PubMed Health⌕ Search

Biomedical subjects

S H Hwang

Publications and source records attributed to S H Hwang.

At least 19 recordsLinked to original sources
PubMed2004

Enhanced secretion of Bacillus stearothermophilus L1 lipase in Saccharomyces cerevisiae by translational fusion to cellulose-binding domain.

The secretion of Bacillus stearothermophilus L1 lipase in Saccharomyces cerevisiae was investigated by employing a fusion partner, a cellulose-binding domain (CBD) from Trichoderma harzianum endoglucanase II (THEG). The CBD was connected to the N-terminal of L1 lipase through an endogenous linker peptide from THEG. The expression cassette for the fusion protein in S. cerevisiae was constructed using the alpha-amylase signal peptide and the galactose-inducible GAL10 promoter. Secretion of CBD-linker-L1 lipase by this fusion construct was dramatically 7-fold enhanced, compared with that of the mature L1 lipase without CBD-fusion. The fusion protein was secreted into the culture medium, reaching levels of approximately 1.3 g/l in high-cell-density fed-batch cultures. Insertion of a KEX2 cleavage site into the junction between CBD-linker and L1 lipase resulted in the same level of enhanced secretion, indicating that the CBD-linker fusion probably plays a critical role in secretion from endoplasmic reticulum to Golgi apparatus. Therefore, the CBD from THEG can be used both as an affinity tag and as a secretion enhancer for the secretory production of heterologous proteins in S. cerevisiae, since in vivo breakage at the linker was almost negligible.

Amino Acid Sequence↗
PubMed2004

Discrepancy of interleukin-6 levels between end-stage renal disease patients and patients with acute-phase response with increased lipoprotein(a) concentrations.

Though the concentration of serum lipoprotein(a) [Lp(a)] is mostly determined by genetic factors, secondary factors such as acute-phase response (APR) and end-stage renal disease (ESRD) also contribute to its increase. Lp(a) is known to be one of the acute-phase reactants and interleukin-6 (IL-6) is the key cytokine in the hepatic synthesis of acute-phase proteins. The serum concentrations of Lp(a) and IL-6 were measured in patients with APR and in patients with ESRD to investigate the relationship between Lp(a) and IL-6. A total of 180 patients were selected for the study: 60 patients were normal controls, 60 were patients with renal disease who had been on hemodialysis for more than 6 months [C-reactive protein (CRP)<4.0 mg/L], and 60 were APR patients who had a erythrocyte sedimentation rate (ESR) of over 50 mm/h. The three groups were age- and sex matched. The serum concentrations of Lp(a) and IL-6 were measured by ELISA. The serum concentrations of Lp(a) [median (interquartile range)] in normal controls, ESRD patients, and APR patients were 0.222 (0.103-0.364) g/L, 0.511 (0.308-0.755) g/L, and 0.546 (0.234-0.747) g/L, respectively; those of IL-6 were 1.0 (0.7-1.3) pg/mL, 2.1 (1.4-3.3) pg/mL, and 26.2 (15.2-35.6) pg/mL. The concentration of IL-6, which increases Lp(a) synthesis, was much lower in ESRD patients than in APR patients (p<0.001). However, there were no significant differences in Lp(a) concentration between the two groups (p=0.88). In APR patients, the increase in Lp(a) synthesis seems to play a significant role in the increase in blood Lp(a), but there might be different mechanisms that regulate the increment of serum Lp(a) concentrations in ESRD patients other than synthesis of Lp(a).

Acute-Phase Reaction↗
PubMed2001

4d Electronic structure analysis of ruthenium in the perovskite oxides by Ru K- and L-edge XAS.

The 4d electronic structure of ruthenium in the perovskite oxides, La2MRuIVO6 (M = Zn, Mg, and Li) and Ba2YRuVO6, has been investigated by the Ru K-and L-edge XANES and EXAFS analyses. Such X-ray absorption spectroscopic results clarify that the RuIV (d4) and RuV (d3) ions are stabilized in nearly regular Oh site. Comparing the Ru L-edge XANES spectra of perovskites containing isovalent ruthenium, it has been found that the t2g state is mainly influenced by A site cation, whereas the eg is mainly affected by neighboring B site cation. The experimental EXAFS spectra in the range of R < or = approximately 4.5 A are well reproduced by ab-initio calculation based on crystallographic data, which supports the long-range structure presented by Rietveld refinement.

Journal Article↗
PubMed2001

Effects of ADP on different inhibitory properties of brain glutamate dehydrogenase isoproteins by perphenazine.

