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Biomedical subjects

S W Kang

Publications and source records attributed to S W Kang.

At least 55 records · Page 3Linked to original sources
PubMed2000

CRAMP analogues having potent antibiotic activity against bacterial, fungal, and tumor cells without hemolytic activity.

CRAMP-18 (GEKLKKIGQKIKNFFQKL) is the antibacterial sequence derived from CRMAP, a member of cathelicidin-derived antimicrobial peptides. To develop the novel antibiotic peptides useful as therapeutic drugs requires strong antibiotic activity against bacterial and fungal cells without hemolytic effect. To this goal, the analogues were designed to increase only net positively charge by Lys-substitution of positions 2, 9, 13, or 16 at the hydrophilic helix face of CRAMP-18 without any change at the hydrophobic helix face. In particular, Lys-substitution (K(2)-CRAMP-18) of position 2 in CRAMP-18 induced the enhanced antibiotic activity without any increase in hemolysis. Thus, this peptide may provide a useful template for the design novel antibiotic peptides for the treatment of infectious diseases. Additional CD spectra studies suggested that the alpha-helical structure of the peptides plays an important role in killing bacterial and fungal cells, but the increase of alpha-helical content is less connected with the enhanced antibiotic activity.

Amino Acid Sequence↗
PubMed2000

Identification of a new type of mammalian peroxiredoxin that forms an intramolecular disulfide as a reaction intermediate.

Peroxidases of the peroxiredoxin (Prx) family contain a Cys residue that is preceded by a conserved sequence in the NH(2)-terminal region. A new type of mammalian Prx, designated PrxV, has now been identified as the result of a data base search with this conserved Cys-containing sequence. The 162-amino acid PrxV shares only approximately 10% sequence identity with previously identified mammalian Prx enzymes and contains Cys residues at positions 73 and 152 in addition to that (Cys(48)) corresponding to the conserved Cys. Analysis of mutant human PrxV proteins in which each of these three Cys residues was individually replaced with serine suggested that the sulfhydryl group of Cys(48) is the site of oxidation by peroxides and that oxidized Cys(48) reacts with the sulfhydryl group of Cys(152) to form an intramolecular disulfide linkage. The oxidized intermediate of PrxV is thus distinct from those of other Prx enzymes, which form either an intermolecular disulfide or a sulfenic acid intermediate. The disulfide formed by PrxV is reduced by thioredoxin but not by glutaredoxin or glutathione. Thus, PrxV mutants lacking Cys(48) or Cys(152) showed no detectable thioredoxin-dependent peroxidase activity, whereas mutation of Cys(73) had no effect on activity. Immunoblot analysis revealed that PrxV is widely expressed in rat tissues and cultured mammalian cells and is localized intracellularly to cytosol, mitochondria, and peroxisomes. The peroxidase function of PrxV in vivo was demonstrated by the observations that transient expression of the wild-type protein, but not that of the Cys(48) mutant, in NIH 3T3 cells inhibited H(2)O(2) accumulation and activation of c-Jun NH(2)-terminal kinase induced by tumor necrosis factor-alpha.

Amino Acid Sequence↗
PubMed2000

Cytoprotective effect of arginine deiminase on taxol-induced apoptosis in DU145 human prostate cancer cells.

We purified and partially sequenced a cytostatic protein from the ASC-17D Sertoli cell-conditioned media (rSCCM) showing a molecular weight of 90 kDa with homodimeric composition. N-terminal amino acid analysis revealed that the protein was homologous to the arginine deiminase (ADI) of Mycoplasma arginini. We found ADI enzyme activity in rSCCM and the abolishment of the growth inhibitory effect by the supplement of L-arginine. Thus, we confirmed that the cytostatic activity in rSCCM was due to the depletion of extracellular L-arginine by ADI. Apparent increase of cell death or DNA fragmentation was not observed in DU145 cells cultured in the presence of ADI. Incubation of DU145 cancer cells with taxol resulted in a marked DNA fragmentation, whereas pretreatment with ADI or cycloheximide protected the cells from taxol-induced apoptosis. Preincubation of the cells with ADI inhibited S35-methionine incorporation into protein synthesis in a dose dependent manner. These data suggest that ADI-induced arginine depletion may inhibit protein synthesis, and result in the protection of apoptotic cell death that requires new protein synthesis.

