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        검색결과 533

        201.
        2012.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate the effects of redox reaction on preparation of high purity α-alumina from selectively ground aluminum dross. Preparation procedure of the α-alumina from the aluminum dross has four steps: i) selective crushing and grinding, ii) leaching process, iii) redox reaction, and iv) precipitation reaction under controlled pH. Aluminum dross supplied from a smelter was ground to separate metallic aluminum. After the separation, the recovered particles were treated with hydrochloric acid(HCl) to leach aluminum as aluminum chloride solution. Then, the aluminum chloride solution was applied to a redox reaction with hydrogen peroxide(H2O2). The pH value of the solution was controlled by addition of ammonia to obtain aluminum hydroxide and to remove other impurities. Then, the obtained aluminum hydroxide was dried at 60˚C and heat-treated at 1300˚C to form α-alumina. Aluminum dross was found to contain a complex mixture of aluminum metal, aluminum oxide, aluminum nitride, and spinel compounds. Regardless of introduction of the redox reaction, both of the sintered products are composed mainly of α-alumina. There were fewer impurities in the solution subject to the redox reaction than there were in the solution that was not subject to the redox reaction. The impurities were precipitated by pH control with ammonia solution, and then removed. We can obtain aluminum hydroxide with high purity through control of pH after the redox reaction. Thus, pH control brings a synthesis of α-alumina with fewer impurities after the redox reaction. Consequently, high purity α-alumina from aluminum dross can be fabricated through the process by redox reaction.
        4,000원
        202.
        2012.06 구독 인증기관 무료, 개인회원 유료
        We prepared the polyclonal antibody anti-20α-hydroxysteroid dehydrogenase (anti-20α-HSD) against the recombinant full-length protein bovine 20α-HSD in Escherichia coli. The specificity of anti-20α-HSD was demonstrated using Chinese hamster ovary (CHO) cells transfected with recombinant bovine 20α-HSD and bovine placental tissues. According to western blot analysis, anti-20α-HSD specifically recognizes the 37-kDa protein bovine 20α-HSD. The protein is not present in untransfected CHO cells. Anti-20α-HSD also recognizes a specific protein in the ovaries and placenta of other animals. Immunostaining was used to detect expression of bovine 20α-HSD protein in the cultured luteal cells during the estrous cycle later.
        4,000원
        203.
        2012.06 구독 인증기관·개인회원 무료
        In this study, we examined whether Hanganutziu‐Deicher (H‐D) antigens are important as an immunogenic non‐a1,3‐galactose (Gal) epitope in pigs with a disrupted a1,3‐ galactosyltransferase gene. The targeting efficiency of the AO blood genotype was achieved (2.2%) in pig fibroblast cells. A total of 1800 somatic cell nuclear transfer (SCNT) embryos were transferred to 10 recipients. One recipient developed to term and naturally delivered two piglets. The a1,3‐galactosyltransferase activity in lung, liver, spleen, and testis of heterozygote a1,3‐galactosyltransferase gene knockout (GalT‐KO) pigs was significantly decreased, whereas brain and heart showed very low decreasing levels of a1,3‐ galactosyltransferase activity when compared to those of control. Enzyme‐linked lectinosorbent assay showed that the heterozygote GalT‐KO pig had more sialyla2,6‐ and sialyla2,3‐ linked glycan than the control. Furthermore, the heart, liver, and kidney of the heterozygote GalT‐KO pig had a higher N‐glycolylneuraminic acid (Neu5Gc) content than the control, whereas the lung of the heterozygote GalT‐KO pig had Neu5Gc content similar to the control. Collectively, the data strongly indicated that Neu5Gc is a more critical xenoantigen to overcoming the next acute immune rejection in pig to human xenotransplantation.
        204.
