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Biomedical subjects

Y S Hong

Publications and source records attributed to Y S Hong.

At least 19 recordsLinked to original sources
PubMed1997

The impact of HLA-DRB1*0405 on disease severity in Korean patients with seropositive rheumatoid arthritis.

Many reports have described HLA-DRB1 genes as having an influence on disease severity and susceptibility in rheumatoid arthritis (RA). Studies were undertaken to define the effect of RA-associated alleles on disease severity in Korean patients with seropositive RA. The results indicate that the most common RA susceptibility allele, HLA-DRB1*0405, is significantly associated with bony erosion, joint deformity and extra-articular manifestations. However, RA-associated alleles in Koreans have less effect on nodular disease than in Caucasians. This suggests that the presence of RA-associated alleles, especially HLA-DRB1*0405, seems to be a prognostic marker for severe erosive disease in Koreans.

Adult↗
PubMed1996

Identification of two mutations in a compound heterozygous child with dihydrolipoamide dehydrogenase deficiency.

An infant girl with elevated blood lactate, pyruvate, and plasma branched-chain amino acids was diagnosed with dihydrolipoamide dehydrogenase (E3; dihydrolipoamide: NAD+ oxidoreductase, EC 1.8.1.4) deficiency. Activities of the pyruvate dehydrogenase complex and E3 from patient were 26 and 2% of controls in blood lymphocytes, and 11 and 14% in cultured skin fibroblasts, respectively. Western blot analysis demonstrated that the amount of E3 protein in fibroblasts from the patient and her father was about half of controls, while Northern blot analysis showed normal amounts of E3 RNA. DNA sequencing of cloned full-length E3 cDNAs from the patient revealed two mutations in separate alleles. One is a single base insertion of an extra adenine in the last codon of the leader peptide sequence (TAC-->TAAC) leading to a nonsense mutation which results in the premature termination of the precursor E3 polypeptide (Y35X). The other is a missense mutation due to substitution of guanine for adenine, causing an Arg-->Gly substitution at amino acid 460 of the mature protein (R460G) which triggers the loss of E3 activity probably by structural change in the E3 dimer. DNA sequencing of E3 cDNAs from the parents demonstrated that the nonsense mutation was inherited from the father and the missense mutation was inherited from the mother.

Alleles↗
PubMed1996

Selective inhibition of polymorphonuclear leukocytes by immunosuppressive concentration of prostaglandin E2.

Prostaglandin E2(PGE2) has been implicated as an immunosuppressive agent and plasma levels of PGE2 are elevated in patients sustaining thermal injury. We examined the effect of 10(-7) M prostaglandin E2(PGE2) on human polymorphonuclear leukocytes (PMN) to determine whether it directly inhibits stimulated responses of these cells. At this concentration, PGE2 alone was incapable of stimulating PMN intracellular hydrogen peroxide production (indirectly assayed by fluorescence of 2',7'-dichlorofluorescin) or expression of the PMN CD11b/CD16 surface glycoproteins. PMN incubated in the presence of the soluble stimuli phorbol myristate acetate(PMA, 100 ng/ml) or recombinant human C5a(rHC5a, 10(-8) M) generated significant amounts of hydrogen peroxide, increased their CD11b expression and decreased their CD16 expression. Pre-incubation of cells with PGE2 caused significant inhibition of all the observed changes stimulated by rHC5a. In contrast, events stimulated by PMA were not affected by preincubation of cells with PGE2. We conclude that PGE2, in concentrations identical to those found in the plasma of patients with burn injuries, is capable of selectively inhibiting some stimulated events and phenotypic expression of PMN in vitro study.

Dinoprostone↗
PubMed1996

New anthracycline metabolites produced by the aklavinone 11-hydroxylase gene in Streptomyces galilaeus ATCC 31133.

Transformation of Streptomyces galilaeus ATCC 31133 with the aklavinone 11-hydroxylase gene (dnrF) resulted in the production of many red pigments. The new metabolites were purified and their structures were determined as 11-hydroxylated aclacinomycin A, B and T by spectral analysis. This result indicated that the dnrF was stably expressed in the strain S. galilaeus ATCC 31133 to give rise to hybrid aclacinomycins. In addition, a new aclacinomycin analog named 11-hydroxyaclacinomycin X was isolated from the same culture. Its structure was elucidated as 2"'-amino-11-hydroxyaclacinomycin Y. It showed strong cytotoxicity against several human tumor cell lines, especially leukemia and melanoma cell lines.

