PubMed Health⌕ Search

Biomedical subjects

Kyung-Bok Lee

Publications and source records attributed to Kyung-Bok Lee.

17 recordsLinked to original sources
PubMed2006

Protein nanopatterns and biosensors using gold binding polypeptide as a fusion partner.

An efficient strategy for immobilizing proteins on a gold surface was developed by employing the gold binding polypeptide (GBP) as a fusion partner. Using the enhanced green fluorescent protein (EGFP), severe acute respiratory syndrome coronavirus (SARS-CoV) envelope protein (SCVme), and core streptavidin (cSA) of Streptomyces avidinii as model proteins, specific immobilization of the GBP-fusion proteins onto the gold nanoparticles and generation of protein nanopatterns on the bare gold surface were demonstrated. The GBP-fused SCVme bound to gold nanoparticles successfully interacted with its antibody and showed changes in absorbance and color, allowing efficient diagnosis of SARS-CoV. The fusion proteins could be successfully immobilized on the gold surface by nanopatterning and microcontact printing as examined by atomic force microscopy and surface plasmon resonance analysis. The poly(dimethylsiloxane) microfluidic channels were created on the gold surface and were used for antigen-antibody and DNA-DNA interaction studies. Specific immobilization of GBP-EGFP fusion protein and its interaction with the antibody in the microchannels could be demonstrated. By immobilizing the DNA probe through the use of GBP-fused cSA, specific hybridization of the target DNA prepared from Salmonella could also be achieved. The GBP-fusion method allows immobilization of proteins onto the gold surface without surface modification and in bioactive forms suitable for studying protein-protein, DNA-DNA, and other biomolecular interaction studies. Furthermore, these studies can be carried out in a microfluidic system, which allows high-throughput analysis of biomolecular interactions.

Biological Assay↗
PubMed2006

Quantification of human neural stem cell engraftments in rat brains using ERV-3 real-time PCR.

Few sensitive and reliable methods have been available for quantifying the number of transplanted human neural stem cells (hNSC) in the animal brain. To develop an accurate method for quantifying the number of hNSC incorporated in rat brain, we performed real-time PCR on hNSC-transplanted rat brains using a target sequence for ERV-3, which is an endogenous retrovirus present with a known copy number in all human cells, but not present in rodent cells. A standard curve was developed for known amount of different mixes of hNSC and rat fibroblasts, and test samples were prepared by manually incorporating variable, predefined numbers of hNSCs into rat brains. A cerebral rat hemisphere injected with 10(7) hNSC revealed 1.125% chimerism. Moreover, a linear correlation was found between hNSC numbers injected and their concentrations in the rat brain. In conclusion, the developed quantitative ERV-3 assay enables a simple, fast, and reproducible detection and quantitation of hNSC numbers in the rat brain.

Animals↗
PubMed2006

Immunosuppressive effects of rutaecarpine in female BALB/c mice.

Rutaecarpine is a major quinazolinocarboline alkaloid isolated from Evodia rutaecarpa. It was reported to possess a wide spectrum of pharmacological activities, such as vasodilation, antithrombosis, and anti-inflammation. In the present study, adverse effects of rutaecarpine on immune functions were determined in female BALB/c mice. Rutaecarpine had no effects on hepatotoxicity parameters in mice, as measured by serum activities of aminotransferases. Meanwhile, rutaecarpine significantly decreased the number of antibody-forming cells and caused weight decrease in spleen in a dose-dependent manner, when mice were administered with rutaecarpine at 10mg/kg, 20mg/kg, 40 mg/kg or 80 cmg/kg once intravenously. In addition, rutaecarpine administered mice exhibited reduced splenic cellularity, decreased numbers of total T cells, CD4(+) cells, CD8(+) cells, and B cells in spleen. IL-2, interferon-gamma and IL-10 mRNA expressions were suppressed significantly by rutaecarpine treatment. The number of CD4(+)IL-2(+) cells was reduced significantly following administration of mice with rutaecarpine. Furthermore, rutaecarpine caused the cell cycle arrest in G(0)+G(1) phase in a dose-dependent manner. Rutaecarpine caused significant inductions of hepatic cytochrome P450 (CYP) 1A, 2B, and 2E1 activities dose-dependently. In the splenic lymphocyte proliferation assay, rutaecarpine inhibited proliferation by LPS and Con A ex vivo, whereas it had no effects on in vitro proliferation. These results suggested that a single bolus intravenous injection of rutaecarpine from 20mg/kg might cause immunosuppressive effects, and that rutaecarpine-induced immunosuppression might be mediated, at least in part, through the inhibition of cytokine production and cell cycle arrest in G(0)+G(1) phase, and caused possibly by mechanisms associated with metabolic activation.