        2012.06 구독 인증기관·개인회원 무료
        동물의 장기를 인간에게 이식하게 되면 초급성거부반응(Hyperacute rejection, HAR)이 일 어난다. 초급성거부반응은 면역계의 구성요소 중 보체(complement)에 의해 일어나는 거부 반응으로 돼지의 혈관세포 표면에 있는 Galα(1,3)Gal 당분자에 인간의 항체가 즉각 반응하 기 때문에 일어나며, α1,3-galactosyltransferase(α1,3-GT) 유전자는 돼지 혈관세포 표면의 Galα(1,3)Gal 당분자 생성에 관여한다. 따라서 인간에게 돼지의 장기를 이식하기 위해서는 α1,3-galactosyltransferase 유전자를 제거하는 것이 필요한 것으로 알려져 있다. 본 연구 실 의 이전 연구에서, 시카고 미니돼지 귀체세포에서 상동 재조합(Homologous recombination) 을 통해 α1,3-galactosyltransferase 유전자가 제거된 체세포를 개발한 바 있으며, 이 체세 포 를 통하여 α1,3-GT 유전자가 제거된 돼지도 생산된 바 있다. 본 연구에서는, Human serum 처리 시 돼지 세포를 보호해준다고 보고되고 있는 human complement regulator인 human Decay-accelerating factor(hDAF)와 human α1,2-fucosyltransferase(hHT) 유전자를 α1,3 -GT 유전자 위치에 gene targeting하여 동시에 hDAF와 hHT가 발현하는 체세포를 개발하였다. Knock-in vector는 hDAF와 hHT 두 유전자가 발현할 수 있도록 IRES로 연결하였으며 α 1,3-GT 유전자의 start codon을 이용하여 발현할 수 있도록 구축하였다. 구축한 vector는 electroporation을 통해 미니돼지 체세포에 도입하였으며, PCR 결과 α1,3-GT 유전자 위치 에 서 상동 재조합이 일어났음을 확인하였다. Positive-negative 선별 방법을 통해 얻은 gene targeting된 체세포는 RT-PCR에 의해 hDAF와 hHT 유전자의 발현이 확인되었으며, 대조군 (NIH minipig)에 비해 α1,3-GT 유전자의 발현이 감소하였다. 또한, 이들 세포에 100% human complement serum을 처리하였을 때 Knock-in 세포가 대조군에 비해 30% 정도 더 높 은 생존율을 보였다. 따라서 개발된 체세포는 이종간 장기이식을 위한 돼지 생산과 함께 이를 이용한 이종간의 장기 이식 시 초급성 거부반응을 억제하는 데 사용 될 수 있을 것으로 생각된다.
        205.
        2012.06 구독 인증기관·개인회원 무료
        20ɑ-hydroxysteroid dehydrogenase (20ɑ-HSD) enzyme converts progesterone into biological inactive steroid, thus playing a key role in the termination of pregnancy or estrus cycle and allowing parturition and ovulation to occur in most mammalian animals. However, function and regulation of this enzyme has not known well in primate reproductive physiology. We previously demonstrated the expression level and localization of the 20α-HSD in the reproductive tissues of macaque monkeys of pre-ovulation and pre-parturition period. Also, we amplified about 2005 bp 5'-flanking region from placenta genomic DNA and examined methylation pattern and promoter activity. In present study, we focus on the analysis of molecular characterization of the promoter region by using reporter assay systems. We constructed of deleted mutants (— 890 bp; HSF-2), (— 513 bp; XFD), (— 276 bp; Ap-1) and (— 72 bp; Sp-1) and each mutants were cloned into pGL3-basic vector. These deletion mutants were transfected into CHO cells and co-transfected with Sp-1 or Ap-1 transcription factor plasmids. Compared to — 890 bp and 513 bp promoter fragments alone, transcription activity increased when these constructs were co-transfected with Sp-1 and Ap-1 factor. However, for the absence Ap-1 factor binding site in 276 bp fragment activity dramatically decreased in both transfections. Next, we constructed of 306 bp fragment which is including of Ap-1 binding site and nucleotides converted mutants of the Ap-1 factor binding site. In this result, 306 bp fragment's transcription activity was high as wild type. However, the mutant activity which converted Ap-1 site’s all nucleotide was significantly decreased. These findings are confirmed by gel-shift assay examining Ap-1 binding site on the 20 α-HSD gene upstream region and expression of Ap-1 factor was determined by RT-PCR and Western blot in pre-parturition period placenta and CHO-K1 cell line. Our results indicate that Ap-1 site (— 281 → — 274) (5'-TGTCTCAT-3') plays a crucial role for monkey 20 α- HSD gene transcription.
        206.