Amino Acid Sequence↗
PubMed2000

Cloning, sequencing, and expression of porcine interleukin-18 in Escherichia coli.

IL-18 is the new name of a novel cytokine that plays an important role in T(H1) response, primarily by its ability to induce IFN-gamma production in T cells and natural killer cells. The porcine IL-18 gene was isolated using RT-PCR from porcine alveolar macrophages. Sequence analysis of the porcine IL-18 gene has demonstrated an open reading frame of 579 base pairs encoding 192 amino acids precursor protein with a predicted molecular mass of 22 kDa. The porcine IL-18 gene shares 84% and 89% similarity to the human and canine equivalents, respectively, at the nucleotide level. The cloned IL-18 was expressed in Escherichia coli and its expression was confirmed by SDS-PAGE and Western blotting.

Amino Acid Sequence↗
PubMed2000

Antisense oligonucleotide of clusterin mRNA induces apoptotic cell death and prevents adhesion of rat ASC-17D Sertoli cells.

Clusterin has been known to play important roles in cell-cell and/or cell-substratum interactions. Recently we reported the transient expression of clusterin in pancreatic endocrine cells during the early developmental stages and suggested a role in aggregating the endocrine cells for islet formation. In the present study, we have investigated the involvement of clusterin in cell-substratum interaction by the inhibition of clusterin synthesis using antisense oligonucleotide. The expression of clusterin was transiently increased as early as 2-8 h after plating the ASC-17D Sertoli cells to the culture flask, which was the period of cell attachment. In addition, up-regulation of clusterin mRNA was so much greater when the Sertoli cells were plated on the petri dish for the bacterial culture instead of in a animal cell culture flask that therefore, the cells failed to attach to it. These findings suggested that interruption of cell to plate substratum interaction might lead to over-expression of clusterin from Sertoli cells to induce cell to cell aggregation or, perhaps, to re-establish attachment with the substratum. Transfection of ASC-17D Sertoli cells with a 20-base antisense oligonucleotide against clusterin mRNA resulted in extracellular release of LDH and DNA fragmentation. Sertoli cell death by antisense oligonucleotide of clusterin was sequence specific and dose dependent. Treatment of antisense oligonucleotide induced a marked reduction of synthesis for clusterin protein, but not for clusterin mRNA expression, suggesting the translational suppression of clusterin by antisense oligonucleotide. Further, microscopic observation showed that more noticeable cell death was induced by treating the antisense prior to plating the cells than by treating after cell attachment to the plate. From these results, we speculate that down-regulation of clusterin expression in the anchorage-dependent Sertoli cells prevents them from attaching to the plate, and therefore induces cell death.

Animals↗
PubMed2000

Molecular cloning and characterization of the mouse peroxiredoxin V gene.

We have cloned two cDNA isoforms as well as genomic sequences of the mouse Prx V gene and characterized their molecular genetic features. Two isoforms of the mouse Prx V cDNA were identified from liver and testis. The testis-originated long transcripts had extra 1164-bp 5'-UTR sequences compared to the liver-originated short transcripts. Primer extension and sequence analyses revealed that the two isoforms were presumably transcribed at the same gene locus. The gene was composed of six exons spanning 3.2 kb. The short transcript was abundantly expressed in the kidney, liver, and heart of the adult mouse tissues and in the extra-membrane of the 10.5 dpc embryos. The long transcript of 1985 bp was abundantly detected in testis with trace amounts in other tissues. Interestingly, in testis and fetus, only mRNA expression of the long form was identified. However, the protein expression was not found in testis, implying that the long form could not properly direct the protein expression. The long Prx V cDNA has eight uORFs in the extra 5'-UTR, which proceed the major ORF. The inability of protein expression for the long-form cDNA in testis suggests that the uORFs might inhibit translation of the major ORF and thereby confer the tissue-specific regulation of the mouse Prx V gene.

