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Biomedical subjects

S I Kim

Publications and source records attributed to S I Kim.

At least 145 records · Page 8Linked to original sources
PubMed1997

Modulation of protein kinase C activity in NIH 3T3 cells by plant glycosides from Panax ginseng.

The involvement of ginsenosides in the signal cascade that stimulates cellular growth was investigated. It was found that ginsenosides Rh1 and Rh2 extracted from the root of Panax ginseng inhibited cellular proliferation in NIH 3T3 fibroblasts. Both ginsenosides Rh1 and Rh2 effectively reduced phospholipase C activity resulting in a decrease in the intracellular level of diacylglycerol, an endogenous activator of protein kinase C. The treatment of cells with Rh1 or Rh2 was thus found to reduce intracellular protein kinase C activity. We also observed that the phosphorylation of myristoylated alanine-rich C kinase substrate, one of the major substrates of protein kinase C in cells, was inhibited by the ginsenosides. Data suggest that the ginsenoside Rh1 or Rh2 exerts antiproliferative effects by inhibiting phospholipase C, which produces second messengers necessary for the activation of protein kinase C.

3T3 Cells↗
PubMed1997

Protection of rat liver microsomes against carbon tetrachloride-induced lipid peroxidation by red ginseng saponin through cytochrome P450 inhibition.

A possible role of cytochrome P450 (P450) inhibition by red ginseng saponins in carbon tetrachloride (CCl4)-induced lipid peroxidation was investigated in liver microsomes prepared from male Sprague Dawley rats. The total saponin of red ginseng standardized on ginsenosides-Rb1, -Rb2, -Rc, -Rd, -Re, and -Rg1 whose composition was studied in our previous report was used in the present study. The standardized saponin of red ginseng showed inhibitory effects on P450-associated monooxygenase activities in a dose-dependent manner, particularly p-nitrophenol hydroxylase activity which has been known to represent CCl4-activating P450 2E1 enzyme. Meanwhile, silymarin enhanced the activity of P450 2E1 enzyme in liver microsomes. When the lipid peroxidation was induced by incubating rat liver microsomes with CCl4 in the presence of NADPH, the standardized saponin significantly blocked the formation of thiobarbituric acid-reactive substances at the same concentrations showing P450 inhibition in liver microsomes. Silymarin revealed more potent protection against CCl4-induced lipid peroxidation. When the lipid peroxidation was induced by FeCl3, in which metabolic activation may not be required, only silymarin could protect the lipid peroxidation in liver microsomes. Taken together, our present results indicated that the inhibitory effects of red ginseng saponin on P450 enzymes may have a critical role in CCl4-induced lipid peroxidation in rat liver microsomes and that the mechanism of hepatoprotection by red ginseng saponin may be distinct from that of silymarin.

Animals↗
PubMed1997

Cloning and characterization of two catA genes in Acinetobacter lwoffii K24.

Two novel type I catechol 1,2-dioxygenases inducible on aniline media were isolated from Acinetobacter lwoffii K24. Although the two purified enzymes, CD I1 and CD I2, had similar intradiol cleavage activities, they showed different substrate specificities for catechol analogs, physicochemical properties, and amino acid sequences. Two catA genes, catA1 and catA2, encoding by CD I1 and CD I2, respectively, were isolated from the A. lwoffii K24 genomic library by using colony hybridization and PCR. Two DNA fragments containing the catA1 and catA2 genes were located on separate regions of the chromosome. They contained open reading frames encoding 33.4- and 30.4-kDa proteins. The amino acid sequences of the two proteins matched well with previously determined sequences. Interestingly, further analysis of the two DNA fragments revealed the locations of the catB and catC genes as well. Moreover, the DNA fragment containing catA1 had a cluster of genes in the order catB1-catC1-catA1 while the catB2-catA2-catC2 arrangement was found in the catA2 DNA fragment. These results may provide an explanation of the different substrate specificities and physicochemical properties of CD I1 and CD I2.