        2012.05 구독 인증기관·개인회원 무료
        An endoparasitoid wasp, Cotesia plutellae parasitized young larvae of diamondback moth, Plutella xylostella. Parasitized larvae exhibit sign ificant immunosuppression and fail to metamorphose to pupal stage. Especially, during last instar of parasitized P.xylostella, massive nutrients divert from host to wasp development. CpBV15α ,a host translation inhibitory factors encoded in C. Plutella bracovirus(CpBV), plays a crucial role in suppressing host usage of amino acids. Its promoter analysis shows that CpBV15α specifically inhibit host development in late larval period. To understand its inhibitory target, its specific expression was performed in non-parasitized P. xylostella by in vivo transient expression technique. Total plasma proteins were analyzed by 2D gel electrophoresis and determined target genes inhibited by CpBV15α. Immunoprecipation of cellular extract with CpBV15α antibody captured eIF2B. CpBV15α shares sequence homology with eIF5, especially at its eIF2B-binding region. Our results suggest that CpBV15α may sequester eIF2B, which result in malfunctioning of eIF2 cycling to form a translation initiation complex.
        209.
        2011.12 구독 인증기관 무료, 개인회원 유료
        Tumor necrosis factor alpha (TNFα) is a multifunctional cytokine that is elevated in inflammatory diseases such as atherosclerosis, diabetes and rheumatoid arthritis. Recent evidence has suggested that β2 adrenergic receptor(β2AR) activation in osteoblasts suppresses osteogenic activity. In the present study, we explored whether TNFα modulates βAR expression in osteoblastic cells and whether this regulation is associated with the inhibition of osteoblast differentiation by TNFα. In the experiments, we used C2C12 cells, MC3T3- E1 cells and primary cultured mouse bone marrow stromal cells. Among the three subtypes of βAR, β2 and β3AR were found in our analysis to be upregulated by TNFα. Moreover, isoproterenol-induced cAMP production was observed to be significantly enhanced in TNFα-primed C2C12 cells, indicating that TNFα enhances β2AR signaling in osteoblasts. TNFα was further found in C2C12 cells to suppress bone morphogenetic protein 2-induced alkaline phosphatase (ALP) activity and the expression of osteogenic marker genes including Runx2, ALP and osteocalcin. Propranolol, a β2AR antagonist, attenuated this TNFα suppression of osteogenic differentiation. TNFα increased the expression of receptor activator of NF-κB ligand (RANKL), an essential osteoclastogenic factor, in C2C12 cells which was again blocked by propranolol. In summary, our data show that TNFα increases β2AR expression in osteoblasts and that a blockade of β2AR attenuates the suppression of osteogenic differentiation and stimulation of RANKL expression by TNFα. These findings imply that a crosstalk between TNFα and β2AR signaling pathways might occur in osteoblasts to modulate their function.
        4,000원
        210.
        2011.10 구독 인증기관·개인회원 무료
        Prostaglandins (PGs) are critical lipid mediators involved in many reproductive processes including luteolysis, maternal recognition of pregnancy, and implantation in domestic animals. In pigs, PGs, especially PGE2 and PGF2α, are produced in the uterine endometrium. The actions of PGE2 and PGF2α are mediated by signaling receptors, PTGERs and PTGFR, respectively, but their expression in the uterine endometrium is not well elucidated. In this study, we determined expression of PTGERs and PTGFR in the uterine endometrium during the estrous cycle and pregnancy in pigs. Uterine endometrial tissue samples were collected from Day (D) 12 and D15 of the estrous cycle and from D12, D15, D30, D60, D90, and D114 of pregnancy. Temporal expression of all genes studied was analyzed by real-time RT-PCR. PTGERs except for PTGER1 were expressed in the uterine endometrium during the estrous cycle and pregnancy. Levels of PTGER2 and PTGER3 mRNA increased during early pregnancy and late pregnancy, respectively, and levels of PTGER4 mRNA were not changed during pregnancy. Levels of PTGFR mRNA were highest on D90 of pregnancy. Results of this study showed that expression of PG receptors was dynamically regulated in the uterine endometrium during pregnancy in pigs. These results indicate that actions of PGs are dependent on types of receptors and is critical to support the establishment and maintenance of pregnancy at the maternal-fetal interface in pigs.
        211.