5' Untranslated Regions↗
PubMed2000

Spondylitis is the most common pattern of psoriatic arthritis in Korea.

We assessed the prevalence and clinical features of psoriatic arthritis (PsA) in Korean patients with psoriasis. The prevalence of PsA in patients with psoriasis was 9%. Patients with PsA were older and had a longer duration of skin disease than those with psoriasis alone (median age, 40 vs 35 years, P = 0.03, and 15.3 vs 11.7 years, P = 0.04, respectively). Spondylitis was the most common pattern of PsA (50%). Nail change, dactylitis, and enthesopathy were observed in 36%, 15.4%, and 15.6% of patients with PsA, respectively. Increased erythrocyte sedimentation rate (ESR), antinuclear antibody, and radiological sacroiliitis were more frequent in patients with PsA than in those with uncomplicated psoriasis (25.8% vs 10.3%, P = 0.04; 37.9% vs 16.7%, P = 0.02; and 37.8% vs 1.1%, P < 0.01, respectively). The onset ages of psoriasis and arthritis in the spondylitis group were significantly lower than those in the non-spondylitis group (median age, 21.5 vs 31 years, P = 0.03, and 28.5 vs 43.5 years, P = 0.01, respectively). HLA-B27 was prevalent in 8% of patients with PsA.

Adolescent↗
PubMed2000

Clinical analysis of central islands after laser in situ keratomileusis.

PURPOSE: To analyze the incidence and clinical characteristics of central islands after laser in situ keratomileusis (LASIK) and to elucidate factors associated with their formation. SETTING: Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. METHODS: Laser in situ keratomileusis was performed in 103 eyes of 61 patients with myopia ranging from -4.0 to -13.5 diopters (D) using the Hansatome (Chiron) and SVS Apex Plus (version 3.2.1) excimer laser (Summit Technology) in which the anti-central-island program was implemented. After 1 week, corneal topography (Orbscan, Orbtek) was done and manifest refraction and visual acuity were measured. RESULTS: Postoperatively, the mean uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were 0.12 and 0.06 (logMAR scale), respectively, and the mean refractive error (spherical equivalent) was 0.07 D +/- 0.76 (SD). On topographic examination, a central island was defined as an area of higher refractive power of more than 1.5 D and 2.5 mm or more in diameter. Budding or isolated central islands were observed in 12 eyes of 12 patients (11.7%). The peak, height, and area of the islands were 41.5 +/- 3.1 D, 5.6 +/- 1. 9 D, and 3.5 +/- 1.1 mm(2), respectively. In the eyes with central islands, there were statistically significant differences in the postoperative change in UCVA and BCVA (P <.05). There was no significant correlation between the occurrence of a central island and preoperative refractive error, corneal thickness, age, or in sex and correction of astigmatism (P >.05). CONCLUSION: Despite use of the anti-central-island pretreatment program, the occurrence of central islands after LASIK was significant, as in photorefractive keratectomy. Further studies of the effect of central islands on surgical results and clinical progress and measures to prevent the occurrence are needed.

Adult↗
PubMed2000

Tissue-/stage-dependent expression of a cloned Bombyx mandarina QM homologue.

