Search PubMed⌕ Search

Biomedical subjects

S I Kim

Publications and source records attributed to S I Kim.

At least 19 recordsLinked to original sources
PubMed2001

Enhanced absorption of insulin and (Asu(1,7))eel-calcitonin using novel azopolymer-coated pellets for colon-specific drug delivery.

The objective of this study was to estimate colon-specific delivery of insulin and (Asu(1,7))eel-calcitonin using novel azopolymer-coated pellets. In vitro drug-release experiments from the azopolymer-coated pellets containing fluorescein isothiocyanate dextran (MW 4400; FD-4) were carried out by the Japanese Pharmacopoeia (J.P.) XIII rotating basket method with some slight modifications. Little release of FD-4 from the pellets was observed in phosphate buffered saline. However, the release of FD-4 was markedly increased in the presence of rat cecal contents. The intestinal absorption of insulin and (Asu(1,7))eel-calcitonin after oral administration of the azopolymer-coated pellets containing these peptides with camostat mesilate was evaluated by measuring the hypoglycemic and hypocalcemic effects, respectively. A slight decrease in plasma glucose levels was observed following the oral administration of these pellets containing 12.5 IU of insulin compared with the same dose of insulin solution. Camostat mesilate, a protease inhibitor that is incorporated with insulin in these pellets, further decreased the plasma glucose levels in a dose-dependent manner. Similar results were also obtained with the oral administration of pellets containing (Asu(1,7))eel-calcitonin. These findings suggest that azopolymer-coated pellets may be useful carriers for the colon-specific delivery of peptides including insulin and (Asu(1,7))eel-calcitonin.

Administration, Oral↗
PubMed2000

An improved method for quantitative sugar analysis of glycoproteins.

Although there are numerous methods available to hydrolyze glycans utilizing strong acids, it all requires lengthy steps to obtain quantitative yield. We have developed a new simple one-step method for analysis of amino and neutral monosaccharides of glycoproteins quantitatively. Free monosaccharides were found to be stable during hydrolysis of glycans with 6 N HCI at 80 degrees C up to 2 h. Using this condition, analysis of free monosaccharides hydrolyzed from the bovine fetuin showed sugar composition of Gal: Man: GlcN: GaIN = 13.2: 11.0: 15.5: 2.6, which is closely matched with the reported value of 12.4: 9.6: 17.2: 2.7 (Townsend et al., ABRF News 8: 14, 1997). This method was shown to be applicable to varieties of well-characterized glycoproteins, erythropoietin, fibrinogen and soybean agglutinin. The amounts of sugars released under the condition were very close to the experimental values by other procedures or to the theoretical ones. This condition was found to be suitable for direct sugar analysis of fetuin, which have been immobilized onto polyvinylidene difluoride membrane. Based on these results, it support that the 6 N HCl/80 degrees C/2 h is the simplest method for quantitative analysis of monosaccharide composition of glycoproteins.

Amino Sugars↗
PubMed2000

Linear type azo-containing polyurethane as drug-coating material for colon-specific delivery: its properties, degradation behavior, and utilization for drug formulation.

A segmented polyurethane containing azo aromatic groups in the main chain was synthesized by reaction of isophorone diisocyanate with a mixture of m,m'-di(hydroxymethyl)azobenzene, poly(ethylene glycol) (Mn = 2000), and 1,2-propanediol. This polyurethane was soluble in various solvents and showed a good coating and film-forming property. A solution-cast film of this polyurethane was found to be degraded in a culture of intestinal flora with the azo group reduction to hydrazo groups, not to amino groups. The film degradation, therefore, was attributed to the decreased cohesive energy in the hydrazo polymer compared with that in the original azo polymer. Then, the drug pellets containing water-soluble drugs (ONO-3708 and OKY-046) were undercoated with (carboxymethyl)(ethyl)-cellulose and overcoated with the azo polymer in order to examine the drug-releasing profiles in the culture of intestinal flora. The releasing rate of drugs from these double-coating pellets was found to depend on the molecular weight and the composition of the polyurethane used as the overcoat as well as the hydrophilicity of the incorporated drugs. Since the polyurethane was glassy and its segment motion or conformational change is frozen, the structure change should be retarded even after partial reduction of the azo groups, resulting in the effective prevention of the drug leakage. These data suggested that the present azo-containing polyurethanes are applicable as coating material of drug pellets in a colon-targeting delivery system.