Incubation of glutamate dehydrogenase isoproteins (GDH I and GDH II) from bovine brains with perphenazine resulted in a time-dependent loss of enzyme activity. 2-Oxoglutarate and NADH, separately or together, gave partial but not complete protection against the inhibition. Although there were no detectable differences between GDH I and GDH II in inhibition by perphenazine in the absence of ADP, the sensitivities to the inhibition by the drug were significantly distinct for the two isoproteins in the presence of ADP. Low concentrations of ADP (0.05-0.20 mM) did not interfere with the inhibition of GDH I and GDH II by perphenazine. However, in the presence of high concentrations of ADP (0.5-1.0 mM), inhibitory effects of perphenazine on GDH isoproteins were significantly diminished as determined by enzyme kinetics and quantitative affinity chromatography on perphenazine-Sepharose. GDH I was more sensitively reacted with ADP than GDH II on the inhibition by perphenazine. Since physiological ADP levels can vary from 0.05 to > 1.0 mM depending on the rate of oxidative phosphorylation, our results suggest a possibility that two types of GDHs are differently regulated by the antipsychotic actions of perphenazine depending on the physiological concentrations of ADP. GTP and L-leucine, other well-known allosteric regulators, did not affect the inhibitory actions of perphenazine on bovine brain GDH isoproteins.

Adenosine Diphosphate↗
PubMed2001

Liver-targeted gene transfer into a human hepatoblastoma cell line and in vivo by sterylglucoside-containing cationic liposomes.

We investigated the transfection efficiency of beta-sitosterol beta-D-glucoside (Sit-G)-containing liposome/DNA complex (Sit-G-liposome/DNA complex) for liver targeting. The Sit-G-liposome/DNA complex was composed of Tfx-20 reagent (Tfx), ie synthetic cationic lipid [N,N,N',N'-tetramethyl-N,N'-bis(2-hydroxyethyl)-2,3-di(oleoyloxy)-1,4-butanediammonium iodide] with L-dioleoylphosphatidylethanolamine (DOPE), 3 beta[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol (DC-Chol) and Sit-G with plasmid DNA. The in vitro studies were performed in HepG2 cells in serum-containing medium and the in vivo studies were carried out in the mice following intravenous injection. The Sit-G-liposome produced a Sit-G-liposome/DNA complex of relatively small size (100--250 nm). Transfection efficiency of the luciferase marker gene by Sit-G-liposome/DNA complex was increased in the presence of 10% serum in vitro, and was selectively high in the mouse liver reaching expression values up to an average of 14.9 pg luciferase/mg tissue protein, compared with Tfx/DNA complex, which showed approximately three-fold higher gene expression than Sit-G-liposome/DNA complex in vitro. High in vitro transfection efficiency by Sit-G-liposome/DNA complex seemed to be possible even with large lipid precipitates, whereas high in vivo activity seemed to be related to small and dispersed complexes. The interaction of liposome/DNA complexes with serum may be a key point to predict the in vivo efficiency of a liposome vector.

Animals↗
PubMed2001

Head tilt suppression test as a differential diagnostic tool in vertiginous patients.

The head tilt suppression test has been known to be a diagnostic tool to distinguish between centrally originating dizziness and peripheral vertigo, as the latter enhances the natural spontaneous firing rate of the velocity storage system and decreases the time constant; however, the otolith organ is now considered to be a cause of head tilting effect. Therefore we questioned whether the head tilt suppression test is still worth differential diagnostic tool. We measured the time constant and initial eye velocity of pre- and post-rotatory nystagmus in a velocity step test in nine healthy adults. The time constant was significantly affected by head tilting (p = 0.001), pre- and post-rotatory nystagmus (p = 0.020) and the compounding interaction between them (p < 0.000). The initial eye velocity was also significantly affected by pre- and post-rotatory nystagmus (p = 0.016) and the compounding interaction (p < 0.000), but not by head tilting (Wilks' Lambda = 0.054). The head tilt suppression test is a useful method for the differential diagnosis of vertiginous patients. It is affected by pre- and post-rotatory nystagmus and their interaction, however, other central parameters in vestibular function testing should also be considered in order to obtain an exact differential diagnosis.

Adult↗
PubMed2000

An efficient cell-free protein synthesis system using periplasmic phosphatase-removed S30 extract.

An efficient cell-free translation system was developed by removal of phosphatase localized in the periplasmic space, which hampers the translation reaction by hydrolyzing ATP. S30 extract was prepared from the spheroplast of Escherichia coli, and as much as 40% of ATP-hydrolysis activity of phosphatases could be easily removed by the spheroplast formation. The reaction period of translation using phosphatase-removed S30 extract could be prolonged and protein synthesis was enhanced by more than 30%.

Cell-Free System↗
PubMed2000

Cloning and sequence analysis of cDNA for diuretic hormone receptor from the Bombyx mori.