QM, a novel gene that was firstly isolated as a putative tumor suppressor gene from Wilms' tumor cell line. Although it is well known that the QM gene product plays an important role within the tumor cells, the precise role of QM in the non-tumor cells has remained elusive. With in this mind we isolated a cDNA encoding QM homologue from Bombyx mandarina to understand the function of QM. The 596 bp cDNA has an open reading frame of 219 amino acids and a predicted mol. wt. of 25 kDa. The protein has more than 88% amino acid sequence identity to the QM protein from Drosophila melanogaster. mRNA expression gradually increased from 1-2 days after egg laying to 2 days of finial instar, while very low expressions were detected for either the pupae and the moth stages. The organs, posterior/middle division of silkgland, midgut, fat body and malpighian tubes, also show relatively high mRNA expression levels, respectively. The high degree of conservation and expression of the B. mandarina QM homologous suggest that it has a selectively conserved amino acid sequence due, presumably, to an important biological role which is associated with pupae formation.

Amino Acid Sequence↗
PubMed2000

Functional interaction of general transcription initiation factor TFIIE with general chromatin factor SPT16/CDC68.

BACKGROUND: Transcriptional initiation of class II genes is one of the major targets for the regulation of gene expression and is carried out by RNA polymerase II and many auxiliary factors, which include general transcription initiation factors (GTFs). TFIIE, one of the GTFs, functions at the later stage of transcription initiation. As recent studies indicated the possibility that TFIIE may have a role in chromatin transcriptional regulation, we isolated TFIIE-interacting factors which have chromatin-related functions. RESULTS: Using the yeast two-hybrid screening system, we isolated the C-terminal part of the human homologue of Saccharomyces cerevisiae (y) Spt16p/Cdc68p, a general chromatin factor. The C-terminal part of human SPT16/CDC68 directly interacts with TFIIE, and ySpt16p/Cdc68p also interacts with yTFIIE (Tfa1p/Tfa2p), thus indicating the existence of an evolutionarily conserved interaction between TFIIE and SPT16/CDC68. Functional interaction of yTFIIE and ySpt16p/Cdc68p was examined using a conditional yTFIIE-alpha mutant strain. Over-expression of ySpt16p/Cdc68p suppressed the phenotype of cold sensitivity of the yTFIIE-alpha-cs mutant strain, and in vitro binding assays revealed that yTFIIE-alpha-cs mutant protein showed diminished binding affinity to ySpt16p/Cdc68p. CONCLUSIONS: These observations indicate that general transcription initiation factor TFIIE functionally interacts with general chromatin factor SPT16/CDC68, a finding which provides new insight into the involvement of TFIIE in chromatin transcription. This may well lead to a breakthrough in relationships between the transcription initiation process and structural changes in chromatin.

Amino Acid Sequence↗
PubMed2000

Association between hepatitis B virus infection and HLA-DR type in Korea.

Although the mechanism of susceptibility to chronic persistent hepatitis B virus (HBV) infection is not well clarified, immunogenetic factors of the host may have a role. Recently, a strong association between HLA-DR13 and the self-limited course of HBV infection has been reported. To determine whether the elimination of HBV is related to a particular HLA allele, we studied the HBV markers and HLA-DR phenotypes of 1,272 Koreans who had visited Yonsei University Medical Center for renal transplantation. They included 330 renal transplant donors. Subjects were categorized into 3 different groups: the "Unexposed Group" (UE; n = 946) with negative HBV markers, the "Chronic Carrier Group" (CC; n = 83), who were hepatitis B surface antigen (HBsAg)-positive, and the "Spontaneously Cleared Group" (SC; n = 243), who were HBsAg-negative with antibodies to HBsAg (anti-HBs) and hepatitis B core antigen (anti-HBc). HLA-DR4 was the most common type in all groups. HLA-DR6 was significantly more frequent in 69 of 243 subjects with SC (28. 4%) than in 8 of 83 subjects with CC (9.6%) (P <.001; relative risk [RR] = 3.72). HLA-DR9 was significantly more frequent in CC than in SC (P <.001; RR = 0.33). HLA-DR13 showed a stronger association with the clearance of HBV than the other HLA-DR6 subgroup. The distribution of HLA-DR phenotypes was similar regardless of renal disease. Our data indicate that HLA-DR6, especially HLA-DR13, is one of the host factors, which influences the immune response to HBV, and may be associated with self-elimination of HBV in Koreans.