Aclarubicin↗
PubMed1995

Structure and function of the HOX A1 human homeobox gene cDNA.

Homeobox genes code for transcription factors and are arranged in clusters, named A, B, C and D, found on four separate chromosomes in vertebrates. They contain a homeobox DNA sequence which codes for the homeodomain, a region of amino acids responsible for the DNA binding exhibited by these proteins. During embryonic development, the homeobox genes are both spatially and temporally regulated. In teratocarcinoma cell cultures, homeobox genes are regulated by retinoic acid (RA). The cDNAs from the first gene in the human HOX A cluster, HOX A1 (1.6), were cloned and the nucleotide sequence of a full-length cDNA was determined. It is highly homologous to its murine counterpart. Another HOX A1 cDNA was cloned, corresponding to an alternatively spliced form. In vitro translation of the full-length cDNA clone gave rise to a protein of 36 kDa. In PA-1 human teratocarcinoma cells HOX A1 is the earliest HOX A gene to be expressed after treatment with RA. To test whether HOX A1 could function as a early regulator of other HOX A cluster genes, we cotransfected into PA-1 human teratocarcinoma cells sense and antisense HOX A1 cDNAs expressed from an SV40 promoter with a 5.4-kb RA-sensitive HOX A4 (1.4) promoter-cat reporter. We found no effect of HOX A1 on the HOX A4 promoter. However, cotransfection of HOX A5 (1.3) was able to inhibit the HOX A4 promoter activity.

Alternative Splicing↗
PubMed1995

Cloning and expression of the heterodimeric deoxyguanosine kinase/deoxyadenosine kinase of Lactobacillus acidophilus R-26.

Two uniquely paired deoxynucleoside kinases, deoxycytidine kinase/deoxyadenosine kinase (dCK/dAK) and deoxyguanosine kinase/deoxyadenosine kinase (dGK/dAK) are required, together with thymidine kinase (TK), for deoxynucleotide synthesis in Lactobacillus acidophilus R-26. Using polymerase chain reaction-generated probes based on N-terminal amino acid sequences, we have cloned tandem genes for 25- and 26-kDa polypeptides, whose derived amino acid sequences and size correspond to wild-type Lactobacillus enzyme subunits. Expression in Escherichia coli uses a single endogenous promoter and yields active dGK/dAK (approximately 3% of extracted protein) closely resembling wild-type dGK/dAK in specificity, kinetics, heterotropic activation, and end product inhibition. Alignment of cloned genes reveals 65% identity in their DNA sequences and 61% identity in derived amino acid sequences. Comparison with herpes-viral TKs reveals three conserved regions: glycine- and arginine-rich ATP-binding motifs and a D/E-R-S/H motif at the putative TK deoxynucleoside site. Greater homology, however, is seen upon multiple alignment of dGK with mammalian deoxycytidine kinases, yielding the consensus sequence-D/E-R-S-I/V-Y-x-D-.dGK also shares a sequence (-Y-D-P-T-I/L-E-D-S/Y-Y-) required for GTP hydrolysis by p21ras.

Amino Acid Sequence↗
PubMed1995

Directed mutagenesis of deoxyguanosine site at arginine 79 up-regulates turnover on deoxyadenosine kinase subunit of heterodimeric enzyme from Lactobacillus acidophilus R26.

Examination of conserved motifs on the cloned subunits of the deoxyguanosine kinase/deoxyadenosine kinase (dGK/dAK) of Lactobacillus acidophilus R-26 has begun with the Asp-Arg-Ser (DRS) motif. Replacement of Asp-78 of both subunits with Glu, Ala, or Asn reduced dGK and dAK activities to less than 0.2%, whereas replacement of Arg-79 with Lys, either on both subunits in tandem (R79K), or on the dGK subunit only (R79K:dGK), yielded active but kinetically modified enzymes. These were partially purified, and their kinetic and regulatory properties were analyzed. For dAK activity, the Vmax of the R79K:dGK enzyme was increased 28-fold, with no change in the limiting Km for dAdo, but with a slightly reduced Km for MgATP. The V/K efficiency ratio of dAK was also increased 29-fold, but that of dGK was decreased to 5-10% due to a 10-fold increase in Km for dGuo and a reduced Vmax. Therefore, the R79K substitution seems to have a greater effect on dGuo binding than on that of dAdo, but dGK modification appears to produce a stimulatory conformational effect on the opposite subunit, resembling the known unidirectional activation of dAK by either dGuo or dGTP.