The insect diuretic hormone (DH) binds to their receptor in malpighian tubules, and stimulates water secretion and cAMP synthesis. Complementary DNA encoding a diuretic hormone receptor was cloned from the malpighian tubules of Bombyx mori. The cloned cDNA encodes a protein consisting of 391 amino acid residues with the seven transmembrane domains. The receptor protein is homologous with that of other insects, and is structurally related to G-protein coupled receptors such as corticotropin relating factor (CRF), secretin, and vasoactive intestinal peptide.

Amino Acid Sequence↗
PubMed2000

Repression of hspA2 messenger RNA in human testes with abnormal spermatogenesis.

OBJECTIVE: To evaluate the messenger RNA (mRNA) expression of hspA2 in testes of infertile men with azoospermia. DESIGN: Prospective study. SETTING: Center for Reproduction and Genetics, Pundang Je-Saeng General Hospital, Dae-Jin Medical Center, Korea. PATIENT(S): Azoospermic patients (n = 15) undergoing testicular biopsy for pathologic evaluation were selected. INTERVENTION(S): After pathologic evaluation, testicular biopsy specimens were subdivided into three groups: group 1, normal spermatogenesis (n = 5); group 2, spermatocyte arrest (n = 5); and group 3, Sertoli cell-only syndrome (n = 5). The levels of hspA2 mRNA expression were compared in testes of group 1, group 2, and group 3 with the use of a competitive reverse transcription polymerase chain reaction (RT-PCR) technique. MAIN OUTCOME MEASURE(S): Comparison of hspA2 mRNA levels in testes. RESULT(S): On competitive RT-PCR analyses for hspA2 mRNA, significant hspA2 expression was observed in group 1, whereas a very low level of hspA2 was expressed in groups 2 and 3. CONCLUSION(S): This study demonstrates that hspA2 gene expression is down-regulated in human testes with abnormal spermatogenesis, which in turn suggests that the hspA2 gene might play a specific role during meiosis in human testes.

Cell Cycle↗
PubMed2000

Cloning and characterization of a Bacillus thuringiensis serovar higo gene encoding a novel class of the delta-endotoxin protein, Cry27A, specifically active on the Anopheles mosquito.

A novel gene encoding a 98-kDa mosquitocidal delta-endotoxin protein, designated Cry27A, was cloned from a Bacillus thuringiensis serovar higo strain. The Cry27A protein contained the five sequence blocks of amino acids commonly conserved in most B. thuringiensis Cry proteins. Relatively high homologies, ranging from 43.0% to 84.4%, existed between the Cry27A protein and several established classes of mosquitocidal Cry proteins (Cry4A, Cry10A, Cry19A, Cry19B, and Cry20A) in the sequence of 51 N-terminal amino acids. The complete sequence of this protein, however, showed low levels (<40%) of amino acid identity to those of the known Cry proteins. Although the expression level of the cry27A gene was low in the transformants under the control of its own promoter, the use of the cyt1A promoter resulted in high-level expression of the gene, leading to the formation of inclusions. The expressed Cry27A protein showed larvicidal activity highly specific for Anopheles stephensi, but lacked the toxicity against Culex pipiens molestus and Aedes aegypti. The results suggest that the Cry27A protein is responsible for the Anopheles-preferential toxicity of the B. thuringiensis serovar higo strain.

Amino Acid Sequence↗
PubMed2000

Synthesis and biological evaluation of 1-(4-[18F]fluorobenzyl)-4-[(5,6-dimethoxy-1-oxoindan-2-yl)methyl]piperidine for in vivo studies of acetylcholinesterase.

We synthesized and evaluated 1-(4-fluorobenzyl)-4-[(5,6-dimethoxy-1-oxoindan-2-yl)methyl]piperidine (4-FDP), which is an analog of donepezil. The 4-[(18)F]FDP was prepared by reductive alkylation of debenzylated donepezil with 4-[(18)F]fluorobenzaldehyde in high radiochemical yield (decay-corrected, 40-52%) and with high effective specific activity (30-38 GBq/micromol). Tissue distribution studies in mice demonstrated nonspecific distribution of the 4-[(18)F]FDP in brain regions, suggesting that this radioligand may not be a suitable agent for in vivo studies of acetylcholinesterase (AChE), despite its potent in vitro biological activity.

Acetylcholinesterase↗
PubMed2000

Cleft lip nose correction with onlay calvarial bone graft and suture suspension in Oriental patients.

To correct the secondary cleft lip nose deformity in Oriental patients, many alar cartilage mobilization and suspension techniques have been developed. However, these techniques have critical limitations. One of the limitations is the suspension vector, and another is suspension power. The suspension vector is from inferior to superior and from the deformed alar cartilage to the normal alar cartilage. Thus, the vector is not suitable for normal nasal tip projection. The suspension power is not satisfactory because Oriental people have underdeveloped, thin alar cartilages and thick skin. So, the suspended, deformed alar cartilage may relapse and pull the normal alar cartilage to the deformed side. To overcome these limitations, the authors use the cantilever calvarial bone graft for tip projection; it also serves as a strong, rigid framework for cartilage and soft-tissue suspension. Using these techniques, the authors can create normal nasal tip projection and a normal looking nasal aperture.