Adult↗
PubMed2000

Takayasu's arteritis concurrent with Marfan syndrome--a case report.

Marfan syndrome (MS) is a dominantly inherited connective tissue disorder characterized by arachnodactyly, tall stature, the presence of aortic aneurysm, and lens dislocation. Takayasu's arteritis (TA) is a chronic vasculitis that primarily affects the aorta and its branches. The authors report the first case of TA in a patient with MS. The simultaneous presence of TA and MS could be a coincidence, however; the pathogenesis of TA might be linked with autoimmunity induced by abnormal extracellular matrix protein derived from the genetic mutations in MS.

Adult↗
PubMed2000

Maximum insufflation capacity.

OBJECTIVE: To investigate the effect of deep lung insufflations on maximum insufflation capacities (MICs) and peak cough flows (PCFs) for patients with neuromuscular disease. METHOD: Forty-three patients with neuromuscular disease were trained in stacking delivered volumes of air to deep lung insufflation and were prescribed a program of air stacking once their vital capacities (VCs) were noted to be < 2,000 mL. VC, MIC, and unassisted and assisted PCF were monitored. The initial data were compared with the highest MICs subsequently achieved. For those patients whose MICs only decreased, we compared the initial data with the most recent data. RESULTS: The MICs increased from (mean +/- SD) 1,402 +/- 530 mL to 1,711 +/- 599 mL (p < 0.001) for 30 patients and only decreased for 13 patients. Patients for whom the MICs increased also had a significant increase in assisted PCF from 3.7 +/- 1.4 to 4.3 +/- 1.6 L/s (p < 0.05) despite having somewhat decreasing VCs and unassisted PCFs. CONCLUSION: With training, the capacity to stack air to deep insufflations can improve despite progressive neuromuscular disease. This can result in increased cough effectiveness.

Adult↗
PubMed2000

Capsular polysaccharide typing of domestic mastitis-causing Staphylococcus aureus strains and its potential exploration of bovine mastitis vaccine development. I. Capsular polysaccharide typing, isolation and purification of the strains.

One hundred seven isolates of Staphylococcus aureus from bovine mastitis were investigated for colony morphology in serum-soft agar (SSA), autoagglutination in salt, and capsular serotype. Capsular polysaccharide (CP) was purified and quantified from the extracts of clinical isolates. Overall, 89 isolates (83.2%) were diffuse in the SSA, without any difference in the proportion of diffuse colony between type 5 and type 8 strains. Some strains exhibited compact colonies in the SSA and expressed CP as determined by an enzyme-linked immunosorbent assay, indicating that compact morphology does not exclude encapsulation. The majority of the strains (11/12) showed autoagglutination in the salt aggregation test. The serotype 336 accounted for 46.7% of the isolates followed by serotype 5 (12.1%) and serotype 8 (12.1%). Particularly, twenty-six (24.3%) isolates reacted with two serotypes; 7 for type 8/336 and 19 for type 5/336. Five isolates (4.7%) were nontypeable with monoclonal antibodies specific for CP serotype 5, 8, or 336. The CP concentration in culture supernatants varied with the serotypes, and the total amount of CP produced by cells grown in a liquid medium was much less than that produced by cells grown on a solid medium. The Western blotting indicated that the CP bands of S. aureus serotype 5 and 8 were ranged in the molecular mass of 58-84 kilodalton (kDa), with additional bands in the region of approximately >/= 48 or </= 84 kDa.

Agglutination Tests↗
PubMed1999

Guanosine 5',3'-cyclic monophosphate enhances lipopolysaccharide-induced nitric oxide synthase expression in mixed glial cell cultures of rat.