Alkaloids↗
PubMed2005

Micropatterning proteins on polyhydroxyalkanoate substrates by using the substrate binding domain as a fusion partner.

A novel strategy for micropatterning proteins on the surface of polyhydroxyalkanoate (PHA) biopolymer by microcontact printing (microCP) is described. The substrate binding domain (SBD) of the Pseudomonas stutzeri PHA depolymerase was used as a fusion partner for specifically immobilizing proteins on PHA substrate. Enhanced green fluorescent protein (EGFP) and red fluorescent protein (RFP) fused to the SBD could be specifically immobilized on the micropatterns of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). Laser scanning confocal microscopic studies suggested that two fusion proteins were micropatterned in their functionally active forms. Also, antibody binding assay by surface plasmon resonance suggested that protein-protein interaction studies could be carried out using this system.

Adsorption↗
PubMed2005

Granulocyte colony-stimulating factor induces sensorimotor recovery in intracerebral hemorrhage.

Granulocyte colony-stimulating factor (G-CSF) has been used in the treatment of neutropenia in hematologic disorders. The neuroprotective and anti-inflammatory effects of G-CSF were reported in various neurological disease models. In this study, we examined whether G-CSF induces functional recovery after intracerebral hemorrhage (ICH). ICH was induced using collagenase injection in adult rats. Either G-CSF (50 microg/kg, i.p.) or saline was given from 2 h after ICH and every 24 h for 3 days. 72 h after ICH induction, the rats were sacrificed for histological analysis and measurement of brain edema. Behavioral tests were performed before and 1, 7, 14, 21, 28, and 35 days after ICH. We also measured the blood-brain barrier (BBB) permeability using Evans blue dye injection method. G-CSF-treated rats recovered better on rotarod and limb placing tests, starting from 14 days throughout 5 weeks after ICH. The brain water content and BBB permeability of G-CSF-treated group decreased in the lesioned hemispheres compared with those of ICH-only group. In G-CSF-treated group, the number of TUNEL+, myeloperoxidase+, and OX42+ cells was smaller than that of ICH-only group in the periphery of hematoma. These findings suggest that G-CSF induces long-term sensorimotor recovery after ICH with reduction of brain edema, inflammation, and perihematomal cell death.

Animals↗
PubMed2005

Biomimetic micropatterning of silica by surface-initiated polymerization and microcontact printing.

Micropatterns of silica on a gold substrate were generated by a biomimetic approach, namely, the biosilicification of silicic acids. The procedure consists of three simple steps: pattern generation of a polymerization initiator, (BrC(CH(3))(2)COO(CH(2))(11)S)(2), by microcontact printing; surface-initiated, atom-transfer radical polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) from the patterned area; and polycondensation of silicic acids. The tertiary amine-containing polymer, pDMAEMA, aided in the spatially controlled polycondensation of silicic acids on surfaces in the presence of phosphate ions, and micropatterns of silica on a gold substrate were successfully generated in combination with the technique of microcontact printing. The procedure could be extended to the controlled fabrication of silica patterns with any size, shape, or thickness.

Biocompatible Materials↗
PubMed2005

beta-Secretase (BACE1) inhibitors from pomegranate (Punica granatum) husk.

In the course of screening for anti-dementia agents from natural products, two beta-secretase (BACE1) inhibitors were isolated from the husk of pomegranate (Punica granatum) by activity-guided purification. They were identified as ellagic acid and punicalagin with IC50 values of 3.9 x10(-6) and 4.1x10(-7) M and Ki values of 2.4x10(-5) and 5.9x10(-7) M, respectively. The compounds were non-competitive inhibitors with a substrate in the Dixon plot. Ellagic acid and punicalagin were less inhibitory to alpha-secretase (TACE) and other serine proteases such as chymotrypsin, trypsin, and elastase, thus indicating that they were relatively specific inhibitors of BACE1.

Acetates↗
PubMed2004

Biomimetic formation of silica thin films by surface-initiated polymerization of 2-(dimethylamino)ethyl methacrylate and silicic acid.

Biosilicification in diatoms is achieved by specific interactions between silaffins, composed of polypeptides and long-chain polyamines, and silicic acid derivatives. The polycondensation of silicic acids is reported to be catalyzed by the long-chain polyamines that mainly contain tertiary N-methylpropyleneimine moieties. In this report, we utilized a tertiary amine-containing polymer, poly(2-(dimethylamino)ethyl methacrylate) (poly(DMAEMA)), as a surface-grafted, biomimetic counterpart of the long-chain polyamines in silaffins and demonstrated that the surface-initiated polycondensation of silicic acids, leading to the formation of silica thin films, proceeded smoothly on surfaces presenting poly(DMAEMA), where poly(DMAEMA) was grown from gold surfaces by surface-initiated, atom transfer radical polymerization. The formed silica film was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy.

