Biomedical subjects

S W Cho

Publications and source records attributed to S W Cho.

At least 91 records · Page 5Linked to original sources

PubMed1995

Two soluble forms of glutamate dehydrogenase isoproteins from bovine brain.

Two soluble forms of novel glutamate dehydrogenase isoproteins, designated GDH I and GDH II, have been purified from bovine brain. GDH I and GDH II were separated on a hydroxyapatite column and eluted by a step gradient at different phosphate concentrations (30 mM and 50 mM for GDH I and GDH II, respectively). The preparations were homogeneous on SDS/PAGE. GDH I and GDH II showed similarity in their molecular sizes and are composed of six identical subunits having a molecular size of 57,500 Da. Differences between the biochemical properties of GDH I and GDH II, such as N-terminal amino acid sequences of intact and tryptic-digested enzymes, kinetic parameters, optimum pH and heat stability, were extensively examined in both reductive amination of alpha-oxoglutarate and oxidative deamination of glutamate. The different effects of ADP on GDH isoproteins were also studied under various conditions. These results indicate that GDH I and GDH II, isolated from bovine brain, are novel and distinct polypeptides.

Adenosine Diphosphate↗

PubMed1995

Ginsenosides activate DNA polymerase delta from bovine placenta.

The activation of a DNA polymerase delta (pol delta) purified from bovine placenta by ginsenosides from Panax Ginseng C. A. Meyer has been studied. Preincubation of the enzyme with ginsenosides increased the polymerase activity 2.2-fold in a dose-dependent manner. There was a reproducible decrease in Km, in addition to a substantial increase in Vmax, in response to increasing concentrations of ginsenosides. Ginsenosides also activated the proofreading ability of 3'- to 5'-exonuclease activity associated with DNA pol delta. The coordinated activation of both polymerase and exonuclease activities of DNA pol delta by ginsenosides is consistent with the view that its polymerase and its exonuclease activities residue on the same protein molecule. UV/Vis difference spectroscopic studies suggested that the activation of DNA pol delta by ginsenosides might be due to the conformational change induced by ginsenosides binding.

Animals↗

PubMed1995

Production and characterization of monoclonal antibodies to bovine brain succinic semialdehyde reductase.

Monoclonal antibodies against bovine brain succinic semialdehyde reductase were produced and characterized. A total of nine monoclonal antibodies recognizing different epitopes of the enzyme were obtained, of which two inhibited the enzyme activity and three stained cytosol of rat spinal cord neurons as observed by indirect immunofluorescence microscopy. When unfractionated total proteins of bovine brain homogenate were separated by gel electrophoresis and immunoblotted, the antibodies specifically recognized a single protein band of 34 kDa, which comigrates with purified bovine succinic semialdehyde reductase. Using the antisuccinic semialdehyde reductase antibodies as probes, we investigated the cross-reactivities of brain succinic semialdehyde reductases from some mammalian and an avian species. The immunoreactive bands on western blots appeared to be the same in molecular mass--34 kDa--in all animal species tested, including humans. The result indicates that brain succinic semialdehyde reductase is distinct from other aldehyde reductases and that mammalian brains contain only one succinic semialdehyde reductase. Moreover, the enzymes among the species are immunologically very similar, although some properties of the enzymes reported previously were different from one another.

Animals↗

PubMed1995

Neutrophil chemotactic activities in bronchoalveolar lavage fluid from patients with bronchial asthma.

OBJECTIVES: To elucidate the presence of neutrophil chemotactic factor (NCF) and characterize them in the bronchial trees of symptomatic patients with bronchial asthma. METHODS: Bronchoalveolar lavage (BAL) fluids were concentrated by ultrafiltration. Differential counts of BAL cells was performed upto 500 cells on the cytocentrifuge-prepared slides. NCF activities in concentrated BAL fluids were measured by using microchemotactic chamber. These NCF activities were characterized by heat-stability, sensitivity to trysin and solubility into organic solvent. RESULTS: NCF activities were significantly higher in low molecular weight (LMW)-BAL fluid fraction below 5000 dalton than those in high molecular weight (HMW)-BAL fluid fraction. The NCF activities were significantly higher in the patients with bronchial asthma when compared to those of normal subjects. The LMW-NCF and HMW-NCF activities were correlated with the percentages of neutrophils in BAL fluid in the patients with bronchial asthma. The LMW-NCF activities were extractable into ether, stable to heat and resistant to trypsin. CONCLUSIONS: Main NCF activities in BAL fluid are suggested to be lipid substances with low molecular weight less than 5000 dalton and these substances may recruit neutrophils into the bronchial trees of patients with bronchial asthma.

