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Biomedical subjects

S G Lee

Publications and source records attributed to S G Lee.

At least 55 records · Page 3Linked to original sources

Health development experience in North and South Korea.

The purpose of this study is to compare the difference in health status between South Koreans and North Koreans and to identify factors responsible for the remarkable improvements in the health status of South Koreans. In order to examine the causes of the difference in health level, the health indices and their determinants of two Koreas were analyzed in time order. As of the year 2000, the average life expectancy at birth is 71.0 years for men and 78.6 years for women in South Korea, which is longer than that of North Korea by 8.1 for men and 11.2 for women. Infant mortality rate in 1998 was 9.0 per 1,000 live births in South Korea and 54.0 in North Korea. Since being liberated from Japanese ruling in 1945, South Korea has achieved remarkable economic growth under democracy and a market economy system. On the other hand, North Korea has maintained a socialistic system. North Korea has suffered from economic crisis since the 1990s. From this point it could be said that economic status is the major factor for the differences in health level between the two Koreas. Economic status not only directly influences health level but also indirectly affects it through influences on nutrition, hygiene, health resources, and other intervening factors. The South Korean government has concentrated its limited resources on public health activities such as tuberculosis control, family planning (FP), and maternal and child health (MCH) programmes whereas the private sector has taken charge of constructing the health delivery system including health facilities and human resources. In order to solve the problem, which might occur in the private-oriented medical care system, the South Korean government has introduced the national health insurance programme and enforced regulation policies. Many developing countries which are suffering from poverty and disease, can learn from the experience of Korea that had suffered from similar problems up to the early 1970s.

Delivery of Health Care↗

Interaction of human Ku70 with TRF2.

Ku, a heterodimer of 70- and 80-kDa subunits, plays a general role in the metabolism of DNA ends in eukaryotic cells, including double-strand DNA break repair, V(D)J recombination, and maintenance of telomeres. We have utilized the yeast two-hybrid system to identify Ku70-interacting proteins other than Ku80. Two reactive clones were found to encode the dimerization domain of TRF2, a mammalian telomeric protein that binds to duplex TTAGGG repeats at chromosome ends. This interaction was confirmed using bacterial fusion proteins and co-immunoprecipitations from eukaryotic cells overexpressing TRF2. The transfected TFR2 colocalized with Ku70.

Animals↗

Expression of transforming growth factor-alpha mRNA in livers of patients with chronic viral hepatitis and hepatocellular carcinoma.

BACKGROUND: Transforming growth factor-alpha (TGFalpha) is an important autocrine growth factor of hepatocytes. The authors evaluated the roles of TGFalpha in chronic viral hepatitis (CVH) and hepatocellular carcinoma (HCC). METHODS: The authors measured the amounts of TGFalpha mRNA in liver tissues from 18 patients with HCC, 31 patients with CVH, and 7 normal controls. " Hot-start" reverse transcription-polymerase chain reaction (RT-PCR) using oligo-dT and specific primers detected TGFalpha mRNA in total cellular RNA extracted from liver tissues. The levels of TGFalpha mRNA were determined by the end point titers of serial, two-fold dilutions of cDNA. The amounts of hepatitis B virus RNA (HBV-RNA) in livers of patients with chronic hepatitis B also were measured by Northern blot hybridization. RESULTS: TGFalpha mRNA levels were extremely higher in patients with HCC compared with patients with CVH and normal controls, and the levels in patients with CVH also were elevated compared with normal controls. The levels of TGFalpha mRNA were overexpressed in the underlying livers of patients with HCC compared with patients with CVH, although they were lower than those found in HCC tissues. The levels of TGFalpha mRNA were higher in samples from patients with chronic hepatitis B than in samples from patients with chronic hepatitis C. The levels of TGFalpha mRNA were not correlated with serum alanine aminotransferase or HBV-RNA levels in liver tissues in patients with chronic hepatitis B. However, the expression of TGFalpha mRNA tended to be higher in the livers of patients with raised serum alpha-fetoprotein levels. CONCLUSIONS: The overexpression of TGFalpha mRNA in the liver seems to be associated with the regeneration of hepatocytes rather than hepatic necrosis or viral replication. Also, it may be related closely to the development or progression of HCC, especially in the livers of patients with chronic hepatitis B.