Acinetobacter↗
PubMed1997

A nuclear genetic lesion affecting Saccharomyces cerevisiae mitochondrial translation is complemented by a homologous Bacillus gene.

A novel Bacillus gene was isolated and characterized. It encodes a homolog of Saccharomyces cerevisiae Pet112p, a protein that has no characterized relative and is dispensable for cell viability but required for mitochondrial translation. Expression of the Bacillus protein in yeast, modified to ensure mitochondrial targeting, partially complemented the phenotype of the pet112-1 mutation, demonstrating a high degree of evolutionary conservation for this as yet unidentified component of translation.

Bacillus subtilis↗
PubMed1997

Decreased tumour necrosis factor-beta production in TNFB*2 homozygote: an important predisposing factor of lupus nephritis in Koreans.

Low TNF production and its association with TNF gene restriction fragment length polymorphism (RFLP) was demonstrated in (NZW/NZB) F1 mice. However, little is known about the significance of TNF production in association with TNF gene polymorphism in human SLE. This study was designed to evaluate the role of TNF production of peripheral blood mononuclear cells (PBMC) and its association with TNFB gene polymorphism in SLE, particularly lupus nephritis. TNFB gene polymorphism was defined by PCR-NcoI RFLP. TNF productions of phytohemagglutinin (PHA)-stimulated PBMC and T cells were examined by bioassay using L929 cell line and ELISA. The PBMC stimulated by PHA from patients with SLE (n = 60) tended to secrete less amounts of TNF by bioassay (1032 +/- 184 pg/ml vs 1524 +/- 224 pg/ml, P = 0.094), and TNF-beta by ELISA (P = 0.0082) than that from normal controls (n = 38). The low TNF-alpha producer was more frequent in nephritis than non-nephritis (34.4% vs 7.1% respectively, P < 0.01). TNF-beta also revealed similar results (53.1% vs 21.4%, P < 0.05). In SLE, mean production of TNF-beta was decreased in TNFB*2 homozygote (n = 18) than that in TNFB*1 homozygote (n = 9) (1126.3 +/- 145 pg/ml) vs 642 +/- 118.4 pg/ml, respectively, P = 0.021), whereas TNF-alpha production showed little difference between the two groups (710.1 +/- 56.4 vs 542.4 +/- 71.1 pg/ml, respectively, P = 0.149). Our results demonstrate that decreased TNF production of PBMC, which was significantly associated with TNFB*2 homozygosity, could be an important predisposing factor of lupus nephritis in Koreans.

Alleles↗
PubMed1997

A new suggestion for the treatment of minimally displaced fractures of the greater tuberosity of the proximal humerus.

Fourteen shoulders in 14 patients with minimally displaced fractures of the greater tuberosity of the proximal humerus were evaluated, at an average of 3 years, 7 months (range: 1 year to 6 years, 1 month) after the operation. For comparison this portion of the proximal humerus was measured using 100 Korean adult cadaveric humeri. The results of these preliminary studies suggest that the patients presenting with a one-part fracture of the greater tuberosity of the proximal humerus should be evaluated individually. In most patients in whom the displacement of the fragment is less than 5 mm, good results can be obtained with non-operative treatment. If the displacement of the fragment is more than 5 mm in young active patients, and more than 3 mm in individuals (especially athletes and heavy laborers) involved in overhead activity, the fragment should be mobilized, repaired, and fixed into its original bed or slightly inferolaterally.

Adult↗
PubMed1997

Results of kidney transplantation from 1979 to 1997 at Yonsei University.

1. Long-term graft survival markedly improved after the introduction of CsA as the main immunosuppressant in living-donor kidney transplantation at our institution. 2. HLA-identical LRD kidney transplantation provided the best long-term graft survival rate, probably due to a decreased incidence of graft loss from rejection. 3. We could achieve good long-term graft survival in LURD kidney transplantation compared with that of HLA-haploidentical LRD kidney transplantation. 4. Because of the striking discrepancy between organ donation and the increasing demand for transplantation, distant relative donors and LURDs, including swap donors, should be considered as an alternative way to increase the number of available donors when accompanied by a careful evaluation process.