Acetates↗

PubMed1995

A novel glutamate dehydrogenase from bovine brain: purification and characterization.

A soluble form of novel glutamate dehydrogenase has been purified from bovine brain. The preparation was homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and composed of six identical subunits having a subunit size of 57,500 Da. The biochemical properties of glutamate dehydrogenase such as N-terminal amino acids sequences, kinetic parameters, amino acids analysis, and optimum pH were examined in both reductive amination of alpha-ketoglutarate and oxidative deamination of glutamate. N-terminal amino acid sequences of the bovine brain enzyme showed the significant differences in the first 5 amino acids compared to other glutamate dehydrogenases from various sources. These results indicate that glutamate dehydrogenase isolated from bovine brain is a novel polypeptide.

Amino Acid Sequence↗

PubMed1994

Ruptured aneurysm of the sinus of Valsalva in a patient with Behçet's disease.

The vast majority of sinus of Valsalva aneurysm originated from a localized congenital defect of the aortic media and less frequently from infections or degenerative processes affecting the aortic wall. But aneurysm of sinus of Valsalva has not been reported up to the present in a patient with Behçet's disease. We report a 39-year-old woman presenting ruptured aneurysm of the sinus of Valsalva and Behçet's disease.

Adult↗

PubMed1994

Anaphora and branching direction in Japanese.

This paper constitutes a response to Lust & Mazuka's (1989) defence of the Principal Branching Direction parameter and their critique of O'Grady, Suzuki-Wei & Cho's (1986) experiment, which purported to show that even children learning left-branching languages exhibit a preference for forward patterns of anaphora. Results of new experimental work with children learning Japanese are reported and shown to support the claim that there is a universal preference for forward patterns of anaphora in the early stages of language acquisition.

Child, Preschool↗

PubMed1994

Differential effects of transforming growth factor-beta 1 and bone morphogenetic proteins in cultured rat osteogenic sarcoma and mink lung epithelial cells.

The effects of porcine bone morphogenetic protein (BMP) on DNA and collagen synthesis in cultured rat osteogenic sarcoma cells and mink lung epithelial cells were studied and compared with the effects induced by transforming growth factor-beta 1 (TGF-beta 1). In both cells, DNA synthesis was slightly but significantly increased by BMP whereas it was notably decreased by TGF-beta 1. The inhibitory action of TGF-beta 1 overrode the activation of DNA synthesis by BMP when the cells were incubated together with TGF-beta 1 and BMP. In osteogenic sarcoma cells, collagen synthesis was enhanced by both BMP and TGF-beta 1, but the stimulatory action of BMP was weaker than that of TGF-beta 1. In epithelial cells, TGF-beta 1 increased collagen synthesis but BMP induced no significant changes. No synergistic effects of TGF-beta 1 and BMP on collagen synthesis were observed in both cells. The present study demonstrates the possibility of direct actions of BMP and TGF-beta 1 on cultured rat osteogenic sarcoma cells and mink lung epithelial cells in vitro.

Animals↗

PubMed1993

Interleukin 1 beta regulates glycogen metabolism in primary cultured rat hepatocytes.

We examined the effects of human recombinant IL-1 beta on glycogen metabolism in cultured rat hepatocytes. When IL-1 beta was present at 8 nM in the culture medium for 15 hours prior to cell harvest, glycogen storage in hepatocytes was lowered approximately by 60% of the control. The enzymatic activity of glycogen synthase I in the IL-1 beta-treated cells (8 nM) was decreased by 70%; however, the activity ratio of the synthases I to D was not different from the untreated. In addition, the activity of glycogen phosphorylase a, the active form of phosphorylase involved in glycogenolysis, was increased by approximately 27% while the total phosphorylase activity was not changed. The data demonstrate for the first time that IL-1 beta lowers the intracellular glycogen contents in primary cultured rat hepatocytes.

Animals↗

PubMed1993

Kinetics and mechanism of an NADPH-dependent succinic semialdehyde reductase from bovine brain.

An NADPH-dependent succinic semialdehyde reductase has been purified from bovine brain by several chromatographic procedures. The preparation appeared homogeneous on SDS/PAGE. The enzyme is a monomeric protein with a molecular mass of 28 kDa. A number of properties of the bovine brain enzyme, such as substrate specificity, specific activity, molecular mass, optimum pH, amino acid composition, and kinetic parameters, have been determined and compared with those reported for preparations from other sources. The results indicate that the enzyme isolated from bovine brain in the present study is different from those reported for preparations from other sources. The inhibition kinetic patterns obtained when the products of the reaction or substrate analogs are used as inhibitor of the reaction catalyzed by the enzyme are consistent with an ordered sequential mechanism involving the formation of an intermediate ternary complex and in which NADPH is the first substrate to bind the enzyme.