Adult↗

Identification and characterization of a bidirectional promoter from the intergenic region between the human DDX13 and RD genes.

The human DDX13 gene encodes a putative RNA helicase of the DExH-box family. In an earlier report we showed that the human DDX13 and RD genes were arranged head-to-head in the class III MHC complex and their ATG start codons were separated by 745 base pairs. We have now analyzed the common 745 bp intergenic region in detail and characterized their promoters. Northern blot analysis revealed that DDX13 and RD exhibit distinct patterns of steady-state expression among multiple human tissues. The promoter regions for DDX13 and RD genes were identified by deletion analysis from 740 bp to 176 bp of the intergenic region fused to a chloramphenicol acetyltransferase (CAT) reporter gene using transient transfection assays. Results indicated that a promoter sequence as small as 176 bp is sufficient for basal expression of both genes in HeLa and HepG2 cells. Functional analysis using a bidirectional reporter system demonstrates that the sequence 262 bp proximal to the DDX13 gene is sufficient for concurrent expression in both directions. However, the common 740 bp intergenic region showed promoter activity in DDX13 only, suggesting the presence of a negatively acting region for the RD gene within the region -267 to -744. It appears that RD expression is controlled by a complex system of positively and negatively acting elements present on distant portions of both genes.

Blotting, Northern↗

Transcriptional repression of the human p53 gene by hepatitis B viral X protein.

Hepatitis B viral X protein (HBx) and the human p53 protein (p53) have been known as a transactivator and as a tumor suppressor, respectively. These two proteins have also been known to interact with each other to neutralize their authentic functions and the p53 represses the HBV enhancer/X promoter activity. Here we report that the promoter activity of the human p53 gene was strongly repressed by the HBx using the chloramphenicol acetyl transferase (CAT) assay. Analyses of serial deletion, site-directed mutagenesis and the heterologous promoter system showed that the site responsible for the repression was the E-box element in the promoter of the p53 gene. In addition, HBx as expected also repressed the activation of the p53 promoter by c-Myc through the E-box element. Northern blot analyses also showed that the expression of the p53 gene in the HepG2-K8 cell line, which expresses HBV genes including HBx, was much more repressed than that of the control cell HepG2. These results with previous data suggest that the shift of the reciprocal inhibitory activities at the levels of protein-protein interaction and transcription between HBx and p53 may play a decisive role in the HBV-related hepatocarcinogenesis.

Genes, myc↗

Hepatobiliary scintigraphy in the assessment of biliary obstruction after hepatic resection with biliary-enteric anastomosis.

We investigated the usefulness of hepatobiliary scintigraphy (HBS) for diagnosing biliary obstruction after curative hepatic resection with biliary-enteric anastomosis. The study population consisted of 54 patients who underwent surgery for benign (n=18) or malignant (n=36) biliary disease. We analysed 68 technetium-99m DISIDA scintigrams which were performed at least 1 month after the surgery (median: 9 months). Final diagnosis was made by operative exploration, other invasive radiological studies or clinical and radiological follow-up for at least 6 months after the surgery. Diagnostic accuracy was analysed according to the pretest likelihood of biliary obstruction. There were two total and 15 segmental biliary obstructions. In patients with symptoms of biliary obstruction and abnormal liver function, HBS always allowed correct diagnosis (two instances of total obstruction, seven of segmental obstruction and seven of non-obstruction). Among the patients with nonspecific symptoms or isolated elevation of serum alkaline phosphatase, HBS diagnosed segmental biliary obstruction in seven of the eight instances, and non-obstruction in 22 of 23 instances. There were no cases of biliary obstruction and no false-positive results of HBS in 21 instances with no clinical signs or symptoms of biliary obstruction. The diagnostic sensitivity and specificity of HBS for biliary obstruction were 94% (16/17) and 97% (50/51), respectively. In conclusion, HBS is a highly accurate modality for the diagnosis of segmental biliary obstruction during long-term follow-up after hepatic resection with biliary-enteric anastomosis.

