• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1670-1674
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• 2007

Duffy binding protein (DBP) plays a critical role in Plasmodium vivax invasion of human red blood cells. We previously reported a single-chain antibody fragment (scFv) that was specific to P. vivax DBP (PvDBP). However, the stabilization and the half-life of scFvs have not been studied. Here, we investigated the effect of PEGylated scFvs on their biological activity and stability in vitro. SDS-PAGE analysis showed that three clones (SFDBII-12, -58, and -92) were formed as monomers (about 70 kDa) with PEGylation. Clone SFDBII-58 gave the highest yield of PEGylated scFv. Binding analysis using BIAcore between DBP and scFv showed that both SFDBII-12 and -58 were decreased approximately by two folds at the level of binding affinity to DBP after PEGylation. However, the SFDBII-92 clone still showed a relatively high level of binding affinity ($K_D=1.02{\times}10^{-7}\;M$). Binding inhibition assay showed that PEGylated scFv was still able to competitively bind the PvDBP and playa critical role in inhibiting the interactions between PvDBP protein expressed on the surface of Cos-7 cells and Duffy receptor on the surface of erythrocytes. When both scFvs and their PEGylated counterparts were exposed to trypsin, scFv was completely degraded only after 24 h, whereas 35% of PEGylated scFvs remained intact, maintaining their stability against the proteolytic attack of trypsin until 72 h. Taken together, these results suggest that the PEGylated scFvs retain their stability against proteolytic enzymes in vivo, with no significant loss in their binding affinity to target antigen, DBP.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.10
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• pp.4197-4201
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• 2014

Minor trauma to the uterine cervix is supposed to induce local immunity to prevent cervical lesions caused by human papillomavirus (HPV) infection. This study aimed to investigate the local cervical immunity in women with low grade squamous intraepithelial lesion (LSIL) and effects of abrasion after cryosurgery or Pap smear. One hundred women with LSIL and known results of HPV detection were recruited. HPV positive women were randomly divided according to abrasion into cryotherapy and Pap smear observation groups. Cervical tissues and cervico-vaginal lavage (CVL) were collected at 6 and 12 months after allocation. The levels of cytokines at first recruitment were compared with cytokine levels at 6 months after abrasions. The mRNA of IFN-${\gamma}$, TNF-${\alpha}$ and IL-10 in cervical tissues and these cytokines secreted in CVL were determined using real time PCR and ELISA, respectively. Anti-HPV16 IgG and IgA antibodies in CVL were assessed by western blotting. At first recruitment of women with LSIL (100 cases), IL-10 mRNA and cytokine in HPV positive group (60 cases) was significantly higher than negative group (40 cases). IFN-${\gamma}$ and TNF-${\alpha}$ mRNA level in both groups were comparable but their secretions in CVL were significantly increased in HPV negative group. After abrasion for 6 months in HPV-positive women, all mRNA and secreted cytokines were changed, but no significant difference was observed between cryotherapy and observation groups. When individuals were compared between first recruitment and after abrasion for 6 months, IFN-${\gamma}$ mRNA and anti-HPV16 L1 IgA antibodies were significantly increased in the cryotherapy group. The results suggest that modulation of local cervical immunities by abrasion might promote different effects in clearance of HPV-related cytological abnormalities.

• Journal of agricultural medicine and community health
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• v.26 no.2
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• pp.181-191
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• 2001

Toxocariasis is produced by the migration of Toxocara canis larvae into the extra- intestinal tissue of unnatural hosts or natural hosts under unsuitable conditions. Soil contaminated with T. canis embryonated eggs in the main source of infection of man. In the present study, ELISA with T. canis adult crude antigen was used for determination the seroprevalence of T. canis infection in two areas of Korea. It was found that antibody positive rate was 15.7% in Keoje- Island. In the analysis according to sex, female group presented significantly higher positive rate than male group (23.8% in female and 7.4% in male, p<0.05). In Inchon city, the positive rate was 13.1%, and there was no significant difference between female and male group. Immunoblot analysis was performed to some positive patient sera. As the results, 9 cases of 15 cases were positive in Keoje-Island, and 22 cases of 27cases were positive in Inchon city by immunoblotting.

