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        검색결과 121

        21.
        2012.06 구독 인증기관 무료, 개인회원 유료
        We identified cdf based on screening of the Arabidopsis cDNA library for functional suppressors of the AtBI-1 (a gene described to suppress the cell death induced by Bax gene expression in yeast). The cdf was located on Chr. V and was composed of 5 exons and 4 introns. It encodes a protein of 258 amino acid residues with a molecular weight of 28.8 kDa. The protein has 3 transmembrane domains in the C-terminal region. The cdf has one homologue, named cdf2, which was found in Arabidopsis. Like cdf, cdf2 also induced growth defect in yeast. The effect of the cell growth defect factor was somewhat lower than Bax. cdf could arrest the growth of yeast. Its localization to the nucleus was essential for the suppression of yeast cell proliferation. Morphological abnormality of intracellular network, which is a hallmark of AtBI-1, was attenuated by expression of cdf.
        4,200원
        22.
        2012.03 구독 인증기관 무료, 개인회원 유료
        Differential capacity of the parthenogenetic embryonic stem cells (PESCs) is still under controversy and the mechanisms of its neural induction are yet poorly understood. Here we demonstrated neural lineage induction of PESCs by addition of insulin-like growth factor-2 (Igf2), which is an important factor for embryo organ development and a paternally expressed imprinting gene. Murine PESCs were aggregated to embryoid bodies (EBs) by suspension culture under the leukemia inhibitory factor-free condition for 4 days. To test the effect of exogenous Igf2, 30 ng/ml of Igf2 was supplemented to EBs induction medium. Then neural induction was carried out with serum-free medium containing insulin, transferrin, selenium, and fibronectin complex (ITSFn) for 12 days. Normal murine embryonic stem cells derived from fertilized embryos (ESCs) were used as the control group. Neural potential of differentiated PESCs and ESCs were analyzed by immunofluorescent labeling and real-time PCR assay (Nestin, neural progenitor marker; Tuj1, neuronal cell marker; GFAP, glial cell marker). The differentiated cells from both ESC and PESC showed heterogeneous population of Nestin, Tuj1, and GFAP positive cells. In terms of the level of gene expression, PESC showed 4 times higher level of GFAP expression than ESCs. After exposure to Igf2, the expression level of GFAP decreased both in derivatives of PESCs and ESCs. Interestingly, the expression level of Tuj1 increased only in ESCs, not in PESCs. The results show that IGF2 is a positive effector for suppressing over-expressed glial differentiation during neural induction of PESCs and for promoting neuronal differentiation of ESCs, while exogenous Igf2 could not accelerate the neuronal differentiation of PESCs. Although exogenous Igf2 promotes neuronal differentiation of normal ESCs, expression of endogenous Igf2 may be critical for initiating neuronal differentiation of pluripotent stem cells. The findings may contribute to understanding of the relationship between imprinting mechanism and neural differentiation and its application to neural tissue repair in the future.
        4,000원
        25.
        2011.05 구독 인증기관·개인회원 무료
        An endoparasitoid wasp, Cotesia plutellae parasitized young larval of diamondback moth, Plutella xylostella. Parasitized larva exhibit significant immunosuppression and fail to metamorphose to pupal stage. Especially, during last instar of parasitized P. xylostella, massive nutrients divert from host to wasp development. HTIF (host translation inhibitory factor) encoded in C. Plutella bracovirus (CpBV) play a crucial role in suppressing host usage of amino acids. However, its inhibitory activity is selective by discriminating mRNAs based on their 5’UTR secondary structures. Our RT-PCR and proteomic analysis indicated that arginine kinase mRNA was inhibited by HTIF, but imaginal disc growth factor was not. Arginine kinase and IDGF were persistently expressed in parasitized P. .xylotella with the gradual decrease at the late parasitisation period. Expression of arginine kinase and IDGF were also tissue specific in the gut/epidermis and haemocyte but not in fat bodies. Subsequent analysis of these gene functions by RNA interference explained the benefit of parasitoid for the mRNA discrimination by HTIF.