Base Sequence↗
PubMed1995

Expression of Streptomyces peucetius genes for doxorubicin resistance and aklavinone 11-hydroxylase in Streptomyces galilaeus ATCC 31133 and production of a hybrid aclacinomycin.

The aklavinone 11-hydroxylase gene and two doxorubicin resistance genes cloned from Streptomyces peucetius subsp. caesius ATCC 27952 were introduced into doxorubicin-sensitive Streptomyces galilaeus ATCC 31133, an aclacinomycin producer. The doxorubicin resistance genes drrA and drrB endowed S. galilaeus with high-level resistance to doxorubicin, indicating that the resistance mechanism for doxorubicin might be different from that for aclacinomycin A. Transformation of S. galilaeus ATCC 31133 with plasmid pMC213 containing the aklavinone 11-hydroxylase gene (dnrF) resulted in the production of many red pigments. A new metabolite was purified, and the position of the newly introduced hydroxyl group was determined. This result indicated that the aklavinone 11-hydroxylase gene was stably expressed in S. galilaeus ATCC 31133 and that it gave rise to a hybrid aclacinomycin A which showed highly specific in vitro cytotoxicity against leukemia and melanoma cell lines.

Aclarubicin↗
PubMed1994

Molecular cloning and characterization of the aklavinone 11-hydroxylase gene of Streptomyces peucetius subsp. caesius ATCC 27952.

The gene encoding aklavinone 11-hydroxylase of Streptomyces peucetius subsp. caesius ATCC 27952 was cloned and sequenced. The deduced amino acid sequence of the gene contains at least two common motifs of well-conserved amino acid sequences of several flavin-type bacterial hydroxylases. The hydroxylase gene is apparently transcribed from a single transcriptional start point. The phenotype of a dnrF mutant generated by gene disruption supports the idea that the dnrF gene encodes aklavinone 11-hydroxylase.

Amino Acid Sequence↗
PubMed1992

Polymorphonuclear leukocyte functions enhanced by chemotaxis.

Human polymorphonuclear leukocytes (PMN) migrate into tissues in response to chemoattractants, yet it is not known whether this process alters the functional capabilities of the PMN. Using recombinant human interleukin-8 (rHIL-8, 100 ng/ml) as a stimulus, we compared a population of PMN that migrated through a polyvinylpyrrolidone-coated polycarbonate filter containing 8.0 microns diameter pores with PMN stimulated in suspension. PMN were analyzed by flow cytometry according to functional and phenotypic criteria. CD11b/CD16 expression was unaltered by chemotaxis. In contrast, chemotaxis enhanced phagocytosis of E. coli, independent of opsonization with IgG. Similarly, chemotaxis increased baseline hydrogen peroxide production. We conclude that the chemotactic motion of PMN "primes" the cell for increased oxidative burst activity and augments the ability of PMN to ingest bacteria. This increased functional capability is distinct from rHIL-8 stimulation and appears to be independent of complement-and Fc-receptor expression.

Antigens, CD↗
PubMed1992

Effects of buthionine sulfoximine treatment on cellular glutathione levels and cytotoxicities of cisplatin, carboplatin and radiation in human stomach and ovarian cancer cell lines.

Chemotherapy failure remains a significant medical problem in the treatment of neoplastic disease and is thought to be due to many different factors including membrane transport, p-glycoprotein in multidrug resistance, glutathione and its related enzymes, topoisomerase II and DNA repair. Glutathione is a major constituent of non-protein thiol and participates in detoxification of chemotherapy and radiation. Thus, glutathione concentration is correlated with sensitivity to alkylating agents and radiation, and increased in resistant cell lines. Buthionine sulfoximine (BSO) is an inhibitor of glutathione biosynthesis and may increase cytotoxicities of alkylating agents, including melphalan and cisplatin, and radiation in sensitive and resistant cell lines. We studied effects on cellular glutathione levels and cytotoxicities of cisplatin, carboplatin and radiation by BSO treatment in human stomach cancer cell line (SNU-1) and ovarian cancer cell line (OVCAR-3). The results were as follow: 1) After BSO treatment of 1 mM and 2 mM for 2 days, the intracellular thiol concentration was depleted to 75.7% and 76.2% in SNU-1, and 74.1% and 63.0% in OVCAR-3, respectively. 2) The intracellular thiol concentration in SNU-1 was depleted to 33.4% after BSO 2 mM for only 2 hours incubation and 71.5% after small amount of BSO (0.02 mM) for 2 days. 3) The recovery of intracellular thiol concentration required more than 3 days after BSO removal. 4) BSO inhibited partially the growth of SNU-1 and OVCAR-3. 5) The cytotoxicities of cisplatin and carboplatin were markedly enhanced both in SNU-1 and OVCAR-3 by BSO treatment. 6) The cytotoxicities of radiation was increased in OVCAR-3 and SNU-1 by BSO treatment. Therefore, it is concluded that BSO can deplete effectively the intracellular thiol concentration and enhance the cytotoxicities of cisplatin, carboplatin and radiation.