Amino Acids↗

PubMed1992

Endoscopic application of Gianturco-Rösch biliary Z-stent.

Ginaturco-Rösch Z-stent is a new self-expanding stainless steel stent for drainage of the obstructed biliary system. It has been used only with a percutaneous transhepatic technique. We describe a new method for endoscopic retrograde placement of a Gianturco-Rösch biliary Z-stent. This report describes our experience for endoscopic application of a Gianturco-Rösch biliary Z-stent in a patient with a benign stricture and multiple common bile duct stones.

Aged↗

PubMed1991

Aluminum interrupts the formation of alkaline-ribonuclease-inhibitor complex from bovine brain.

The effect of aluminum on alkaline ribonuclease (RNase) and RNase inhibitor, purified from bovine brain, was investigated. Incubation of alkaline RNase with aluminum interrupted binding of RNase inhibitor to alkaline RNase. A stoichiometry of 1:1 for the binding of aluminum to brain alkaline RNase was estimated, whereas no aluminum was found to be bound to the RNase inhibitor. Aluminum-bound alkaline RNase, however, retained a full alkaline RNase activity. None of the enzyme-bound aluminum was dissociated by dialysis against 50 mM Hepes, pH 7.0, at 4 degrees C for 24 h. Citrate, EDTA, NaF and apotransferrin protected the alkaline RNase against aluminum binding. Aluminum did not bind to the incubated alkaline RNase-inhibitor complex, suggesting that aluminum might compete with RNase inhibitor for the binding site. However, the data from chemical modification and spectroscopic studies indicate that it is also highly possible that aluminum binding to the enzyme induces conformational changes at or near the inhibitor-binding site, which subsequently interrupt binding of RNase inhibitor to alkaline RNase. These results suggest that accumulation of aluminum in brain might affect the regulation of RNA metabolism.

Aluminum↗

PubMed1991

Primary adenoid cystic carcinoma of the esophagus: a case report.

We report on the case of a 61-year-old woman with a pedunculated esophageal tumor that had a central ulceration. Histology of the resected tumor revealed adenoid cystic carcinoma which was localized entirely in the submucosal layer. The tumor was composed predominantly of solid nests of tumor cells, with some areas showing a cribriform pattern.

Carcinoma, Adenoid Cystic↗

PubMed1991

Activation of acid ribonuclease from bovine brain by aluminum.

An acid ribonuclease (optimum pH 6.0) has been purified from bovine brain in a five-step procedure. The preparation appeared homogeneous on SDS-polyacrylamide gel electrophoresis. The molecular size of the acid ribonuclease is 70 kDa and it is a dimeric protein with a subunit molecular size of 35 kDa. The acid RNase was activated by aluminum at low concentration. Preincubation of the acid RNase with 10 microM increased the specific activity of the enzyme 2.3-fold at acid pH, while the effect of aluminum was much weaker at alkaline pH under otherwise the same conditions. A stoichiometry of 1: 1 for the binding aluminum to brain acid RNase was estimated. None of the enzyme-bound aluminum was dissociated by dialysis against 50 mM HEPES, pH 7.0 at 4 degrees C for 24 h. Citrate, EDTA, NaF, and apotransferrin abolished the effects of aluminum on the enzyme. Ribonucleic acid also protected the enzyme against the activation caused by aluminum. These results suggest that accumulation of aluminum in brain may change the regulation of ribonucleic acid metabolism.

Aluminum↗

PubMed1991

Silica granuloma: scanning electron microscopy and energy dispersive X-ray microanalysis.

A 46-year-old woman had 1-month-old erythematous papules on the left elbow and both knees where acupuncture with gold needles had been performed twenty years earlier. She also had a 2-month-old pruritic scar lesion on the nape. Histopathologic findings showed sarcoidal granulomas. The presence of silica components in the granulomas was confirmed by scanning electron microscopy (SEM) of the lesion on the nape and energy dispersive X-ray microanalysis (EDXA) of the lesions on the nape and the left elbow. We suggest that acupuncture with gold needles may be one cause of silica granuloma.