Gold↗
PubMed2004

Micropatterns of spores displaying heterologous proteins.

Micropatterns of Bacillus thuringiensis spores were generated by a combination of surface chemistry, microcontact printing, and spore surface display technique. The outermost layers of B. thuringiensis spores were engineered to present enhanced green fluorescent protein (EGFP), and the biospecific interaction between biotin and streptavidin was utilized to spatially direct the EGFP-presenting spores onto the micropatterned surfaces. The viability of the micropatterned spores was confirmed by the pattern generation of vegetative cells after the germination.

Bacillus thuringiensis↗
PubMed2004

Pattern generation of biological ligands on a biodegradable poly(glycolic acid) film.

The micropatterns of biological ligands (biotin and RGD peptides) were generated on a flat surface of biodegradable polymer, poly(glycolic acid) (PGA). The immobilization of biological ligands onto the surface of biodegradable polymers (especially aliphatic polyesters) is usually hampered by the absence of functionalizable groups on the polymer backbone. We demonstrate herein that PGA polymer films were modified by surface hydrolysis to introduce carboxylic acid groups on the film surfaces, which were subsequently used for patterning amine-terminated ligands by microcontact printing. Fluorescence microscopy was used to verify the pattern of biotin on the surface of the PGA films after complexation with fluorescein-conjugated streptavidin. In addition, the cellular micropatterns were obtained from micropatterns of RGD peptides on the surface-hydrolyzed PGA films.

Biodegradation, Environmental↗
PubMed2004

An antioxidant hispidin from the mycelial cultures of Phellinus linteus.

In the course of screening for reactive oxygen species scavengers from natural products, an antioxidant was isolated from the mycelial culture broth of Phellinus linteus and identified as hispidin. The hispidin content was reached its maximum level at 12 days after onset of inoculation. About 2.5 mg/mL of hispidin was produced by P. linteus in a yeast-malt medium (pH 5.8, 25 degrees C). Hispidin inhibited 22.6 and 56.8% of the super oxide anion radical, 79.4 and 95.3% of the hydroxyl radical, and 28.1 and 85.5% of the DPPH radical at 0.1 and 1.0 mM, respectively. The positive control alpha-tocopherol scavenged 25.6 and 60.3%, 74.6 and 96.3%, and 32.7 and 77.5% of each radical, respectively, at the same concentrations. However, hispidin showed no significant activity on the hydrogen peroxide radical.

Agaricales↗
PubMed2004

Effects of vitamin E on oxidative stress and membrane fluidity in brain of streptozotocin-induced diabetic rats.

BACKGROUND: Diabetics and experimental animal models exhibit high oxidative stress due to persistent and chronic hyperglycemia, thereby deplete the activity of the antioxidative defense system and thereby promote the generation of free radicals. The current study examined the effects of vitamin E on oxidative stress and membrane fluidity in the brain of diabetes-induced rats. METHODS: Sprague-Dawley male rats were randomly assigned to normal and streptozotocin (STZ)-induced diabetic groups. The diabetic groups were fed a vitamin E-free diet, 40 mg vitamin E/kg diet, or 400 mg vitamin E/kg diet. Diabetes was induced with STZ after 3 weeks of the experimental diet, then the rats were sacrificed 9 days later to determine the oxidative stress and cell membrane fluidity in the brain. RESULTS: Dietary vitamin E strengthened the antioxidative defense system with an increased activity of the antioxidant enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) and increased vitamin E content, in the brain of the diabetes-induced experimental rats. Accordingly, vitamin E was found to reduce the accumulation of reactive oxygen species (ROS), such as superoxide radical decrease the generation of oxidative damage substances, such as the carbonyl value, increase the membrane fluidity lowered by oxidative damage, and significantly improve the lipid composition. CONCLUSIONS: Vitamin E was found to be excellent for strengthening the antioxidative defense system, reducing the generation of ROS and damaging oxidative substances, and maintaining membrane fluidity in the brain of diabetes-induced rats.

Animals↗
PubMed2003

Surface modification of poly(glycolic acid) (PGA) for biomedical applications.