• The Journal of Korean Society of Virology
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• v.26 no.1
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• pp.9-22
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• 1996

Respiratory Syncytial virus (RSV) is an important cause of acute lower respiratory tract infections in human, with infants and young children being particularly susceptible. In the temperate zones, sharp annual outbreaks of RSV occur during the colder months, in both the northern and the southern hemisphere. RSV is unusual in that it can repeatedly reinfect individuals throughout life and infect babies in the presence of maternal antibody. RSV isolates can be divided into two subgroups, A and B, on the basis of their reactions with monoclonal antibodies, and the two subgroups are also distinct at the nucleotide sequence level. The specific diagnosis of RSV infection was best made by isolation of virus in tissue culture, identification of viral antigen, or by specific serologic procedures. Recently, rapid detection of RSV and analysis of RSV strain variation became possible by development of methods of reverse transcription and polymerase chain reaction amplification. In this study, to determine the genetic diversity of RSV found in Korea, 173 bp and 164 bp spanning selected regions of the RSV F and SH genes were enzymatically amplified and sequenced, respectively. Eight for F gene and three for SH gene were detected in 66 nasopharyngeal swap samples tested. Two major antigenic subgroups, A and B were confirmed from Korean samples (seven for subgroup A and one for subgroup B). At the nucleotide level of the F gene region, Korean subgroup A strains showed 95-99% homologies compared to the prototype A2 strain of subgroup A and 93-100% homologies among Korean subgroup A themselves. For the SH gene region, Korean subgroup A strain showed 97.5% homology compared to the prototype A2 strain of subgroup A, and Korean subgroup B strain showed 97% homology compared to the prototype 18537 strain of subgroup B. Most of base changes were transition and occured in codon position 3, which resulted in amino acid conservation. Using the maximum parsimony method, phylogenetic analysis indicated that Korean RSV strains formed a group with other RSV strains isolated from the United States, Canada, the Great Britain and Australia.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.3
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• pp.437-443
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• 2003

Epidemiological data suggest that lycopene has anticancer activities in humans. Insulin-like growth factor-I receptor (IGF-IR) is a transmembrane tyrosine kinase that mediates the biological actions of IGFs and may play an active role in cancer progression. Because our previous in vitro studies have indicated lycopene inhibits HT-29 cell growth, the aim of this study was to determine whether lycopene induces apoptotic cell death and the inhibitory effect of lycopene on HT-29 cell growth is related to changes in IGF-IR levels and the receptor's intracellular signalling pathways. HT-29 cells were incubated for 4 days in serum-free medium in the presence of 0, 25, 50, or 100 $\mu$M lycopene, and the DNA fragmentation assay was performed. Cells treated with lycopene produced a distinct oligonucleosomal ladder with different sizes of DNA fragments, a typical characteristic of cells undergoing apoptosis. HT-29 cells were cultured for 4 days in serum-free medium in the presence of 0~100 $\mu$M lycopene and IGF-I (10nM) was added for 0~60 minutes immediately prior to lysate preparations. Western blot analysis of total lysates revealed that lycopene decreased the levels of IRS-1, Akt, phosphatidylinositol 3-kinase (PI3K), and IGF-IR $\beta$-subunit, and increased the levels of the IGF-IR precursor dose dependently. Lycopene also decreased IGF-I-induced phosphorylation of IGF-IR$\beta$, IRS-1 and Akt, which were, at least in part, due to decreased expression of these proteins. These results suggest that lycopene induces apoptosis of HT-29 cells by inhibiting IGF-IR signaling thereby interfering with an IGF-II-driven autocrine growth loop, which is known to exist in this cell line.