Colon↗
PubMed2000

Cloning, overexpression and purification of Bacillus subtilis elongation factor Tu in Escherichia coli.

To establish the overexpression and one-step purification system of Bacillus subtilis elongation factor-Tu (EF-Tu), the EF-Tu gene was amplified with or without own ribosome binding site (rbs) by PCR and the only PCR product without rbs was subcloned successfully. For the expression of the EF-Tu gene cloned after PCR amplification, a constitutive expression system and inducible expression system with His6 tag at N-terminus or C-terminus, or glutathione-S-transferase (GST) fusion system were examined in E. coli and B. subtilis. Except GST fusion system in E. coli, however, all other trials were unsuccessful at the step of plasmid construction for the EF-Tu expression. The GST/EF-Tu fusion proteins were highly expressed by IPTG induction and obtained as both soluble and insoluble form. From the soluble GST/EF-Tu fusion protein, EF-Tu was obtained to near homogeneity by one-step purification with glutathione-sepharose affinity column chromatography followed by factor Xa treatment. The purified EF-Tu showed high GDP binding activity. These results indicate that the GST/EF-Tu fusion system is favorable to overexpression and purification of B. subtilis EF-Tu.

Bacillus subtilis↗
PubMed2000

Synthesis and characterization of stereospecific 1-propargyl-2-(dimethoxymethyl)-1-cyclohexanols.

Stereochemical isomers with hydroxy groups were synthesized by reacting 2-(dimethoxymethyl)cyclohexanone with propargylmagnesium bromide. The stereo chemical structures were identified by NMR spectral interpretation and the geometry optimization. To assist the NMR interpretation, geometry optimization based on semi-empirical AM1 and PM3 methods was applied. Throughout this study, the structures of the two isomers were all determined and 1H and 13C NMR spectra were fully assigned. It was proven that the less polar isomer is an axial alcohol and the more polar one is an equatorial alcohol.

Alkynes↗
PubMed2000

Differential expression of protein kinase C subtypes during ginsenoside Rh2-lnduced apoptosis in SK-N-BE(2) and C6Bu-1 cells.

We examined the modulation of protein kinase C (PKC) subtypes during apoptosis induced by ginsenoside Rh2 (G-Rh2) in human neuroblastoma SK-N-BE(2) and rat glioma C6Bu-1 cells. Apoptosis induced by G-Rh2 in both cell lines was confirmed, as indicated by DNA fragmentation and in situ strand breaks, and characteristic morphological changes. During apoptosis induced by G-Rh2 in SK-N-BE(2) cells, PKC subtypes alpha, beta and gamma were progressively increased with prolonged treatment, whereas PKC delta increased transiently at 3 and 6 h and PKC epsilon was gradually down-regulated after 6 h following the treatment. On the other hand, PKC subtype zeta markedly increased at 24 h when maximal apoptosis was achieved. In C6Bu-1 cells, no significant changes in PKC subtypes alpha, gamma, delta, epsilon and zeta were observed during apoptosis induced by G-Rh2. These results suggest the evidence for a possible role of PKC subtype in apoptosis induced by G-Rh2 in SK-N-BE(2) cells but not in C6Bu-1 cells, and raise the possibility that G-Rh2 may induce apoptosis via different pathways interacting with or without PKC in different cell types.

Animals↗
PubMed2000

Alterations in extracellular matrix components in transplant glomerulopathy.

