical study was designed to identify and compare the pregnancy rates of simultaneous program of natural-cycle IVF and cryopreserved-thawed ET (NICE) with those of natural-cycle IVF and cryopreserved-thawed ET. METHODS: All three groups comprised spontaneously ovulating infertile women under the age of 40 and without any male factor present. The NICE program was performed in 36 patients (47 cycles) who had previously undergone IVF-ET resulting in cryopreserved embryos. As control groups, the natural-cycle IVF was performed in 45 patients (80 cycles), and the cryopreserved-thawed ET alone in 29 patients (40 cycles). RESULTS: The cancellation rate of the initiated cycles prior to ET was 19.1% (9/47) in the NICE group, 23.8% (19/80) in the natural-cycle IVF group, and 2.5% (1/40) in the cryopreserved-thawed ET group. The mean number of embryos transferred was 4.0 +/- 1.1 (2-5) in the NICE group, 1.0 in the natural-cycle IVF group, and 4.2 +/- 1.8 (1-5) in the cryopreserved-thawed ET group. The clinical pregnancy rates per aspiration cycle (32.5%) and per ET cycle (34.2%) in the NICE group were significantly higher than those (14.9, 16.4%) in the natural-cycle IVF group. The clinical and delivered pregnancy rates per ET (34.2, 26.3%) in the NICE group were higher than those (20.5, 15.4%) in the cryopreserved-thawed ET group, without statistical significance. CONCLUSIONS: Since the NICE program results in saving the fresh oocyte for patients participating in cryopreserved-thawed ET, more favorable pregnancy rates may be obtained from NICE cycles in women ovulating normally who had previously undergone IVF-ET with embryo cryopreservation.

Adult↗

PubMed1996

Neuron-specific expression of a chicken gicerin cDNA in transient transgenic zebrafish.

Gicerin, a novel cell adhesion molecule which belongs to the immunoglobulin superfamily, is expressed temporally and spatially in the developing chick brain and retina. The previous in vitro experiments using transfected cells showed that gicerin can function as a cell adhesion molecule which has both homophilic and heterophilic binding activities. For the in vivo analyses of gicerin in neural development, we tried to utilize a zebrafish system, a vertebrate suitable for studying early development. We generated transient transgenic animals by microinjecting DNA constructs into zebrafish embryos. Chicken gicerin, under control of the neurofilament gene promoter, was preferentially expressed in neuronal cells and gicerin-expressing neurons exhibited a fasciculation formation with neighboring gicerin-positive axons, which may be partly due to homophilic cell adhesion activity of gicerin. These experimental results suggest that this fast and efficient transgenic animal system is useful for studying the functional roles of neuron-specific genes during the development.

Animals↗

PubMed1996

Biotransformation of uridine monophosphate (UMP) and glucose to uridine diphosphate-glucose (UDPG) by Candida saitoana KCTC7249 cells.

The present study investigates the biotransformation of glucose with uridine monophosphate (UMP) to obtain sugar nucleotide, UDP-glucose (UDPG), by the dried cells of Candida saitoana KCTC7249. The biotransformation was optimized by varying the concentrations of substrates and phosphate ion. UDPG (24 mM) was biotransformed from 200 mM glucose and 37.5 mM UMP by dried cells of C. saitoana. The glucose yields about 64% UDP-glucose, based on UMP concentration. The addition of glucose-1-phosphate to the reaction mixture accelerated the formation of UDPG from a concentration of UMP. The structure of UDP-glucose obtained was determined with 13C NMR and FAB mass spectra. These results indicate that the yeast-dried cells could be used for the production of nucleotide sugars for donor molecules of complex carbohydrate synthesis.

Candida↗

PubMed1996

Nasogastric enteral feeding in the management of hyperemesis gravidarum.

OBJECTIVE: To report our experience in treating hyperemesis gravidarum with nasogastric enteral feeding. METHODS: Seven women (ages 17-36 years, mean 27 years) presented with intractable nausea, vomiting, dehydration, and weight loss (mean 13 lb) and were hospitalized for management of symptoms and nutritional support. An 8-Fr Dobbhoff nasogastric feeding tube was placed and nutritional supplement was administered as a continuous infusion, starting at a rate of 25 mL/hour. The rate of infusion was increased in an incremental fashion until daily caloric requirements were met. RESULTS: Nausea and vomiting improved within 24 hours after nasogastric tube placement. Enteral feedings were well tolerated, and all patients were discharged from the hospital within 8 days. Enteral feedings were continued, in an outpatient setting, for a mean of 43 days (range 5-174). Ultimately, all patients resumed oral feeding and discontinued enteral feeding. Subsequently, all patients gave birth to full-term, normal-weight babies. CONCLUSION: Enteral feeding via nasogastric tube seems to be effective in relieving intractable nausea and vomiting and in providing adequate nutritional support. Enteral nutrition should be considered as an alternative to total parenteral nutrition in the management of hyperemesis gravidarum.

Adult↗

PubMed1996

The efficacy of immunotherapy in patients who underwent superovulation with intrauterine insemination.