        2011.10 구독 인증기관·개인회원 무료
        Immunological rejection of the organ grafted onto a primate arises from two antibody mediated processes, hyperacute rejection (HAR) and acute humoral rejection (AHR). Functional ablation of α1,3-galactosyltransferase (GalT) and concurrently overexpression of complement regulatory proteins are known to inhibit HAR and AHR. In previous study, we reported that production of porcine male fibroblasts harboring a MCP expression cassette targeted to GalT locus. In this study, we constructed a different MCP expression cassette, in which the EF1α promoter regulates MCP expression and internal ribosome entry site-mediated neomycin resistance gene expression. Subsequently, this cassette was inserted between the left and the right homologous arms to target exon 9 of the GalT gene. Female fibroblasts were isolated from ear skin of 10 days old miniature pig, and used for nucelofection of the the construct for MCP expression at GalT locus. PCR analysis showed that four clones of forty neomycin resistant clones carry MCP expression cassette at exon 9 of the GalT gene. Two clones analyzed downregulated GalT expression, as determined by quantitative reverse transcriptase polymerase chain reaction. Flow cytometry analysis showed that MCP was efficiently expressed at the cell surface.
        212.
        2011.10 구독 인증기관·개인회원 무료
        The phylogenetic relationships among the Nymphalidae (Lepidoptera: Papilionoidea) have been controversial in several perspective. The present study sequenced a total of ~ 3,500 bp from cytochrome oxidase subunit I (COI), 16S ribosomal RNA (16S rRNA), and elongation factor-1 alpha (EF-1α) in 80 nymphalid species belonging to seven subfamilies (Linmenitidinae, Heliconiinae, Nymphalinae, Apaturinae, Libytheinae, Satyrinae, and Danainae), along with those of six lycaenid species as outgroups. Phylogenetic analyses via Bayesian Inference (BI) and Maximum Likelihood (ML) algorithms concordantly supported the subfamilial relationships of (((((Linmenitidinae + Heliconiinae) + (Nymphalinae + Apaturinae)) + Libytheinae) + Satyrinae) + Danainae), with high nodal support for monophyletic subfamilies and tribes. This result is largely consistent with a previous study performed with a substantially large sequence information and morphological characters, except for the position of Libytheinae that has previously been placed as the sister to all reminder of Nymphalidae.
        213.
        2011.09 구독 인증기관 무료, 개인회원 유료
        The aim of this study was to evaluate the effect of α-tocopherol on blastocysts development and subsequent cryosurvival of the vitrification. The α-tocopherol(0, 100, 200, 400 μM) was added in to culture medium for the bovine embryos. The blasocysts from the α-tocopherol and untreated control groups were then frozen-thawed, and their cryosurvival was assessed by in vitro culture for 48 h. There were no differences in the overall cleavage rate(56.14±4.66, 58.18±4.70, 62.97±6.86 and 51.17±7.28) among four treatment groups. However, in blastocyst development and total cell number were significantly higher in α-tocopherol 200 μM(38.60±7.12; 106.33±3.50) to culture medium than other treatment groups(29.30±5.24, 31.60±7.12 and 26.37±4.18; 101.36±5.12, 97.27±2.87, and 91.23±7.52 respectively). Before and after vitrification, the total cell number and blastocyst development of embryo were significantly higher in July to August than September to October. In conclusion, addition of α-tocopherol 200 μM to in vitro bovine embryo culture medium was beneficial for improving embryo quality by decreasing the embryo damage blsstocysts cell number and improving the tolerance of the embryos to cryopreservation.
        4,000원
        214.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cancer cells are often found in an ischemic condition due to the rapid outgrowth of their vascular supply, and these cells are expected to develop an increased potential for local invasive growth. Since the first steps are characterized by increased motility and invasiveness, expression of molecules involved in cellular adhesion to extracellular matrix (ECM) is increased in the process of cancer cell invasion and metastasis. In this work we explored the molecular characteristics and its regulatory mechanism of hypoxic oral squamous cell carcinoma (OSCC) cells. Our experiment identified that hypoxia increases α5 integrin protein levels through phosphoinositide 3-kinase (PI3K)/Akt pathway in OSCC cells.
        4,000원
        216.