Abnormalities, Multiple↗
PubMed2000

High entrapment of insulin and bovine serum albumin into neutral and positively-charged liposomes by the remote loading method.

Remote loading of insulin and bovine serum albumin (BSA) into neutral or positively-charged liposomes by incubation under a transmembrane pH gradient or non-pH gradient was investigated. Trapping efficiencies in several incubation conditions were compared with those of the conventional reverse-phase evaporation vesicle method (c-REV method). For neutral liposomes, insulin could not be effectively loaded into the liposomes by incubation, regardless of the incubation conditions. The trapping efficiency of insulin into positively-charged liposomes was higher than that of neutral liposomes, especially by the pH-gradient method. Insulin could be loaded into positively-charged liposomes about twofold more efficiently than by the pH-gradient method, compared with the c-REV method. Insulin distributed more on the surface of liposomes by the pH-gradient method than by the c-REV method. BSA showed significantly higher affinity to positively-charged liposomes than to neutral ones by various methods. However, the transmembrane pH-gradient method did not increase BSA loading into liposomes, compared with the c-REV and the non-pH-gradient methods. Our results suggest that the pH-gradient method, combining electrostatic interactions, may be useful for preparation of liposomal insulin and that the high hydrophobicity of BSA may not increase the remote loading of BSA into liposomes by the pH-gradient method.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

Electron spin resonance studies of dipalmitoylphosphatidylcholine liposomes containing soybean-derived sterylglucoside.

The effects of soybean-derived sterylglucoside (SG) on the fluidity of liposomal membrane composed of dipalmitoylphosphatidylcholine (DPPC) were investigated compared with those of soybean-derived sterol (SS) and cholesterol (Ch) using an electron spin resonance spectrometer. Three kinds of liposomes were prepared in the molar ratio of DPPC/X=7/4, where X is SS, Ch or SG. The fluidity close to the polar head groups increased with an increase of temperature in the DPPC membrane containing SS, Ch and SG in the range 35 to 45 degrees C. Those near the hydrophobic end changed with an increase in temperature in liposomes containing SS, Ch and SG, which had a fluidizing effect on the DPPC membrane below the transition temperature (Tm, 41.9 degrees C) and a condensing effect over the Tm. The fluidizing effects of these compounds around 37 degrees C near the polar head group and the hydrophobic end increased in the following order: Ch < SG < or = SS and SS < Ch < SG, respectively. SG increased the fluidity of liposomal membrane dramatically above the Tm (35.4 degrees C). These results suggest that the high fluidity close to the hydrophobic end of the liposomal membranes around 37 degrees C, the decrease of Tm, and the sigmoidal nature of fluidity vs. temperature are important factors in the effectiveness of liposomes containing SG as a carrier of drugs.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

In vitro activities of quinupristin/dalfopristin and eight other antimicrobial agents against 360 clinical isolates from Korea.

The emergence of multi-drug resistant gram-positive cocci such as methicillin-resistant (MR) staphylococci, vancomycin-resistant (VR) enterococci, and vancomycin-intermediate resistant S. aureus (VISA) has given new urgency to the development of new antimicrobial agents. One of these is quinupristin/dalfopristin (Q/D). We decided to determine the susceptibility of gram-positive cocci isolated at two university hospitals in Seoul to Q/D and compare the results with eight other antimicrobial agents. We investigated 120 isolates of S. aureus including 49 MRSAs and one VISA, 120 isolates of coagulase negative staphylococci (CNS), 64 E. faecalis and 56 E. faecium, including seven strains of VR E. faecium. Minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) for several antimicrobials, including vancomycin and Q/D, were determined by broth microdilution. All S. aureus including VISA were susceptible to Q/D. Q/D MIC90 for both methicillin-susceptible S. aureus (MSSA) and MRSA was 0.25 g/mL. 49 (87.5%) of 56 E. faecium including six of seven VR E. faecium were susceptible to Q/D. E. faecalis were not susceptible to Q/D (only 1.5% susceptible), but were inhibited by ampicillin (94% susceptible) or vancomycin (95%). CNS was susceptible to Q/D (96% susceptible) and vancomycin (100% susceptible). One of 38 staphylococci and two of 17 E. faecium were tolerant to Q/D. In conclusion, Q/D showed excellent activity against all species of gram-positive cocci including MRSA, VISA, and VR E. faecium except E. faecalis, and may provide a valuable option for the treatment of infections caused by these emerging nosocomial pathogens of gram-positive cocci.

Anti-Bacterial Agents↗