Biliary Tract Surgical Procedures↗

One hundred and eleven liver resections for hilar bile duct cancer.

A positive correlation between absence of residual tumor at resection margins and long-term survival in the treatment of hilar bile duct carcinoma has encouraged some surgeons to use a more radical approach, including liver/portal vein resection and combined pancreatoduodenectomy. However, if liver resection is associated with significant morbidity and mortality, it may not produce any overall benefit. This review was undertaken in an attempt to determine whether liver resection is a safe procedure and whether if has any beneficial effect over that of local bile duct excision alone, in terms of achieving curative resection and long-term survival. The records of 151 patients with hilar bile duct carcinoma surgically treated between June 1989 and December 1997 at the Asan Medical Center, Seoul, were retrospectively analyzed. Surgical resection was possible in 128 patients. The remaining 23 patients had surgical palliative drainage. Local bile duct excision alone was performed in 17 patients. Liver resection for tumor extending to secondary bile ducts or hepatic parenchyma was performed in 111 patients; portal vein resection was necessary in 29 of these 111 patients (26.1%) and pancreatoduodenectomy was combined in 18 patients (16.2%). Seven patients died during hospitalization after liver resection, an operative mortality of 6.3%. Margins of bile duct resection were free of tumor on histologic examination in 4 of the 17 local bile duct excisions, but in 86 of the 111 liver resections. The cumulative survival rate after local bile duct excision was 85.7% at 1 year, 42.9% at 2 years, 21.4% at 3 years, and 0% at 4 years. However, the survival rate after liver resection (excluding operative mortality) was 97.1% at 1 year, 72.8% at 2 years, 55.3% at 3 years, and 24.0% at 5 years. Survival and the percentage of patients with tumor-free resection margins after liver resection were superior to those after local bile duct excision. Resection of hilar bile duct carcinoma offers long-term survival only when surgery is aggressive and includes liver resection.

Adult↗

A novel microbial interaction: obligate commensalism between a new gram-negative thermophile and a thermophilic Bacillus strain.

Obligately commensal interaction between a new gram-negative thermophile and a thermophilic Bacillus strain was investigated. From compost samples, a mixed culture showing tyrosine phenol-lyase activity was enriched at 60 degrees C. The mixed culture consisted of a thermophilic gram-negative strain, SC-1, and a gram-positive spore-forming strain, SK-1. In mixed cultures, strain SC-1 started to grow only when strain SK-1 entered the stationary phase. Although strain SC-1 showed tyrosine phenol lyase activity, we could not isolate a colony with any nutrient medium. For the isolation and cultivation of strain SC-1, we added culture supernatant and cell extract of the mixed culture to the basal medium. The supernatant and cell extract of the mixed culture contained heat-stable and heat-labile factors, respectively, that are essential to the growth of strain SC-1. During pure cultures of strain SK-1, the heat-stable growth factors were released during the growth phase and the heat-labile growth factors were produced intracellularly at the early stationary phase. Strain SC-1 was gram-negative and microaerophilic, and grows optimally at 60 degrees C. Based on these results, we propose a novel commensal interaction between a new gram-negative thermophile, strain SC-1, and Bacillus sp. strain SK-1.

Bacillus↗

Insecticidal and fumigant activities of Cinnamomum cassia bark-derived materials against Mechoris ursulus (Coleoptera: attelabidae).