• The Journal of Korean Society of Virology
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• v.28 no.3
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• pp.247-265
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• 1998

To determine the sequence and expression of the VP7 gene of Korean isolates (CAU-9), viral RNA was purified and used for cDNA amplification by RT-PCR. The VP7 cDNA was cloned, sequenced, and expressed using baculovirus expression system. The result showed that the sequence homologies CAU-9 compared with foreign isolated strains Wa, 417, TMC-II, 95B and SA11 were ranged from 74.0% to 95.1 % of nucleotide sequence and 35% to 43% of amino acid sequence, respectively. High homology of CAU-9 was observed in Japanease isolates 417 (nucleotide sequence homology was 95.1% and amino acid sequence homology was 43%). To express VP7 gene, the VP7 cDNA was cloned into pCR-Bac vector and inserted into the genome of baculovirus adjacent to the polyhedrin promoter by cotransfection of Spodoptera frugiperda (Sf9) insect cells with wild type baculovirus DNA. In antigenic analysis of Sf9 cells inoculated with the recombinant VP7, immunofluorescence assay revealed positive for viral antigens. In metabolic labeling of Sf9 cell lysates infected with recombinant baculoviruses, it was revealed that the protein of 34 kDa was expressed. The limited study of expressed VP7 protein inoculated with guinea pigs failed to elicit neutalizing antibody. As a results, the sequence analysis and expression of VP7 protein of rotavirus CAU-9 isolated from an infant in Korea could permit the conformation and development of virus like particles which may be useful in designing vaccine strategy.

• Parasites, Hosts and Diseases
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• v.31 no.2
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• pp.149-156
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• 1993

Monoclonal antibodies (Mabs) were produced against crude scolex extract of T solium metacestodes, and applied to ELISA-inhibition test for improving the specificity of serodiagnosis of human cysticercosis. Four hybridomas secreting species-specific anti- cysticercal Mabs (Cya-1, Cya-7, Cya-28 and Cya-31) were selected. Each Mab reacted on antigenic components of 25.5 kDa (Cya-1), 28 kDa (rcya-7), 87.5 kDa (Cya-281), and 12.5 kDa (Cya-31). IFA showed that Cya-1 was located at the calcium corpuscles, and Cya-7 at the loose connective tissue of T soLium metacestode scolex. Cya-28 and Cya-31 reacted on the tegument of the scolex. By conventional ELISA, 23 out of 28 (82.1%) cysticercosis patients were found serologically positive, but 1 out of 9 (11.1%) sparganosls cases and 6 out of 31 (19.4%) paragonlmiasis cases showed false positives. By ELISA-Inhibition test using species-specific anti-cysticercal Mab Cya-7, 19 out of 28 (67.9%) cystlcercosis cases were found serologically positive, but there were no false positives In other parasitic infections.

• Parasites, Hosts and Diseases
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• v.50 no.4
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• pp.287-293
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• 2012

Knowledge of the prevalence of human Toxoplasma gondii infection is required in the Republic of Korea. In this study, we surveyed the seroprevalence of T. gondii infection and analyzed the risk factors associated with seropositivity among residents in 2 administrative districts; Seoul and the island of Jeju-do, which have contrasting epidemiologic characteristics. Sera and blood collected from 2,150 residents (1,114 in Seoul and 1,036 in Jeju-do) were checked for IgG antibody titers using ELISA and for the T. gondii B1 gene using PCR. In addition, participants completed a questionnaire that solicited information on gender, age, occupation, eating habits, history of contact with animals, and travel abroad. The T. gondii B1 gene was not detected in all residents examined. However, ELISA showed 8.0% (89 of 1,114 sera) positive for IgG antibodies against T. gondii in Seoul and 11.3% (117 of 1,036 sera) in Jeju-do. In both districts, the positive rates were higher in males than in females, and those 40-79 years of age showed higher rates than other ages. In Seoul, residents older than 70 years of age showed the highest positive rate, 14.9%, whereas in Jeju-do the highest prevalence, 15.6%, was in those in their sixties. The higher seropositive rate in Jeju-do than in Seoul may be related to eating habits and occupations. The present results and a review of related literature are indicative of an increased seroprevalence of T. gondii in Korea in recent years.