Acupuncture Therapy↗

PubMed1991

Characterization of three monoclonal antibodies to membrane co-factor protein (MCP) of the complement system and quantification of MCP by radioassay.

MCP is a widely distributed regulatory glycoprotein of the complement system which binds C3b and C4b and has factor I-dependent co-factor activity. Monoclonal antibodies raised to lymphocytes (E4.3), chorionic microvilli (GB24) and an embryonal carcinoma cell line (TRA-2-10) recognize MCP (CD46). GB24 inhibited both the binding of MCP to its ligand iC3 and co-factor activity; E4.3 and TRA-2-10 did not. The binding of GB24 to cells bearing MCP was not cross-inhibited by E4.3 or TRA-2.10, but TRA-2-10 blocked binding and displaced pre-bound E4.3. Using these antibodies, we developed a radioassay for quantifying the number of MCP molecules/cells. Human peripheral blood mononuclear (PBMC) and polymorphonuclear cells (PMN) had about 10,000 MCP cell; platelets had about 600/cell, and no MCP was found on erythrocytes. Neoplastic hematopoietic cell lines, of myelocytic and T lymphocytic origin, had several-fold more (20-60,000) molecules cell than peripheral blood cells or B cell lines (about 12,000). Malignant epithelial cell lines. HeLa (about 100,000/cell) and HEp-2 (about 250,000 cell) had the highest MCP expression of any cells examined. These monoclonal antibodies--especially GB24, which blocks MCP function--and the direct binding assay will facilitate the further analysis of the biology of this complement regulatory protein.

Antibodies, Monoclonal↗

PubMed1990

Saturation site-directed mutagenesis of thymidylate synthase.

We have subjected 12 different codons of a synthetic Lactobacillus casei thymidylate synthase (TS) gene to saturation site-directed mutagenesis to create amino acid "replacement sets" at each of those positions. The target residues were chosen because they are highly conserved and because they are important for the structure and function of the protein as indicated by solution and structural studies. The mutagenesis procedure involved excision of a fragment of the synthetic gene containing the target codon, followed by its replacement with a mixture of oligonucleotides which code for all 20 amino acids and the amber stop codon. TS mutants were identified by DNA sequencing, and catalytically active mutants were identified by genetic complementation using a Thy- strain of Escherichia coli. Only 3 of the 12 target amino acids examined were essential for TS activity; and of the 125 total mutants identified, 57 were catalytically active. These results point to a high degree of plasticity of TS in accommodating function with structural change.

Amino Acid Sequence↗

PubMed1990

Characterization of glucose-6-phosphate dehydrogenase isozymes from human and pig brain.

Homogenates of human and pig brain in 10 mM Tris-HCl, pH 8.0 were centrifuged at 25,400 x g for 1 h. The supernatants were electrophoresed in polyacrylamide gels were stained for glucose-6-phosphate dehydrogenase (EC 1.1.1.49) activity. Five distinct bands were visible. Isozymes corresponding to two of those bands were purified from human and pig brain. The isozymes were electrophoretically homogeneous. The native proteins, Mr, 220,000, dissociated in sodium dodecyl sulphate-polyacrylamide gels into a 57,000 Mr subunit. Therefore, the native isozymes are tetramers. None of the isozymes required additional metal ions for activity. At 1 mM concentration Mg2+ and Ca2+, independently or together, activated the isozymes 1.5-fold. The isozymes were NADP(+)-specific. Kmapp values of the G6PD isozymes were similar for NADP+ (6-8 microM), but different for G6P (56-180 microM). The specific activities of the isozymes varied from 50 to 210 units per mg of protein. All isozymes were inhibited by NADPH. The inhibition was competitive with respect to NADP+ and non-competitive with respect to G6P. NADH did not affect any of the isozymes. ATP inhibited the isozymes competitively with respect to G6P and non-competitively with respect to NADP+. Palmitoyl-CoA dissociated the active tetramers into enzymatically inactive dimeric forms. This treatment also abolished the 6-phosphogluconate activity of the isozyme II from both sources. High performance liquid chromatography peptide maps of the tryptic digest and amino acid analyses of the isozymes showed extensive homologies between the corresponding isozymes from the two species. Interestingly, only the isozyme II in human and pig brain was active with 6-phosphogluconate as a substrate (Kmapp = 864 and 279 microM). The specific activities of the isozyme II with 6-phosphogluconate (14 and 48 unit per mg of protein for human and pig brain isozyme II, respectively) was four times less than those with G6P. It is therefore suggested that isozyme II is a bifunctional enzyme.

Amino Acids↗