The insecticidal and fumigant activities of Cinnamomum cassia (Blume) bark-derived materials against the oak nut weevil (Mechoris ursulus Roelofs) were examined using filter paper diffusion and fumigation methods and compared to those of the commercially available Cinnamomum bark-derived compounds (eugenol, salicylaldehyde, trans-cinnamic acid, and cinnamyl alcohol). The biologically active constituent of the Cinnamomum bark was characterized as trans-cinnamaldehyde by spectroscopic analysis. In a test with the filter paper diffusion method, trans-cinnamaldehyde showed 100 and 83.3% mortality at rates of 2.5 and 1.0 mg/filter paper, respectively. At 2.5 mg/paper, strong insecticidal activity was produced from eugenol (90.0% mortality) and salicylaldehyde (88. 9%), whereas trans-cinnamic acid revealed moderate activity (73.3%). At 5 mg/paper, weak insecticidal activity (50.0%) was produced from cinnamyl alcohol. In a fumigation test, the Cinnamomum bark-derived compounds were much more effective against M. ursulus larvae in closed cups than in open ones. These results indicate that the insecticidal activity of test compounds was attributable to fumigant action, although there is also significant contact toxicity. As a naturally occurring insect-control agent, the Cinnamomum bark-derived materials described could be useful as a new preventive agent against damage caused by M. ursulus.

Aldehydes↗

Cordycepin: selective growth inhibitor derived from liquid culture of Cordyceps militaris against Clostridium spp.

The growth responses of nine human intestinal bacteria to liquid culture of Cordyceps militaris Link. Pt. (Ascomycotina: Clavicipitaceae) collected from a pupa of Bombyx mori L. (Lepidoptera: Bombycidae) were examined using spectrophotometric and impregnated paper disk methods and compared to those of tetracycline and chloramphenicol, as well as those of Coptis japonica root-derived berberine chloride. The biologically active constituent of the cultures was characterized as cordycepin (3'-deoxyadenosine) by spectroscopic analysis. This compound revealed potent growth-inhibiting activity toward Clostridium paraputrificum and Clostridium perfringens at 10 microgram/disk without adverse effects on the growth of Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium longum, Bifidobacterium adolescentis, Lactobacillus acidophilus, and Lactobacillus casei, whereas tetracycline and chloramphenicol inhibited the growth of these lactic acid-producing bacteria, clostridia and Escherichia coli. However, C. militaris-derived materials revealed no growth stimulation on the bifidobacteria and lactobacilli. These results may be an indication of at least one of the pharmacological actions of C. militaris. As a naturally occurring antibacterial agent, cordycepin could be useful as a new preventive agent against various diseases caused by clostridia.

Animals↗

Enhancement of adenoviral transduction with polycationic liposomes in vivo.

Although the high transfection efficiency with adenovirus in vitro is well documented, it is still not clear whether adenoviral vectors are effective in vivo in solid tumor models. In our preliminary experiment, transduction of tumor tissue was limited to just around the injection site after intratumoral injection of the adenoviral vector. To improve the transduction efficiency in vivo, we tried a combination of adenoviral vector and liposome in our animal model. Adenovirus carrying human placental alkaline phosphatase (AdALP) and Lipofectamine or 1,3-di-oleoyloxy-2-(6-carboxyspermyl)-propylamide were used as a marker gene and the cationic liposome, respectively. A >15-fold increase in the transfection efficiency was observed in CT26 tumor cell lines with the combination of AdALP adenovirus carrying murine granulocyte-macrophage colony-stimulating factor (AdmGM-CSF), and liposome compared with adenovirus alone, showing the feasibility of the combination treatment. In the animal model, with the combination of liposome and AdALP, deeper and wider distribution of the marker gene in the tumor mass was shown. We conclude that the limitations of direct application of adenoviral vectors in a solid tumor model could be overcome by the use of cationic liposomes. This approach will facilitate the more effective delivery of adenoviral vectors in a clinical trial setting.

Adenocarcinoma↗

The application of an anti-angiogenic gene (thrombospondin-1) in the treatment of human prostate cancer xenografts.