• Journal of Plant Biotechnology
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• v.40 no.3
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• pp.169-177
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• 2013

Recently, the number of people with diabetes is rapidly increasing, coupled with the fact that the insulin market is remarkably increasing. Therefore, molecular farming for plant-derived pharmaceutical protein production is reported as becoming more attractive than ever. In this study, we carried out experiments step by step for development of recombinant insulin constructs, which were transformed into E. coli system, in vitro transcription and translation system, and tobacco cells. At first, recombinant proinsulin protein was successfully produced in in vitro transcription and translation system with wheat germ extract. After which, recombinant construct of prominiinsulin encoded a fusion protein of 7.8 kDa with trypsin cleavage sites at N terminus and C terminus of minimized C-peptide was tried to in vitro expression using E.coli culture. After purification with His-tag column, the resulting recombinant prominiinsulin protein was processed with trypsin, and then checked insulin biosynthesis by SDS-PAGE and western blot analysis with anti-insulin monoclonal antibody. The immunoreactive product of trypsin-treated miniinsulin was identical to the predicted insulin hexamer. The construct of 35S promoter-driven preprominiinsulin recombinant gene with signal peptide region for ER-targeting and red fluorescence protein gene [N terminus ${\rightarrow}$ tobacco E2 signal peptide ${\rightarrow}$ B-peptide (1-29 AA) ${\rightarrow}$ AAK ${\rightarrow}$ A-peptide (1-21 AA) ${\rightarrow}$ RR ${\rightarrow}$ His6 ${\rightarrow}$ KDEL ${\rightarrow}$ C terminus] was transformed into BY-2 tobacco cells. A polypeptide corresponding to the 38-kDa molecular mass predicted for fusion protein was detected in total protein profiles from transgenic BY-2 cells by western analysis. Therefore, this recombinant preprominiinsulin construct can be used for generation of transgenic tobacco plants producing therapeutic recombinant insulin.

• Korean Journal of Veterinary Pathology
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• v.2 no.2
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• pp.95-106
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• 1998

The prevalence of primary liver carcinoma (PLC) is relatively high in Clonorchis sinensis (CS) endemic areas in Korea. PLC is a malignant tumor which can be subclassified into hepatocellular carcinoma and cholangiocarcinoma(CC). CC has been associated with clonorchiasis, but it is unclear whether clonorchiasis is associated with hepatocarcinogenesis. This experiment was designed to investigate relationships between clonorchiasis and early changes of hepatocarcinogenesis. Sixteen Sprague-Dawley rats weighing 150g were divided into two groups of 8 rats in each. All rats were fed choline-devoid(CD) diet for 4 weeks. Group 1 was given 0.015-0.020% diethylnitrosamine(DEN) as drinking water for 1 week. After one week, the rats were treated orally with 1% N-acetylaminofluorene(AAF) (5 times per week for 2 weeks). Group 2 was treated equally to group 1 except for CS infection during AAF treatment. Two rats in each group were sacrificed at 4th, 5th, 6th and 7th week of the experiment. Livers were stained with OV -6, proliferating cell nuclear antigen(PCNA) and GST-p. Results were as follows: Group 2 livers showed more oval cell proliferation in parenchyma and portal areas at the 4th, 5th, 6th and 7th weeks than did livers of group 1 (p＜0.01). PCNA was mostly localized in oval cell populations, rather than hepatocytes and biliary cells. The ratio of oval cells to hepatocytes was much higher in group 2 than in group l(p＜0.01 The ratio of hepatocytes to biliary cells is higher in group 2 than in group 1 (p＜0.05), More group 2 acidophilic foci reacted to GST-p monoclonal antibody than in the noninfected group. It appeared that CS infection promoted potentially precancerous acidophilic foci and oval cell proliferation.