Antimetabolites, Antineoplastic↗
PubMed1992

Modulation of the endotoxin receptor (CD14) in septic patients.

The monocyte is a pivotal cell in septic patients that responds to endotoxin with release of inflammatory cytokines. Monocytes display on their surface a receptor (CD14) for complexes formed by endotoxin (lipopolysaccharide, LPS) and a plasma LPS-binding protein (LBP). We compared monocytes obtained from normal controls with those obtained from septic patients for expression of CD14 by flow cytometric analysis of immunofluorescent-stained cells. In normal individuals and patients, 75%-95% of monocytes are CD14 positive (CD14+). Mean fluorescence exhibited by the CD14+ population was measured after maintaining cells at 37 degrees C for 15 minutes and compared with baseline cells held at 4 degrees C (mean fluorescence ratio). All cells increased their CD14 mean fluorescence ratio with warming; however, the level achieved by monocytes obtained from septic patients was on average 78% +/- 8% of control levels (p = 0.014). To further clarify CD14 expression, we examined the effect of Escherichia coli LPS on normal monocytes by comparing monocytes treated in serum-free buffer (no LBP) with monocytes treated in whole blood (containing LBP). The LPS (1.0 ng/mL) incubated with whole blood for 120 minutes generated an increase in CD14+ mean fluorescence compared with buffer. In contrast, phorbol myristate acetate lowered CD14+ mean fluorescence levels. These data indicate that normal monocytes incubated in the presence of ligand (LBP-LPS complexes) increase their expression of CD14, whereas CD14 expression in septic patients is diminished. We conclude that monocytes from septic patients were responsive to other stimuli aside from LPS and that decreased expression of CD14 may indicate a poor prognosis.

Antigens, CD↗
PubMed1992

[Clinical study of yi shen ning for treatment of kidney-yang deficiency after hormone withdrawal of primary nephrotic syndrome--clinical analysis of 100 cases].

This paper reports that Yi Shen Ning (YSN) which acts as warming and tonifying Kidney-Yang was administrated on 100 cases of primary nephrotic syndrome (PNS) while adrenocortical hormone (ACTH) was diminished to half dosage. The results showed that to apply the integrated TCM and WM according to the different stage of PNS was quite effective to treat deficient syndrome of Kidney-Yang appeared after withdrawal of ACTH. This recipe not only could improve the symptoms, but also pick plasma cortisol up earlier than expected, which was inhibited by exogenous hormone. The total remission rate of YSN group was 68.75%, higher than that of ACTH group (P < 0.05), especially for the cases dependent on exogenous hormone, the re-acquired remission rate reached to 58.3%.

Adult↗
PubMed1991

Alteration of homeobox gene expression by N-ras transformation of PA-1 human teratocarcinoma cells.