        26.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper selects length of berth, area of yard, unloading capacity and number of berth as the input indexes, and cargo turnover as output index to research the source of TFP(Total Factor Productivity) growth of 23 main ports in Korea. The major conclusions are as follows. The TFP of the trade ports in Korea is at the fluctuating stage, but it generally displays a rising trend, and it’s growth originate from the growth of technical efficiency. The Growth rates of TFP of trade ports in the different areas are different, and the sources of growth are also different, but the changing trends are basically the same. Four major factors to the increase of TFP are following: competition between ports, reform of property system, harbor-hinterland economic and international trade, modeling, imitation and innovation in management, technology and system.
        4,000원
        27.
        2009.09 구독 인증기관 무료, 개인회원 유료
        Many biological systems are regulated by an intricate set of feedback loops that oscillate with a circadian rhythm of roughly 24 h. This circadian clock mediates an increase in body temperature, heart rate, blood pressure, and cortisol secretion early in the day. Recent studies have shown changes in the amplitude of the circadian clock in the hearts and livers of streptozotocin (STZ)-treated rats. It is therefore important to examine the relationships between circadian clock genes and growth factors and their effects on diabetic phenomena in animal models as well as in human patients. In this study, we sought to determine whether diurnal variation in organ development and the regulation of metabolism, including growth and development during the juvenile period in rats, exists as a mechanism for anticipating and responding to the environment. Also, we examined the relationship between changes in growth factor expression in the liver and clock-controlled protein synthesis and turnover, which are important in cellular growth. Specifically, we assessed the expression patterns of several clock genes, including Per1, Per2, Clock, Bmal1, Cry1 and Cry2 and growth factors such as insulin-like growth factor (IGF)-1 and -2 and transforming growth factor (TGF)-β1 in rats with STZ-induced diabetes. Growth factor and clock gene expression in the liver at 1 week post-induction was clearly increased compared to the level in control rats. In contrast, the expression patterns of the genes were similar to those observed after 5 weeks in the STZ-treated rats. The increase in gene expression is likely a compensatory change in response to the obstruction of insulin function during the initial phase of induction. However, as the period of induction was extended, the expression of the compensatory genes decreased to the control level. This is likely the result of decreased insulin secretion due to the destruction of beta cells in the pancreas by STZ.
        4,000원
        29.
        2009.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Tumor cells under hypoxic conditions are often found due to the rapid outgrowth of their vascular supply, and,in order to survive hypoxia, these cells induce numerous signaling factors. Erk is an important kinase in cell survival, and its activity is regulated by Raf kinases through numerous growth factor receptors. The authors investigated Erk activation and Raf/Erk signaling using the hypoxia-mimetic agent, cobalt chloride (CoCl2), in oral squamous cell carcinoma (OSCC) cells. CoCl2 increases Erk phosphorylation in both a dose- and time-dependent manner. In addition, blocking the activation of epidermal growth factor receptor (EGFR) using PD168393 abolished Erk activation in response to CoCl2, suggesting that Erk phosphorylation by CoCl2 is dependent on EGFR.
        4,000원
        30.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Angiogenesis is a process with a coordinated sequence of endothelial cell division, selective degradation of vascular basement membranes, and surrounding extracellular matrix with migration of theses cells that result in a new capillary growth from preexisting vessels. These processes are controlled by numerous different molecules. Among these, Vascular Endothelial Growth Factor(VEGF) is an endothelial cell-specific mitogen with a potent ability to induce microvessel permeability and angiogenesis. In this study, tissue samples of odontogenic keratocyst(10 cases), ameloblastoma(10 cases), adenomatoid odontogenic tumor(10 cases), calcifying epithelial odontogenic tumor(10 cases), ameloblastic carcinoma(2 cases) were obtained, and all specimen were routinely fixed in 10% formalin and embedded. Serial 5μm thick sections were cut from paraffin blocks. And the immunohistochemical staining, characteristics of VEGF about the cyst & tumor were observed & obtaned the results from this study. We presume that the growth of cyst is depends on not a differentiation but an epithelium & connective tissue. But, in odontogenic tumor, we presumed that the growth of tumor is influenced on inflammation & surrounding stimulus & vascular growth and supply. Therefore, it should be suggested that study on the growth of tumor and vascularity must be carrying out in this immunohistochemical study.