        2011.05 구독 인증기관·개인회원 무료
        The phylogenetic relationships among the Nymphalidae (Lepidoptera: Papilionoidea) have been controversial. The present study sequenced approximately 1,099 bp from cytochrome oxidase subunit I (COI), 1,336 ~ 1,551 bp from 16S ribosomal RNA (16S rRNA), and 1,066 bp from elongation factor-1 alpha (EF-1α) in 80 species belonging to seven subfamilies (Linmenitidinae, Heliconiinae, Nymphalinae, Apaturinae, Libytheinae, Satyrinae, and Danainae) of Nymphalidae, along with those of six lycaenid species as outgroups. The average base compositions for the three genes (COI, 16S rRNA, and EF-1α) are as follows: A (30.6%, 38.8%, and 25.8%), G (14.7, 5.2%, and 23.6%), T (39.8%, 45.2%, and 23.4%), and C (14.9%, 10.8%, and 27.3%). This result shows the A/T bias in the mitochondrial genes, but not for the nuclear EF-1α. Between the two mitochondrial genes, the 16S rRNA gene evidenced a significantly higher A/T content than was detected in the COI gene. These sequences were subjected to phylogenetic reconstruction via Bayesian Inference (BI) and Maximum Likelihood (ML) algorithms. Both analyses concordantly supported the subfamilial relationships of (((((Linmenitidinae + Heliconiinae) + (Nymphalinae + Apaturinae)) + Libytheinae) + Satyrinae) + Danainae), along with highly supported monophyletics of tribes within subfamilies. This result is largely consistent with a previous study performed with a large sequence information and morphological characters, except for the position of Libytheinae, which was suggested to be the basal lineage of Nymphalidae.
        219.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Tomato fruits(Lycoperisicon esculentum) synthesize the glycoalkaloids dehydrotomatine and α-tomatine, possibly as defense against bacteria, fungi and insects. We developed a new effective method to prepare and purify dehydrotomatine and α-tomatine that exists in tomato fruits using alumina column chromatography and high performance liquid chromatography (HPLC). The tomato glycoalkaloids(TGA) in tomato was extracted with 2% acetic acid, and then precipitated with ammonium hydroxide(pH=10.5). The dry precipitate substance was applied on alumina column, and then fractionated with water saturated n-butylalcohol. The TGA(Fr. No. 26~36) were collected and dried under reduced pressure. The TGA was performed on a reverse phase HPLC(Inertsil ODS-2, 5 ㎛), eluted with acetonitrile/20mM KH2PO4(24:76, v/v) at 208 ㎚. Two peaks were detected on HPLC, and individual peak was collected by repeating HPLC. Furthermore, to confirm the identity dehydrotomatine and α-tomatine, each peak isolated was hydrolyzed with 1N HCl into sugar and aglycone tomatidine. The sugars were converted to trimethylsilyl ester derivatives. The nature and molar ratios of sugars were identified by gas-liquid chromatography(GLC) and the aglycone by high-performance liquid chromatography(HPLC). The first peak (Rt=17.5 min) eluted from HPLC was identified as dehydrotomatine, and second peak(Rt=21.0 min) was as α-tomatine. This technique has been used effectively to prepare and isolate dehydrotomatine and α-tomatine from tomato fruits.
        4,000원
        220.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The possibility of commercializing the controlled release of chitosan carrier nano formulation was examined with mortalities and population increase rates of Aphis gossypii and Myzus persicae after treatment of 2 α-cypermethrin nano type formulations of different chitosan carrier molecular weight (M.W. 3,000 and 30,000) and 2 etofenprox nano types of chitosan content (70% and 80%). After 14 days of treatment, α-cypermethrin nano formulation showed over 40% mortality against A. gossypii. Therefore, it was confirmed that the insecticide release was controlled through chitosan carrier. Results of the investigation of insecticidal activity of α-cypermethrin nano formulation showed there were no differences between nano types at 4 days after treatment. However, after 14 days, the population increase rate treated with chitosan M.W. 30,000 formulation was -0.037, much lower than that of M.W. 3,000 formulation with 0.231. The result exhibits that chitosan M.W. 30,000 formulation would be a suitable controlled release formulation. On the other hand, etofenprox formulations didn’t show any significant insecticidal effect or persistency difference against both aphid species.
        4,000원