We used a series of cell clones from a human teratocarcinoma cell line, PA-1, to study the effect of transformation by an activated N-ras oncogene on the expression of genes involved in retinoic acid (RA)-induced differentiation and growth regulation. Recently, it has been shown that expression of human HOX 2 genes is sequentially activated by RA beginning from Hox 2.9 at the 3' end of the HOX 2 cluster (A. Simeone, D. Acampora, L. Arcioni, P. W. Andrews, E. Boncinelli, and F. Mavilio, Nature [London] 346:763-766, 1990). We now report that six different genes of the cluster HOX 1 are sequentially induced by RA in a similar temporal pattern, beginning with genes at the 3' end of the cluster. However, in N-ras-transformed cell clones, RA-induced expression of these homeobox genes is delayed. Hox 1.4 and Hox 1.3, genes abundantly induced in nontransformed clones after 3 days of RA treatment, are expressed in N-ras-transformed cells only after 10 days of RA treatment. At this time, the cells' growth is arrested at very high density, and no differentiated morphologic characteristics are observed. Constitutive expression of a transfected Hox 1.4 gene under the control of a simian virus 40 promotor leads to differentiated cell morphology similar to that of the RA-induced phenotype and restores the growth-inhibitory effects of RA in N-ras-transformed cells. These observations provide evidence that enhanced proliferation in N-ras-transformed cells compromises teratocarcinoma cell differentiation by a mechanism that transiently suppresses homeobox gene induction and implies a central role for homeobox genes in RA-induced cell differentiation. We conclude that stimulation of a putative growth factor signal pathway, associated with ras-induced proliferation, transiently suppresses the induction of transcription factors functionally involved in cell growth and differentiation.

Amino Acid Sequence↗
PubMed1990

[An operations study on a home health nursing demonstration program for the patient discharged with chronic residual health care problems].

The study was conceived in relation to a concern over the growing gap between the needs of chronic patients and the availability of care from the current health care system in Korea. Patients with agonizing chronic pain, discomfort, despair and disability are left with helplessly unprepared families with little help from the acute care oriented health care system after discharge from hospital. There is a great need for the development of an alternative means of quality care that is economically feasible and culturally adaptable to our society. Thus, the study was designed to demonstrate the effectiveness of home health care as an alternative to bridge the existing gap between the patients' needs and the current practice of health care. The study specifically purports to test the effects of home care on health expenditure, readmission, job retention, compliance to health care regime, general conditions, complications, and self-care knowledge and practices. The study was guided by the operations research method advocated by the Primary Health Care Operations Research Institute (PRICOR) which constitutes 3 stages of research: namely, problem analysis solution development, and solution validation. The first step in the operations research was field preparation to develop the necessary consensus and cooperation. This was done through the formation of a consulting body at the hospital and a steering committee among the researchers. For the stage of problem analysis, the Annual Report of Seoul National University Hospital and the patients records for last 5 years were reviewed and selective patient interviews were conducted to find out the magnitude of chronic health problems and areas of unmect health care needs to finally decide on the kinds of health problems to study. On the basis of problem analysis, the solution development stage was devoted to home care program development asa solution alternative. Assessment tools, teaching guidelines and care protocols were developed and tested for their validity. The final stage was the stage of experimentation and evaluation. Patients with liver diseases, hemiplegic and diabetic conditions were selected as study samples. Discharge evaluation, follow up home care, measurement and evaluation were carried out according to the protocols of care and measurement plan for each patient for the period of 6 months after discharge. The study was carried out for the period from Jan. 1987 to Dec. 1989. The following are the results of the study presented according to the hypotheses set forth for the study; 1.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronic Disease↗
PubMed1989

Structure of the human thyroid peroxidase gene: comparison and relationship to the human myeloperoxidase gene.

All exons of the human thyroid peroxidase gene were cloned from phage and cosmid libraries and sequenced, including 2599 base pairs of upstream DNA. The gene contains 17 exons and covers at least 150 kilobase pairs of chromosome 2. The transcription start site was identified by both S1 mapping and primer extension; a typical TATA box was found 25 bases upstream of the putative start site. A comparison of the gene structures of thyroid peroxidase and a granulocyte protein, myeloperoxidase, revealed that the positions of the 3rd through 11th exon-intron junctions in thyroid peroxidase coincide exactly with those of the 2nd through 11th exon-intron junctions in myeloperoxidase except the 7th myeloperoxidase junction, that does not have any counterpart in thyroid peroxidase. The amino acid codon separation pattern in each junction is well conserved between both enzymes. Four exons, unique to thyroid peroxidase, are located at the 3' end of the gene (exons 13-16), each of which encompasses a different protein module. Three of these modules, representing exons 13, 14, and 15, bear significant similarities to C4b-beta 2 glycoprotein, the EGF-LDL receptor, and a typical transmembrane domain, respectively. The genes coding for these modules were probably fused to an ancestral peroxidase gene to generate the present thyroid peroxidase gene. The data suggest that intron loss, and/or insertion, and exon shuffling have played important roles in the evolution of the thyroid peroxidase gene.

Amino Acid Sequence↗