Adolescent↗
PubMed1996

Ginsenoside-Rh2 blocks the cell cycle of SK-HEP-1 cells at the G1/S boundary by selectively inducing the protein expression of p27kip1.

The mechanism of action by which ginsenoside-Rh2 (G-Rh2) suppresses the proliferation of SK-HEP-1 cells is reported. The results from flow cytometric analyses show that G-Rh2 arrested the cell cycle at the G1/S transition phase. The cyclin E-dependent kinase activity which had been immunoprecipitated with cyclin E-specific antibody was down-regulated in the cells in response to G-Rh2. The IC50 value required to down-regulate the kinase activity by 50% was approximately 0.75 microM. Immunoblotting analyses show that G-Rh2 selectively induced the expression of p27kip1 in a dose-dependent manner whereas it had no effect on the levels of cyclin E, cdk2, and p21WAF1. In addition, our data show that G-Rh2 reduced the protein levels of cdc25A at doses higher than 10 microM. Collectively, these data suggest that ginsenoside-Rh2 arrests the cell cycle at the G1/S transition phase by selectively inducing protein expression of p27Kip1 and, as a consequence, down-regulating cyclin E-dependent kinase activity.

Animals↗
PubMed1996

Asn-tRNA in Lactobacillus bulgaricus is formed by asparaginylation of tRNA and not by transamidation of Asp-tRNA.

In many organisms (e.g., gram-positive eubacteria) Gin-tRNA is not formed by direct glutaminylation of tRNAGln but by a specific transamidation of Glu-tRNAGln. We wondered whether a similar transamidation pathway also operates in the formation of Asn-tRNA in these organisms. Therefore we tested in S-100 preparations of Lactobacillus bulgaricus, a gram-positive eubacterium, for the conversion by an amidotransferase of [14C]Asp-tRNA to [14C]Asn-tRNA. As no transamidation was observed, we searched for genes for asparaginyl-tRNA synthetase (AsnRS). Two DNA fragments (from different locations of the L.bulgaricus chromosome) were found each containing an ORF whose sequence resembled that of the Escherichia coli asnS gene. The derived amino acid sequences of the two ORFs (432 amino acids) were the same and 41% identical with E.coli AsnRS. When one of the ORFs was expressed in E.coli, it complemented the temperature sensitivity of an E.coli asnS mutant. S-100 preparations of this transformant showed increased charging of unfractionated L.bulgaricus tRNA with asparagine. Deletion of the 3'-terminal region of the L.bulgaricus AsnRS gene led to loss of its complementation and aminoacylation properties. This indicates that L.bulgaricus contains a functional AsnRS. Thus, the transamidation pathway operates only for Gin-tRNAGln formation in this organism, and possibly in all gram-positive eubacteria.

Amino Acid Sequence↗
PubMed1996

In vitro induction of differentiation by ginsenoides in F9 teratocarcinoma cells.