Primary mixed glial cell cultures treated with lipopolysaccharide (LPS; 1.0 microg/ml) showed biphasic increases of inducible nitric oxide synthase (iNOS) mRNA expression 6 h and 24-36 h after LPS treatment. Dibutyryl-guanosine 5',3'-cyclic monophosphate (db-cGMP; 1.0 mM) enhanced the second phase of the LPS-induced iNOS expression 24 and 30 h after LPS stimulation. KT5823 (1.0 microM), a protein kinase G (PKG) inhibitor, inhibited the LPS-induced iNOS expressions at 24 and 30 h and their enhancements caused by db-cGMP. In astrocyte-enriched cultures with reduced microglial contamination, the LPS-induced iNOS expression was decreased, though slightly enhanced by db-cGMP. These results suggest that cGMP/PKG signaling may be involved in the second phase of the LPS-induced glial iNOS expression and its upregulation, which are apparent in the presence of microglial cells.

Alkaloids↗
PubMed1999

Rapid degradation of PrxI and PrxII induced by silica in Rat2 cells.

Peroxidases of the peroxiredoxin (Prx) family catalyze the reduction of H(2)O(2) and lipid peroxides. The effects of H(2)O(2), 12-O-tetradecanoylphorbol 13-acetate (TPA), and silica on the abundance of two cytosolic isoforms of Prx (PrxI and PrxII) were examined in Rat2 cells. TPA induces the production of reactive oxygen species (ROS) in various mammalian cell types, and silica induces the production of ROS in Rat2 cells. Whereas H(2)O(2) and TPA did not affect the concentration of PrxI or Prx II, silica triggered a rapid degradation of both Prx enzymes. Silica also induced degradation of the NF-kappaB inhibitor IkappaB-alpha. N-Acetylcysteine and diphenyleneiodonium, both of which inhibit the accumulation of intracellular ROS, each blocked silica-induced degradation of IkappaB-alpha but had no effect on that of the Prx enzymes, suggesting that ROS do not contribute to Prx proteolysis. The silica-induced degradation of Prx enzymes was also insensitive to the proteasome inhibitors MG132 and lactacystin, whereas IkappaB-alpha proteolysis was completely blocked by these inhibitors. Experiments with the Ca(2+) ionophore A23187 indicated that a Ca(2+)-dependent protease such as calpain might contribute substantially to silica-induced degradation of PrxII, but only moderately to that of PrxI. These results indicate that silica increases cellular oxidative stress not only by inducing ROS production, but also by triggering the degradation of Prx enzymes that are responsible for elimination of cellular ROS. Such aggravated oxidative stress might be important in the initial pathogenesis of silica-associated pulmonary diseases.

Animals↗
PubMed1999

Protein kinase CKII interacts with and phosphorylates the SAG protein containing ring-H2 finger motif.

To investigate the biological function of CKII, we have identified proteins that interact with the subunits of CKII using the yeast two-hybrid system. Here we report that SAG, an antioxidant protein containing Ring-H2 finger motif, is a cellular partner associating with the beta subunit of CKII. SAG does not interact with the alpha subunit of CKII. Analysis of SAG deletion mutants indicates that the Ring-H2 motif of SAG is necessary and sufficient for its binding to the beta subunit of CKII. Recombinant SAG can be phosphorylated by CKII in vitro, providing evidence that the beta subunit mediates the interaction of CKII enzyme with substrate proteins. Overlay experiment shows that SAG and the beta subunit of CKII associate directly in vitro and that CKII-mediated phosphorylation of SAG does not affect the interaction between SAG and the beta subunit of CKII. Northern blot analysis indicates that both SAG and the beta subunit of CKII were relatively rich in human heart, liver, skeletal muscle, and pancreas, but were detected in only trace amounts in brain, placenta, and lung. Our present results suggest that CKII may play a role in the regulation of SAG function.

Calcium-Calmodulin-Dependent Protein Kinase Type 2↗