Biomedical subjects

B H Lee

Publications and source records attributed to B H Lee.

At least 37 records · Page 2Linked to original sources

PubMed2003

Identification of an encystation-specific transcription factor, Myb protein in Giardia lamblia.

The life cycle of Giardia lamblia contains two differentiation processes, encystation and excystation. We performed an experiment to identify the genes induced during encystation using the differential display reverse transcriptase-polymerase chain reaction. Three of twelve isolated cDNA clones that showed increased transcription during encystation were identified to be of the myb2, which encodes a well-known transcriptional factor involved in cellular development and differentiation. The amino acid sequences of the Myb2 protein deduced from the isolated gene revealed that this Myb2 has a DNA binding domain comprising two imperfect repeats at its carboxyl-terminus. The nuclear localization of Myb2 protein during encystation was observed in vivo by expressing a Myb2-GFP fusion protein. In a random site selection experiment, the oligonucleotides bound by rMyb2 contained a conserved sequence of GTTT(G/T)(G/T). Two promoters of the encystation-induced genes, myb2, and cwp1, were also found to bind to rMyb2, whereas gap1, one of the constitutive genes did not.

Animals↗

PubMed2003

Wax moth, Galleria mellonella, high density lipophorin receptor: alternative splicing, tissue-specific expression, and developmental regulation.

A lipophorin (Lp) receptor cDNA from the fat body of Galleria mellonella (Lepidoptera) was cloned and sequenced. This is the first result in this order, Lepidoptera. It showed the pattern of the VLDL receptor belonging to the LDL receptor family. Sequence homology with other Lp receptors in insects, Locusta migratoria and Aedes aegypti, was 70 and 61%, respectively and each domain was highly conserved. Polyclonal anti-Lp receptor antibody prepared against expressed Lp receptor fragment between ligand binding domain and EGF-precursor homology domain (R305-D549 of amino acid residues) specifically detected the Lp receptor. Through immuno-blotting, the Lp receptor of larval fat body has an approximate molecular mass of about 97 and 110 kDa under non-reducing and reducing conditions, respectively. This result was in agreement with that of the ligand-blotting. The variant Lp receptors were expressed in the fat body of G. mellonella; one is an Lp receptor which lacks 84 bp of O-linked sugar domain and the other is a full length form of the Lp receptor. Both forms were detected by the polyclonal anti-Lp receptor antibody. The Lp receptor from the fat body of G. mellonella was differently expressed depending on the tissue and the developmental stage with specific abundance in prepupal stage. A steroid hormone, 20-hydroxyecdysone (20-HE) plays a crucial role in insect development. With regards to this conception, day 1-2 last instar larvae were treated with 20-HE and drastic induction of the Lp receptor was observed 48 h after treatment. It was also observed that cholesterol caused an induction of the Lp receptor.

Amino Acid Sequence↗

PubMed2003

Hepatoprotective and free radical scavenging effects of Nelumbo nucifera.

Ethanol extracts from Nelumbo nucifera (ENN) seeds were studied for possible antioxidative and hepatoprotective effects. Antioxidative effects were measured spectrophotometrically by reduction of 2,2'-Diphenyl-1-picrylhydrazyl (DPPH) radicals. Hepatoprotective effects were tested using carbon tetrachloride (CCl4) and aflatoxin B1 (AFB1)-induced hepatocyte toxicity models. ENN showed potent free radical scavenging effects with a median inhibition concentration of 6.49 microg/ml. Treatment of hepatocytes with ENN inhibited both the production of serum enzymes and cytotoxicity by CCl4. The genotoxic and cytotoxic effects of AFB1 were also inhibited by ENN in dose-dependent manners. These hepatoprotective effects of ENN against CCl4 and AFB1 might result from its potent antioxidative properties.

Aflatoxin B1↗

PubMed2002

Influence of final search direction on tactile line bisection in normal subjects.