OBJECTIVE: To determine if the immunotherapy with corticosteroids would improve pregnancy rate in infertile patients with ovulatory factor and patients with unexplained infertility who undergo superovulation with IUI. DESIGN: Prospective, controlled study. SETTING: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Ulsan, Seoul, Korea. PATIENTS: Nine-one infertile patients with ovulatory factors and 78 patients with unexplained infertility who underwent superovulation with IUI. RESULTS: The prevalence of autoantibodies (antinuclear antibody, lupus anticoagulant, anticardiolipin antibody, antidouble-stranded DNA antibody) was elevated significantly in patients with unexplained infertility compared with patients with ovulatory infertility (20.5% versus 3.3%). Forty-five patients with ovulatory factor underwent 72 cycles of superovulation with IUI, receiving corticosteroids. Thirty-eight patients with unexplained infertility underwent 75 cycles of superovulation with IUI, receiving corticosteroids. Forty-six patients with ovulatory factor who underwent 66 cycles of superovulation with IUI and 40 patients with unexplained infertility who underwent 75 cycles of superovulation with IUI served as controls, not receiving corticosteroids. In patients with ovulatory factor, there were no significant differences between the corticosteroid treatment group and control group in clinical pregnancy rate (38.9% versus 33.3%) or in spontaneous abortion rate (14.3% versus 13.6%). In patients with unexplained infertility, there was a significantly higher clinical pregnancy rate per cycle in the corticosteroid treatment group, with 45.3% (34/75) compared with 29.3% (22/75) in the control group but no difference between the corticosteroid treatment and control groups in spontaneous abortion rate (17.6% versus 13.6%). There were no side effects due to the use of corticosteroids.

Adrenal Cortex Hormones↗

PubMed1996

Effect of decreasing plasma free fatty acids by acipimox on hepatic glucose metabolism in normal rats.

Increased availability of free fatty acids (FFA) may play a role in the pathogenesis of insulin resistance in the liver. We examined the effects of an antilipolytic nicotinic acid analog (acipimox) on hepatic glucose metabolism in basal and hyperinsulinemic states in normal rats. Acipimox decreased plasma FFA levels profoundly and enhanced the ability of insulin to suppress hepatic glucose production (HGP) and to stimulate peripheral glucose utilization. In the basal state, acipimox inhibited hepatic gluconeogenesis. However, this inhibition was not associated with the change in overall HGP due to the compensatory increase in hepatic glycogenolysis that might occur as a consequence of decreased hepatic glucose-6-phosphate (G-6-P) and/or plasma insulin levels with acipimox. These results support the contention that FFA are an important determinant of insulin action in the liver, and suggest the existence of intrahepatic autoregulatory and/or hormonal regulatory processes for constant HGP in the basal state.

Animals↗

PubMed1996

Effects of vitamin B12 on cell proliferation and cellular alkaline phosphatase activity in human bone marrow stromal osteoprogenitor cells and UMR106 osteoblastic cells.

Pernicious anemia has recently been recognized as one of the risk factors for osteoporosis and bone fractures, but the underlying pathophysiologic mechanism is still unknown. To determine whether vitamin B12 has any direct effect on osteoblasts, we studied the effects of vitamin B12 on the proliferation and alkaline phosphatase activity in human bone marrow stromal osteoprogenitor cells (hBMSC) and UMR106 osteoblastic cells. Vitamin B12 at concentrations as low as 10(-12) mol/L significantly stimulated [3H]-thymidine incorporation in both types of cells, but concentrations higher than 10(-12) mol/L did not produce a greater effect. Vitamin B12 in the concentration range from 10(-12) to 10(-8) mol/L concentration-dependently increased alkaline phosphatase activity in both hBMSC and UMR106 cells. Based on these results, we suggest that a suppressed activity of osteoblasts may contribute to osteoporosis and fractures in patients with vitamin B12 deficiency.

Alkaline Phosphatase↗

PubMed1996

C-type natriuretic peptide-mediated coronary vasodilation: role of the coronary nitric oxide and particulate guanylate cyclase systems.