Angiogenesis is a critical event for solid tumor growth and metastasis. Within a given microenvironment, the angiogenic response is determined in part by the balance between angiogenesis inducers and inhibitors. The aim of this study was to establish a thrombospondin-1 (TSP-1) ( an antiangiogenic gene) expression vector, and to determine the feasibility for use of TSP-1 in prostate cancer gene therapy. The results of this study showed that pCR-TSP-1, the cloned TSP-1 expression plasmid vector, expressed the TSP-1 gene efficiently in DU145, a human prostate cancer cell line. pCR -TSP-1 did not exert any significant growth inhibitory activity on the tested cell line in vitro. However, TSP-1 overexpression inhibited the growth of DU-145 xenografts in Balb/c nude mice when directly transfected with pCR-TSP-1 in combination with a liposomal agent (DOSPER). Histological analysis showed that there were extensive areas of necrosis in the TSP-1 overexpressing tumors, whereas no necrotic foci were observed in the control tumors. Furthermore, the microvessel density was lower in the TSP-1 overexpressing tumors compared to the control tumors. These results suggest that TSP-1 may be a potentially useful gene for prostate cancer gene therapy.

Animals↗

Subcellular localization of presenilins during mouse preimplantation development.

The genes defective in familial Alzheimer's disease encode the proteins presenilin 1 and 2 (PS1 and 2). Expression of presenilins (PSs) and their proteolytic processing are regulated during neuronal development. Even though these proteins are detected and regulated mainly in Golgi and endoplasmic reticulum, their subcellular distribution during the development is not known. The present study aimed to investigate the localization of PSs and their role during early developmental stage using mouse embryo model. At preimplantation stage, PSs were detected not only in cytoplasm, but also in the nucleus from oocyte to 2.5 dpc (day postcoitum), then disappeared in the nucleus at blastocyst stage (3.5 dpc). Antisense against PS1 and PS2 decreased the transition to blastocyst stage, whereas each antisense alone had no effect. Treatment with lactacystin (26S proteosome inhibitor), which arrest cell cycle at M phase, redistributed PSs into centrosome-kinetochore microtubule. PS2 overexpression in HEK 293 cell arrested cell cycle at S phase. These data suggest that PSs play key roles in cell division and differentiation during early development.

Acetylcysteine↗

Results of photodynamic therapy for ablation of dysplasia and early cancer in Barrett's esophagus and effect of oral steroids on stricture formation.

OBJECTIVE: The primary goal of this study was to investigate whether oral steroids would reduce the incidence of stricture formation after photodynamic therapy (PDT) in Barrett's patients. The effect of balloon window length, pretreatment of nodules, retreatment of skipped areas, and subsequent PDT on the incidence of strictures was also investigated. The ultimate goal of treatment was elimination of dysplasia, early cancer, and Barrett's mucosa. METHODS: A total of 60 patients were injected with Photofrin (2 mg/kg). Patients were randomized to receive PDT (n = 30) or PDT and oral prednisone (n = 30). Two days later, 630 nm light (KTP/dye laser) was delivered using a 5- or 7-cm windowed balloon at a light dose of 200 or 175 J/cm. The majority of patients received 200 J/cm using a 7-cm balloon. Nodules were pretreated with a short diffuser at a dose of 50-75 J/cm. Additional light was delivered to skipped areas 2-3 days later. Endoscopies were conducted every 3-6 months to evaluate the response. Residual or recurrent Barrett's was treated using neodymium:aluminum-yttrium-garnet (Nd:YAG) laser (small areas) or was retreated with PDT. RESULTS: The effect of steroids on the incidence of strictures was analyzed in patients receiving a single treatment with a light dose of 200 J/cm using a 7- cm balloon. There was no reduction in the incidence of strictures in patients receiving PDT and steroids (29%) compared to those receiving PDT alone (16%). Treatment using a 7-cm balloon caused more strictures (31%) than treatments using a 5-cm balloon (7%). Pretreatment of nodules or retreatment of skipped areas did not increase strictures. Patients receiving subsequent PDT had a higher incidence of strictures. Cancer was eliminated in all patients. High-grade dysplasia was eliminated in 41 of 43 patients (96%). Barrett's mucosa was totally eliminated in 25 of 60 patients (42%). CONCLUSIONS: Oral prednisone after PDT did not reduce the incidence of strictures. Subsequent PDT and longer balloon window were associated with higher incidence of strictures. PDT followed by thermal ablation of small islands eliminated dysplasia, early cancer, and Barrett's mucosa.