BACKGROUND: Many variables influence the tactile bisection performance of normal subjects. Of these, studies that investigated the starting point effect have reported inconsistent results. OBJECTIVE: To determine if the final search direction rather than the initial search direction (starting point) may have an effect on tactile bisection performance, especially when subjects are making multiple searches. METHODS: The authors divided the experiment into single- and multiple-search tasks. Thirty-two blindfolded normal subjects were asked to indicate the midpoint of a rod after a one-way search (single-search task) or after two or more one-way searches (multiple-search task). In each task, the subject started on either end of the horizontally placed rods. The same procedure was also conducted with rods oriented vertically or radially. Therefore, there were six conditions (two starting points x three orientations). RESULTS: In the single-search task, there was a significant effect of starting point or movement direction in all six conditions, with biases occurring toward the starting point from the true midpoint (this is termed the "overshoot phenomenon"). In the multiple-search task, however, there was no significant effect of the starting point in all six conditions. Rather, biases depended on the final movement direction in five of the six conditions, occurring toward the starting point of the final search. CONCLUSION: Future research is needed to understand the mechanism of the overshoot phenomenon in tactile bisection by normal subjects and how the overshoot phenomenon influences patients with neglect.

Adult↗

PubMed2002

Purification and characterization of a recombinant beta-galactosidase with transgalactosylation activity from Bifidobacterium infantis HL96.

A beta-galactosidase isoenzyme, beta-Gall, from Bifidobacterium infantis HL96, was expressed in Escherichia coli and purified to homogeneity. The molecular mass of the beta-Gall subunit was estimated to be 115 kDa by SDS-PAGE. The enzyme appeared to be a tetramer, with a molecular weight of about 470 kDa by native PAGE. The optimum temperature and pH for o-nitrophenyl-beta-D-galactopyranoside (ONPG) and lactose were 60 degrees C, pH 7.5, and 50 degrees C, pH 7.5, respectively. The enzyme was stable over a pH range of 5.0-8.5, and remained active for more than 80 min at pH 7.0, 50 degrees C. The enzyme activity was significantly increased by reducing agents. Maximum activity required the presence of both Na+ and K+, at a concentration of 10 mM. The enzyme was strongly inhibited by p-chloromercuribenzoic acid, divalent metal cations, and Cr3+, and to a lesser extent by EDTA and urea. The hydrolytic activity using lactose as a substrate was significantly inhibited by galactose. The Km, and Vmax values for ONPG and lactose were 2.6 mM, 262 U/mg, and 73.8 mM, 1.28 U/mg, respectively. beta-Gall possesses strong transgalactosylation activity. The production rate of galactooligosaccharides from 20% lactose at 30 and 60 degrees C was 120 mg/ml, and this rate increased to 190 mg/ml when 30% lactose was used.

Bifidobacterium↗

PubMed2002

Effects of luteolin on the inhibition of proliferation and induction of apoptosis in human myeloid leukaemia cells.

Luteolin, a flavonoid isolated from the fruit of Vitex rotundifolia, has been examined with regard to the inhibition of proliferation and induction of apoptosis in human myeloid leukaemia HL-60 cells. The concentration required for 50% inhibition of the growth after 96 h was 15 +/- 1.1 microM. The mode of cell death induced by luteolin was found to be apoptosis, as judged by the morphologic alteration of the cells and by the detection of DNA fragmentation using agarose gel electrophoresis. The degree of apoptosis was quantified by a sandwich enzyme immunoassay and flow cytometric analysis. These results suggest that luteolin may be used as potential chemopreventive and chemotherapeutic agents.

Antineoplastic Agents, Phytogenic↗

PubMed2002

A simplified cardiopulmonary bypass technique for animal experiments on implantable ventricular assist devices.

We have developed and report on a simplified cardiopulmonary bypass technique for experiments on implantable ventricular assist devices in calves. We used an electromechanical implantable ventricular assist device with a double cylindrical cam in three calves. Cannulas for the ventricular assist system were designed to be inserted between the left atrium and the descending aorta. We used the outflow cannula of the ventricular assist device, anastomosed to the descending aorta, as a temporary arterial return route for the cardiopulmonary bypass. A cannula for venous drainage was iserted into the right ventricle through the pulmonary artery. There were no problems related to the procedure and the cardiopulmonary bypass was succesful. In conclusion, this simplified cardiopulmonary bypass technique without neck incision in calves, as used in developmental work involving implantable ventricular assist devices, can be reliably performed.