The immobilization of biological ligands (such as biotin and peptides) onto biodegradable polymer surfaces, including poly(glycolic acid) (PGA) sutures, is complicated by the absence of functional groups on the polymer backbone. We demonstrate a method for overcoming this problem, by attaching (+)-biotinyl-3,6,9-trioxaundecanediamine to the surface of PGA sutures, which immobilizes the ligand through an amide bond between amine (ligands) and carboxylic acid groups (surface-hydrolyzed PGA sutures). Fluorescence microscopy was used to verify the attachment of the biotin ligand to the surface of the PGA suture after a complexation with fluorescein-conjugated streptavidin. The strategy can be generalized to surface modifications of other biodegradable aliphatic polyesters, which would improve the properties of the polymers in biomedical applications such as active targeting of drugs based on ligand-attached, polymeric drug delivery systems.

Biodegradation, Environmental↗
PubMed2003

Neuraminidase inhibitors from Reynoutria elliptica.

In the course of screening neuraminidase inhibitors from herbal medicines, Reynoutria elliptica exhibited high inhibitory activity. Four active compounds were isolated from the ethyl acetate soluble fraction by consecutive purification using sillica gel, Sephadex LH-20 chromatography, and recrystallization. The chemical structures of these compounds were identified as 1,3,8-trihydroxy-6-methylanthraquinone (emodin) 1,8-dihydroxy-3-methoxy-6-methylanthraquinone (emodin 3-methyl ether; physcion), 1,3,8-trihydroxy-6-hydoxymethylanthraquinone (omega-hydroxyemodin), and 3,5,4'-trihydroxystilbene (trans-resvertrol) by spectral data including MS, 1H-, and 13C-NMR. The IC50 values of emodin, emodin 3-methyl ether, omega-hydroxyemodin, and trans-resvertrol were 2.81, 74.07, 10.49, and 8.77 microM, respectively. They did not inhibit other glycosidase such as glucosidase, mannosidase, and galactosidase, indicating that they were relatively specific inhibitors of neuraminidase.

Drugs, Chinese Herbal↗
PubMed2003

Neurologic complications of human immunodeficiency virus-type 1 infection.

A wide variety of neurologic complications associated with human immunodeficiency virus-type 1 (HIV-1) infection result from HIV-1 itself or secondarily related to immunosuppression. In Korea, the number of HIV-1 seropositive populations is increasing, but little has been known about the neurologic complications of HIV-1 infection. To investigate the neurologic complications in HIV-1 infected Korean patients, we performed a cross-sectional study in consecutive admissions to the Seoul National University Hospital between March 1998 and June 1999. Thirty-four HIV-1 seropositive patients were included. As a result, a total of 26 HIV-1 related neurologic complications were identified from 17 patients. Among them, 10 patients showed cognitive/motor abnormalities: 3 HIV-1-associated dementia and 7 possible HIV-1-associated minor cognitive/motor disorder. Neuromuscular complications were found in 10 patients: 9 distal symmetric polyneuropathy, and 1 possible chronic inflammatory demyelinating polyradiculoneuropathy. In 3 patients with focal brain lesions, 2 were presumptively diagnosed as having primary CNS lymphoma, and 1 as having progressive multifocal leukoencephalopathy in the posterior fossa, based on history, clinical findings, serology, radiological appearances, and response to empirical therapy. Other complications included cryptococcal meningitis and only soft neurologic signs without any neurologic disease. Most of these complications (88%) occurred in the advanced stage of infection.

Adult↗
PubMed2002

A novel missense mutation (I344K) in the SPG4gene in a Korean family with autosomal-dominant hereditary spastic paraplegia.

Hereditary spastic paraplegia (HSP) is a group of clinically and genetically heterogeneous neurodegenerative disorders characterized by slowly progressive spasticity and weakness of the lower extremities. Among eight loci linked with autosomal-dominant (AD)-HSP, the SPG4 locus on chromosome 2p22 accounts for about 40% of all patients. Recently, mutations in a new member of the AAA protein family, called spastin, have been identified as responsible for SPG4-linked AD-HSP. Here, we describe a novel missense mutation (c.1031T>A; I344K) in exon 7 of the SPG4 gene identified in a Korean family with typical clinical features of pure AD-HSP. The mutation affects the third amino acid of the highly conserved AAA cassette domain, which is the most fore part of the domain altered by a missense mutation reported so far. Clinical presentations of affected individuals carrying the I344K mutation were not different from those of pure AD-HSP with SPG4 mutations reported previously. However, it is noteworthy that neither urinary dysfunction nor involvement of upper extremities was noticed in this family. To our knowledge, this is the first report of genetically confirmed AD-HSP in Korea.

Adenosine Triphosphatases↗