Administration, Oral↗

Antifeeding activity of isoquinoline alkaloids identified in Coptis japonica roots against Hyphantria cunea (Lepidoptera: Arctiidae) and Agelastica coerulea (Coleoptera: Galerucinae).

The anti-feeding activity of 3 isoquinoline alkaloids identified from roots of Coptis japonica Makino toward 4th-instar larvae of Hyphantria cunea Drury and adults of Agelastica coerulea Baly was examined using the leaf-dipping bioassay. The biologically active constituents of the Coptis roots were characterized as the isoquinoline alkaloids berberine, palmatine and coptisine by spectroscopic analysis. In a test with H. cunea larvae, the anti-feeding activity was much more pronounced in an application of a mixture of palmatine iodide and berberine chloride (1:1, wt:wt) at 250 ppm (82.3%) and 500 ppm (100%), compared with palmatine iodide (76.0%) and berberine chloride (75.4%) alone at 500 ppm. These results indicate a synergistic effect. With A. courulea adults, berberine chloride showed 57.5 and 91.1% anti-feeding activity at 125 and 250 ppm, respectively; whereas, weak activity was obtained in application of 500 ppm of palmatine iodide (41.4%) and coptisine chloride (52.4%) alone. The Coptis root-derived compounds merit further study as potential insect-control agents.

Animals↗

Regulatory effect of cytokine production in patients with cerebral infarction by Yulda-Hanso-Tang.

Yulda-Hanso-Tang (YH-Tang) is a prescription for the Taeumin cerebral infarction (CI) patients according to Sasang constitution philosophy. Taeumin patients with CI were treated with YH-Tang during the acute stage. Clinical signs of CI disappeared markedly in about 2 weeks after oral administration of YH-Tang in all patients. The mean interleukin (IL)-2 serum levels were lower in the patients with CI than in the normal groups, whereas the mean IL-4, IL-6 and IgE levels were significantly higher in the patients. There were no significant differences in interferon-gamma (IFN-gamma) levels between the groups. Serum IFN-gamma and IL-2 levels derived from T helper (Th)1 cells elevated significantly in the patients with CI by YH-Tang administration. Significant reduced serum levels of IL-4 and IL-6 derived from Th2 cells and IgE were observed in the patients treated with YH-Tang. During the period of YH-Tang administration, there were no other adverse effects. The data indicate that YH-Tang has a good CI treatment effect, and that its action may be due to regulation of cytokine production.

Cerebral Infarction↗

A sequence-ready map for human chromosome 12q15-21.

Construction of sequence-ready clone map is an essential step toward sequencing the human genome. We chose a region that is frequently amplified in liposarcoma between D12S350 and D12S106 in chromosome 12q15-21 to build a PAC/BAC clone contig map. This region was spanned by 4 YACs and contained 30 STS on the YAC and radiation hybrid (RH) framework maps, providing an average STS spacing of 160 kb if each YAC is approximately 1.2 Mb in size. To convert a STS-based YAC map to a STS-based contig map of bacterial clones, 22 non-polymorphic STS markers were used as probes to screen the high density gridded arrays of PAC and BAC clones by filter hybridizations, followed by assembly of clones into contigs by marker content. Contigs have been extended and joined by direct end sequencing of appropriate clones, generating new STSs and rescreening the library as necessary. Using these approaches, we have constructed 5 contigs covering the region with the largest single contig being 1.4 Mb and a final size estimation of 3.6 Mb. The map is comprised of 17 YACs, 187 PACs, 160 BACs, and 17 cosmids; onto this, 6 polymorphic, 97 non-polymorphic, 24 ESTs, and 4 gene-based markers are now placed in a unique order, providing an average resolution of approximately 28 kb. Of a total of 131 markers, 97 were developed in the present study. The sequence-ready map should provide a framework to generate complete DNA sequence and ultimately gene map of this segment of chromosome 12.

Base Sequence↗