OBJECTIVES: We tested the hypothesis that C-type natriuretic peptide (CNP) mediates coronary vasodilation through activation of cyclic guanosine monophosphate (cGMP) by way of particulate guanylate cyclase. BACKGROUND: CNP has known peripheral vasodilator properties, and preliminary data have suggested that it can function as a coronary vasodilator. METHODS: The actions of CNP were studied in instrumented dogs and in organ chamber rings in the presence and absence of a known antagonist to particulate guanylate cyclase, HS-142-1. Additionally, the actions of HS-142-1 were tested on acetylcholine-mediated coronary vasodilation, and immunohistochemical staining was utilized to localize the presence of CNP in the coronary endothelium. RESULTS: CNP relaxed isolated coronary arteries with (mean +/- SEM 45.9 +/- 7%*) and without (72.0 +/- 7%*) an endothelium (*p < 0.05 for CNP effect alone, p < 0.05 for endothelium vs. no endothelium with CNP). Intracoronary infusions increased coronary blood flow (baseline, 64.6 +/- 5.1 ml/min; CNP-5, 79.9 +/- 6.1*; CNP-20, 103.3 +/- 13.6* [*p < 0.05 vs. baseline value]) and reduced coronary vascular resistance (baseline, 1.6 +/- 0.3 mm Hg/ml per min; CNP-5, 1.4 +/- 0.3*; CNP-20, 1.2 +/- 0.3*). Intracoronary injections increased coronary blood flow (delta baseline coronary flow, 30 +/- 9* ml/min [*p < 0.05]). HS-142-1 significantly attenuated these increases (delta coronary flow, 30 +/- 9* ml/min [CNP] to 14 +/- 6 [CNP + HS-142-1] [p < 0.05 CNP vs. CNP + HS-142-1]) and the relaxation of organ chamber rings (56 +/- 7% [CNP] to 18 +/- 6% [HS-142-1 + CNP]). Finally, CNP was localized to the coronary endothelium and smooth muscle by immunohistochemical staining. CONCLUSIONS: CNP functions as a coronary vasodilator through activation of cGMP by way of particulate guanylate cyclase. CNP-mediated coronary vasodilation is attenuated by intracoronary HS-142-1. Intracoronary HS-142-1 does not affect acetylcholine-mediated coronary vasodilation. These observations support a role for exogenous CNP as a potent coronary vasodilator.

Animals↗

PubMed1996

Ca2+/calmodulin-dependent transcriptional activation of neuropeptide Y gene induced by membrane depolarization: determination of Ca(2+)- and cyclic AMP/phorbol 12-myristate 13-acetate-responsive elements.

Membrane depolarization stimuli (high potassium concentration and veratridine) increased neuropeptide Y (NPY) mRNA abundance time-dependently, without a change in beta-actin mRNA level, in NG108-15 and PC12 cells. Although the induction by veratridine was blocked completely by tetrodotoxin, the induction by potassium was suppressed minimally. Voltage-dependent Ca channel blockers and calmodulin antagonists inhibited the increases by both depolarization stimuli completely, suggesting involvement of Ca2+/calmodulin-dependent kinases (CaM kinases). Transient assay using chloramphenicol acetyltransferase reporter genes containing the rat NPY gene promoter indicated that membrane depolarization and Ca entry stimulate transcription of the NPY gene. The depolarization-induced transactivation was also blocked by CaM kinase inhibitors. The 200-bp 5'-upstream region (-344/-145) was localized as a Ca2+/ calmodulin-responsive element (CaMRE), which confers depolarization-induced transactivation. It is interesting that this CaMRE did not contain the canonical Ca-responsive elements such as CRE, SRE, NF-AT, or the C/EBP beta-binding site and was separated from a 64-bp cyclic AMP/ phorbol 12-myristate 13-acetate-responsive element (-144/-81). These findings suggested that membrane depolarization regulates the NPY gene transcription positively through the unique CaMRE by activation of CaM kinases following Ca entry through L-type Ca channels.

Animals↗

PubMed1996

Simplified ultralong protocol of gonadotrophin-releasing hormone agonist for ovulation induction with intrauterine insemination in patients with endometriosis.

The present study was designed to assess the usefulness of the simplified ultralong protocol of gonadotrophin-releasing hormone agonist (GnRHa) for ovulation induction with intrauterine insemination (IUI) in patients with various stages of endometriosis. A prospective randomized trial was set up to compare the simplified ultralong protocol (ULP) and the long protocol (LP) of GnRHa for ovulation induction with IUI in patients with endometriosis. There was no evidence of other factors in infertility in any patient. In the ULP group (39 patients), 4 weeks after a single injection of 3.75 mg Decapeptyl had been given, daily s.c. administration of 0.1 mg Decapeptyl was initiated and continued for at least 2 weeks prior to ovarian stimulation. In the LP group (41 patients), daily s.c. administration of 0.1 mg Decapeptyl was initiated from the mid-luteal phase of the cycle preceding the stimulation cycle. After 14 days of administration, ovarian stimulation was started if pituitary desensitization had been achieved. The amount of gonadotrophins required, number of days of gonadotrophin administration, serum oestradiol response, and the number of mature follicles were comparable in both groups. The clinical pregnancy rate per cycle was significantly higher in the ULP group at 48.7% (19/39) compared with 26.8% (11/41) in the LP group. The miscarriage rates were 21.1% (4/19) in the ULP group and 18.2% (2/11) in the LP group. In patients with stage I or II endometriosis, there was no significant difference between the two groups with respect to clinical pregnancy rate per cycle (47.4 versus 35.0%). In patients with stage III or IV endometriosis, the clinical pregnancy rate per cycle was significantly higher in the ULP group at 50.0% (10/20) compared with 19.0% (4/21) in the LP group. This study suggests that a simplified ULP of GnRHa could give better chances of achieving pregnancy in endometriosis patients undergoing assisted reproductive technologies and that this protocol may be more useful in patients with an advanced stage of endometriosis.

Adult↗