Animals↗

PubMed2001

N-nitrosocarbofuran, but not carbofuran, induces apoptosis and cell cycle arrest in CHL cells.

Carbofuran (CF) is one of the most widely used carbamate pesticides in the world applied for insect and nematode control. Due to its widespread use in agriculture and households, contamination of food, water, and air has become serious, and consequently adverse health effects are inevitable in humans, animals, wildlife and fish. It has been reported that CF alone or in combination with other carbamate insecticides influences the level of reproductive and metabolic hormones such as thyroxine and corticosterone, and results in impairment of endocrine, immune and behavioral functions. In this study, we evaluated the effects of CF and its metabolite, the N-nitroso derivative N-nitrosocarbofuran (NOCF), on genotoxicity, cell growth, cell cycle and apoptosis of Chinese hamster lung fibroblast (CHL) cells. NOCF, but not CF, induced genotoxicity determined by Ames test. NOCF inhibited the growth of Chinese hamster lung fibroblast (CHL) cells with an IC(50) of 12.8 microM. NOCF induced apoptosis of CHL cells, which was demonstrated by morphological changes, DNA fragmentation and flow cytometric analysis. Treatment of CHL cells with NOCF induced significant G(2)/M cell cycle arrest. Caspase-3, an executioner of apoptosis was also activated by the treatment of CHL cells with NOCF. These results suggest that NOCF, that is an important metabolite of CF, leads to the induction of cell cycle arrest and apoptosis in CHL cells.

Animals↗

PubMed2001

A novel anti-ischemic ATP-sensitive potassium channel (K(ATP)) opener without vasorelaxation: N-(6-aminobenzopyranyl)-N'-benzyl-N' '-cyanoguanidine analogue.

This paper describes the design, synthesis, and biological evaluation of a novel anti-ischemic compound, (2S,3S,4R)-N-(6-amino-3,4-dihydro-2-dimethoxymethyl-3-hydroxy-2-methyl-2H-benzopyranyl)-N'-benzyl-N"-cyanoguanidine (33), and the structure-activity relationships leading to the discovery of this compound. Compound 33 significantly reduced the myocardial infarct zone to area at risk (IZ/AAR) in the ischemic myocardium rat model with high cardioselectivity. Since the cardioprotective effect of compound 33 is reversed by ATP-sensitive potassium channel (K(ATP)) blockers, its anti-ischemic effect appears to be at least mediated by K(ATP) opening. In addition, compound 33 shows good protective activity on neuronal cells against oxidative stress, and therefore it is suggested that compound 33 may have therapeutic potential both in cardio- and in neuroprotection.

Adenosine Triphosphate↗

PubMed2001

AtHKT1 is a salt tolerance determinant that controls Na(+) entry into plant roots.

Two Arabidopsis thaliana extragenic mutations that suppress NaCl hypersensitivity of the sos3-1 mutant were identified in a screen of a T-DNA insertion population in the genetic background of Col-0 gl1 sos3-1. Analysis of the genome sequence in the region flanking the T-DNA left border indicated that sos3-1 hkt1-1 and sos3-1 hkt1-2 plants have allelic mutations in AtHKT1. AtHKT1 mRNA is more abundant in roots than shoots of wild-type plants but is not detected in plants of either mutant, indicating that this gene is inactivated by the mutations. hkt1-1 and hkt1-2 mutations can suppress to an equivalent extent the Na(+) sensitivity of sos3-1 seedlings and reduce the intracellular accumulation of this cytotoxic ion. Moreover, sos3-1 hkt1-1 and sos3-1 hkt1-2 seedlings are able to maintain [K(+)](int) in medium supplemented with NaCl and exhibit a substantially higher intracellular ratio of K(+)/Na(+) than the sos3-1 mutant. Furthermore, the hkt1 mutations abrogate the growth inhibition of the sos3-1 mutant that is caused by K(+) deficiency on culture medium with low Ca(2+) (0.15 mM) and <200 microM K(+). Interestingly, the capacity of hkt1 mutations to suppress the Na(+) hypersensitivity of the sos3-1 mutant is reduced substantially when seedlings are grown in medium with low Ca(2+) (0.15 mM). These results indicate that AtHKT1 is a salt tolerance determinant that controls Na(+) entry and high affinity K(+) uptake. The hkt1 mutations have revealed the existence of another Na(+) influx system(s) whose activity is reduced by high [Ca(2+)](ext).