The distribution pattern of extracellular matrix (ECM) components in transplant glomerulopathy was studied in relation to light microscopic features, actin expression of mesangial cells, and intraglomerular inflammatory cells. Nine cases of mild (group I) and nine cases of severe (group II) transplant glomerulopathy were stained with antisera against fibronectin (FN), tenascin (TN), collagen types III and IV, smooth muscle actin, CD45RO, CD68, and Ki-67 antigen. The composition of ECM was similar in the two groups. The expanded mesangium was diffusely stained by type-IV collagen, FN and TN, and focally and weakly stained by type-III collagen and smooth muscle actin. Type-IV collagen was linearly stained along the capillary walls, imparting a double-contour feature, whereas FN and TN showed granular staining along the capillary walls. CD68 positive cells were increased in severe transplant glomerulopathy, but this increase was not related to ECM deposition. These findings suggest that increased glomerular deposition of normal and abnormal ECM components participate in the evolution of transplant glomerulopathy.

Actins↗
PubMed2000

T-DNA insertional mutagenesis for functional genomics in rice.

We have produced 22 090 primary transgenic rice plants that carry a T-DNA insertion, which has resulted in 18 358 fertile lines. Genomic DNA gel-blot and PCR analyses have shown that approximately 65% of the population contains more than one copy of the inserted T-DNA. Hygromycin resistance tests revealed that transgenic plants contain an average of 1.4 loci of T-DNA inserts. Therefore, it can be estimated that approximately 25 700 taggings have been generated. The binary vector used in the insertion contained the promoterless beta-glucuronidase (GUS) reporter gene with an intron and multiple splicing donors and acceptors immediately next to the right border. Therefore, this gene trap vector is able to detect a gene fusion between GUS and an endogenous gene, which is tagged by T-DNA. Histochemical GUS assays were carried out in the leaves and roots from 5353 lines, mature flowers from 7026 lines, and developing seeds from 1948 lines. The data revealed that 1.6-2.1% of tested organs were GUS-positive in the tested organs, and that their GUS expression patterns were organ- or tissue-specific or ubiquitous in all parts of the plant. The large population of T-DNA-tagged lines will be useful for identifying insertional mutants in various genes and for discovering new genes in rice.

Base Sequence↗
PubMed2000

Effect of lovastatin on small GTP binding proteins and on TGF-beta1 and fibronectin expression.

We have shown that lovastatin, an inhibitor of 3 hydroxy-3-methylglutary coenzyme A (HMG CoA) reductase, delays development and progression of diabetic nephropathy in streptozotocine-induced diabetic rats through suppression of glomerular transforming growth factor (TGF)-beta1 mRNA expression. We have also shown that lovastatin suppresses both control and high glucose (HG)-induced TGF-beta1 and fibronectin mRNA expression and protein synthesis by rat mesangial cell (RMC) and that this down-regulation by lovastatin is reversed by mevalonate. It was postulated that this down-regulation may be linked to signaling of small guanine triphosphate (GTP)-binding proteins and mediated by the limitation of isoprenoids such as farnesylpyrophosphate (FPP) and geranylgeranylpyrophosphate (GGPP) in RMC. To determine the isoprenoid and small GTP-binding proteins involved in TGF-beta1 and fibronectin expression. FPP or GGPP was added alone or in combination to RMC treated with lovastatin cultured under normal or high glucose condition. Suppression of TGF-beta1 and fibronectin expression by lovastatin was reversed effectively when GGPP was added alone. Partial reversal of lovastatin effect on fibronectin and TGF-beta1 expression was found when FPP was added alone. Adding both GGPP and FPP resulted in complete reversal of lovastatin effect on fibronectin but not TGF-beta1 suggesting that fibronectin and TGF-beta1 are regulated differently. Furthermore, luciferase activity of RMC cotransfected with fibronectin promoter reporter system and plasmid-expressing C3 exoenzyme (a specific inactivator of Rho family GTP binding proteins, pEFC3) was completely suppressed when compared with RMC cotransfected with empty vector, pEF. Because geranylgeranylation is usually involved in post-translational modification and membrane targeting of Rho family small GTP binding proteins, these data indicate that Rho family small GTP-binding proteins rather than Ras family small GTP binding proteins may play a key role in the TGF-beta1 and fibronectin expression in RMC.

Animals↗