The aim of this study was to determine the ability of the ginsenosides, extracts of Panax ginseng C.A. Meyer, to cause differentiation of F9 teratocarcinoma stem cells as a model system. F9 stem cells cultured in the presence of the ginsenosides together with dibutyryl cyclic AMP (dbcAMP) became parietal endoderm-like cells. Moreover, the expression of differentiation marker genes, such as laminin B1 and type IV collagen, was increased after treatment with the ginsenosides. Among the various purified ginsenosides, Rh1 and Rh2 were the most effective at causing differentiation of F9 cells. Since ginsenosides and glucocorticoid hormone have similar chemical structures, we examined the possibility of the involvement of a glucocorticoid receptor (GR) in the differentiation process induced by the ginsenosides. According to Southwestern blot analysis, a 94 kDa protein regarded as a GR was detected in F9 cells cultured in the medium containing the ginsenosides Rh1 or Rh2. In addition, F9 stem cells treated with the ginsenosides Rh1 or Rh2 and with RU486, a glucocorticoid antagonist with a high affinity for the GR, did not differentiate into endoderm cells morphologically, and the expression of laminin B1 gene was not induced in these cells. In a gel mobility shift assay, protein factors capable of binding to the glucocorticoid responsive element (GRE) specifically were detected in nuclear extracts of the ginsenoside-treated F9 cells. Moreover, overexpression of GR by cotransfection of GR expression vector and GRE-luciferase vector enhanced the transactivation activity of GRE promoter in the presence of ginsenosides Rh1 or Rh2 and was further augmented by dbcAMP. In addition, ginsenosides Rh1 and Rh2 bound to a GR assessed by whole-cell binding assay, even though the specific binding affinity was weaker compared to dexamethasone. Based on these data, we suggest that the ginsenosides Rh1 and Rh2 cause the differentiation of F9 cells and the effects of ginsenosides might be exerted via binding with a GR or its analogous nuclear receptor.

Animals↗
PubMed1996

Ginsenoside Rh4, a genuine dammarane glycoside from Korean red ginseng.

A genuine glycoside, named ginsenoside Rh4, was isolated from Korean red ginseng (Panax ginseng C. A. Meyer) through repeated column chromatography, and its chemical structure was established to be 6-O-beta-D-glucopyranosyldammar-20(22),24-diene-3 beta,6 alpha,12 beta-triol by spectral and chemical methods. The stereochemistry of a double bond at C-20(22) of ginsenoside Rh4 was characterized as (E) from a NOESY experiment in the 1H-NMR of the aglycone. Cytotoxic activities of ginsenoside Rh4 and its aglycone against cancer cell lines were evaluated by use of the SRB method.

Antineoplastic Agents, Phytogenic↗
PubMed1996

Lactobacillus bulgaricus asparagine synthetase and asparaginyl-tRNA synthetase: coregulation by transcription antitermination?

Genes encoding the ammonia-dependent asparagine synthetase (asnA) and asparaginyl-tRNA synthetase (asnS) have been cloned from Lactobacillus bulgaricus ATCC 11842. The nucleotide sequence suggests that asnA and asnS are organized as one operon and regulated by the tRNA-directed transcription antitermination mechanism (T. M. Henkin, Mol. Microbiol. 13:381-387, 1994).

Amino Acid Sequence↗
PubMed1996

Expression of two cDNAs encoding class I chitinases of rice in Escherichia coli.

Two cDNAs encoding class I chitinases of rice were expressed in Escherichia coli. The cDNAs were fused to the MS2-polymerase gene in an expression vector, pEx31. The fusion proteins, expressed under the control of the lambda PL-promoter, showed the chitinase activity independent of the existence of the hevein domain. The enzymatic hydrolysis of colloidal chitin by the fusion proteins showed that the proteins were endo-type enzymes.

Chitinases↗
PubMed1996

Bestatin analogue from Streptomyces neyagawaensis SL-387.

A bestatin analogue, (2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl-L-valine (AHPA-Val), from the culture filtrate of Streptomyces neyagawaensis SL-387 was obtained in a chemically defined medium containing DL-3-amino-3-phenylpropionic acid. AHPA-Val was 6 times (IC50 = 1.2 micrograms/ml) as strong as bestatin (IC50 = 7.0 micrograms/ml) against porcine kidney microsomal aminopeptidase N, and 4 times (5.6 micrograms/ml) as strong as bestatin (IC50 = 20.7 micrograms/ml) against aminopeptidase N of human metastatic fibrosarcoma HT1080. To the best of our knowledge, this is the first report on the microbial production of AHPA-Val.

Amino Acids↗