Alleles↗

PubMed2001

An Ochrobactrum anthropi gene conferring paraquat resistance to the heterologous host Escherichia coli.

A new gene, pqrA, conferring paraquat resistance to the heterologous host Escherichia coli, from a chromosomal DNA library of Ochrobactrum anthropi JW2, was cloned and analyzed. Cells of E. coli transformed with a plasmid carrying the pqrA gene showed elevated resistance to paraquat, but not to hydrogen peroxide. The predicted amino acid sequence of the PqrA polypeptide showed 71% identity with mll7495 hypothetical membrane protein in Mesorhizobium loti, 49% identity with PA2269 protein in Pseudomonas aeruginosa, and significant identity with other previously reported drug transport proteins. The hydropathy pattern of the PqrA polypeptide showed a significant homology to those of 12-transmembrane-segment (TMS) family export proteins. Immunoblot analysis demonstrated that the PqrA protein found in the membrane protein fraction of O. anthropi JW2 has a molecular mass of 42 kDa. These results suggest that the PqrA protein is a membrane protein that plays an important role in protecting cells against paraquat toxicity.

Amino Acid Sequence↗

PubMed2001

Mitochondrial NADH-cytochrome b(5) reductase plays a crucial role in the reduction of D-erythroascorbyl free radical in Saccharomyces cerevisiae.

The relevance of NADH-cytochrome b(5) reductase to the NADH-dependent reduction of D-erythroascorbyl free radical was investigated in Saccharomyces cerevisiae. MCR1, which is known to encode NADH-cytochrome b(5) reductase in S. cerevisiae, was disrupted by the insertion of URA3 gene into the gene of MCR1. In the mcr1 disruptant cells, the activity of NADH-D-erythroascorbyl free radical reductase almost disappeared and the intracellular level of D-erythroascorbic acid was about 11% of that of the congenic wild-type strain. In the transformant cells carrying MCR1 in multicopy plasmid, the intracellular level of D-erythroascorbic acid and the activity of NADH-D-erythroascorbyl free radical reductase increased up to 1.7-fold and 2.1-fold, respectively. Therefore, it indicated that the MCR1 product, mitochondrial NADH-cytochrome b(5) reductase, plays a key role in the NADH-dependent reduction of D-erythroascorbyl free radical in S. cerevisiae. On the other hand, the mcr1 disruptant cells were hypersensitive to hydrogen peroxide and menadione, and overexpression of MCR1 made the cells more resistant against oxidative stress. These results suggested that the mitochondrial NADH-cytochrome b(5) reductase functions as NADH-D-erythroascorbyl free radical reductase and plays an important role in the response to oxidative damage in S. cerevisiae.

Ascorbic Acid↗

PubMed2001

In vivo antitumor effect of herpes simplex virus thymidine kinase gene therapy in rat hepatocellular carcinoma: feasibility of adenovirus-mediated intra-arterial gene delivery.

Transfer of the herpes simplex virus-thymidine kinase gene, followed by the administration of ganciclovir (HSV-tk/GCV), has been a major approach for cancer gene therapy. We investigated the antitumor effect of the HSV-tk/GCV strategy with the rat orthotopic hepatocellular carcinoma (HCC) model and the tumor-selective gene delivery by an adenovirus-mediated gene transfer through the hepatic artery. The complete antitumor effect was demonstrated, after the treatment with GCV in rat HCC established by the implantation of HSV-tk transferred rat HCC cells. The in vivo bystander effect was also observed. The marked infiltration of CD4+ and CD8+ T lymphocytes, macrophages and NK cells were found in the tumor area. After the injection of adenovirus carrying the LacZ gene into the hepatic artery, the selective expression of transgene in the tumor cell was achieved. These findings indicate that the HSV-tk/GCV strategy, using an adenoviral vector, could be a promising avenue for the treatment of hepatocellular carcinoma.

Adenoviridae↗

PubMed2001

Molecular characterization of cDNA clones for ADP-glucose pyrophosphorylase from Citrus.

Two cDNA clones encoding ADP-glucose pyrophosphorylases have been isolated from fruit and leaf cDNA libraries of Citrus (Citrus unshiu Mac. cv. Miyagawa) in which one was designated as agpS for the small subunit and the other as agpL for the large subunit. Both cDNAs have uninterrupted open reading frames deriving 57-58 kDa polypeptides. The deduced amino acid sequence of agpS has a unique feature. That is, it lacks a cysteine residue (Cys-12) which is usually conserved in all other dicot enzymes. This is the first report of agpS lacking Cys-12 among dicot small subunits. The expression pattern of both subunits showed a different profile in which leaves synthesized both agpS and agpL more vigorously than those of fruits. During leaf development, the transcripts of agpS and agpL showed a higher expression level at younger stages. During fruit development, the expression level of both subunits was observed to be highest in the mini-green stage, but it decreased in the small green stage and it increased again towards the maturing stage. These results suggest that both subunits may play an important role in the regulation of Citrus fruit and leaf development.

Amino Acid Sequence↗

PubMed2001

Semi-synthesis of 2-deoxo- and 3-epi-paraherquamide A.

2-Deoxo- and 3-epi-paraherquamide A were synthesized from paraherquamide A. 2-Deoxoparaherquamide A has good activity against HC and TC in our jird model comparable to the parent compound, while 3-epi-paraherquamide A showed no activity.

Animals↗

PubMed2001

Identification of two proteins, S14 and UIP1, that interact with UCH37.

By the use of the yeast two-hybrid screen we have identified two proteins that interacted with UCH37: S14, which is a subunit of PA700 and a novel protein, UIP1 (UCH37 interacting protein 1). The interaction of UCH37 with S14 or UIP1 was confirmed by in vitro binding assay and in vivo co-immunoprecipitation analysis. The C-terminal extension of UCH37 is essential for interaction with S14 or UIP1 as shown by the yeast two-hybrid assay and the in vitro binding assay. Furthermore, UIP1 blocked the interaction between UCH37 and S14 in vitro.

Amino Acid Sequence↗

PubMed2001

Fumigant toxicity of volatile natural products from Korean spices and medicinal plants towards the rice weevil, Sitophilus oryzae (L).

The fumigant toxicity of various volatile constituents of essential oils extracted from sixteen Korean spices and medicinal plants towards the rice weevil, Sitophilus oryzae L (Coleoptera: Curculionidae), was determined. The most potent toxicity was found in the essential oil from Mentha arvensis L. var piperascens (LC50 = 45.5 microliters litre-1 air). GC-MS analysis of essential oil from M arvensis showed it to be rich in menthol (63.2%), menthone (13.1%) and limonene (1.5%), followed in abundance by beta-pinene (0.7%), alpha-pinene (0.6%) and linalool (0.2%). Treatment of S oryzae with each of these terpenes showed menthone to be most active (LC50 = 12.7 microliters litre-1 air) followed by linalool (LC50 = 39.2 microliters litre-1 air) and alpha-pinene (LC50 = 54.9 microliters litre-1 air). Studies on inhibition of acetylcholinesterase activity of S oryzae showed menthone to have a nine-fold lower inhibitory effect than menthol, despite menthone being 8.1-fold more toxic than menthol to the rice weevil. Different modes of toxicity of these monoterpenes towards S oryzae are discussed.

Acetylcholinesterase↗

PubMed2001

Rotundifuran, a labdane type diterpene from Vitex rotundifolia, induces apoptosis in human myeloid leukaemia cells.

The inhibitory effect of rotundifuran, a labdane type diterpene isolated from the fruit of Vitex rotundifolia, on the proliferation of human myeloid leukaemia HL-60 cells was examined. The concentration required for 50% inhibition of the growth after 96 h was 22.5 microM. The mode of cell death induced by rotundifuran was found to be apoptosis, which was judged by the morphological alteration of the cells and by the detection of DNA fragmentation using agarose gel electrophoresis. The degree of apoptosis was quantified by a sandwich enzyme immunoassay and flow cytometric analysis. These results suggest that rotundifuran may be used as a potential chemopreventive and chemotherapeutic agent.

Antineoplastic Agents, Phytogenic↗