        4,000원
        32.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was performed to investigate the effect of VEGF on in vitro maturation of porcine oocytes. The base medium for IVM, TCM-199 was supplemented with 0.6 mM cysteine, 0.91 mM pyruvate, 10 ng/ml epidermal growth factor, kenamycin, insulin and 10% (V/V) porcine follicular fluid (pFF) as a Group A; Group B was consists of Group A plus 5 ng/ml VEGF; Group C was consists of replacement of pFF by 10% PVA and Group D: was consists of Group C plus 5 ng/ml VEGF. 1. The maturation rate was significantly higher (p<0.05) in control and VEGF+pFF group than other two groups (, respectively). 2. Addition of VEGF without pFF showed a negative effect on oocytes maturation and about 58.26% oocytes were reached to M-II stage. 3. In the parthenogenetic development, the cleavage rate was significantly higher (p<0.05) in control and VEGF+pFF group (, respectively) than other groups (, respectively). 4. The blastocyst formation rate was significantly higher (p<0.05) in VEGF+pFF group () compared to control and other groups. 5. There was no significant difference in cell numbers (inner cell mass or trophectoderm) among these groups.
        4,000원
        37.
        2006.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It is well known that the imbalance between epithelial cell growth and inhibitor factors may cause human epithelial cancer. Over-expression of the epidermal growth factor receptor(EGFR) has been implicated in the development of oral squamous cell carcinoma. ZD1839 inhibits selectively the EGFR tyrosine kinase activity and is clinically used for cancer patients. However the mechanisms by which it exerts its anti-tumor activity remains unclear. This study attempted to determine the mechanisms underlying the effects of ZD1839 on the cellular level and to characterize the effects of ZD1839 with regard to human oral squamous cell carcinoma(OSCC) cell growth. The YD-10B and YD-38 cell lines established from OSCC in the department of Oral Pathology, Yonsei University College of Dentistry and ZD1839(Iressa) were used for this study. The inhibition of cell proliferation induced by ZD1839 was reversible and the lowest dose of ZD1839 that produced statistically significant growth inhibition in YD cell lines were 0.1 μM. The delay in cell cycle progression was induced by 0.1 μM of ZD1839 treatment after 24 hr. This reduction in cell proliferation and cell cycle delay were associated with up-regulation of the cyclin dependent kinase inhibitor(CDKI), P21CIP1/WAF1 and P27KIP1. Reduced expression of cyclin D1 was also observed after treatment with ZD 1839 to YD-38 cells but not to YD-38. The present results suggest that the antiproliferative effects of ZD1839, in vitro was associated with degradation of cyclin D1, which may be used as a possible indicator of a high cell sensitivity to ZD1839.
        4,000원
        38.
        2006.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        소 난포란의 체외 성숙은 과립막 세포, 난자의 핵성숙을 촉진하는 미지의 혈청내의 물질뿐만 아니라, 호르몬이나 생리 활성 인자 등에 의해 촉진됨이 밝혀졌다. 이에 따라 체외 성숙 및 체외 발달에 사용되는 배양액의 조성도 복합 배양액에서 단순 배양액으로 전환을 시도하고 있으며, 체내의 조건에 보다 더 접근하고자 하는 시도들이 수행되고 있다. 본 연구는 한우 난포란의 성숙 시 FGF의 첨가가 체외 성숙율 및 체외 수정 후 배발달율에 미치는 영향에 대하여 조사
        4,000원
        39.
        2005.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Agi ng adversely affects the structure and function of the saliva ry gla nd and leads to ma rked insulin resis t ance that correlates with red uced ins ulin s ignal t ra nsduction, lnsulin-like g rowth factors are k.nown to be regulator involved in embryonic a nd postnatal development with sequences 62% identical t o that of proins ulin , To determine whether i n suli n- like growth facto l' - l, -2, - 1 receptor a l'e involved in the changes in rat salival'y gland by aging, we a na lyzecl the qua nti tation of 19f - 1, -2, - 1 rece ptor mRNA in l'at salivary glancl between 2 weeks and 26 months after bir th using the competiti ve reverse t ra nscriptase-polymerase chain reaction(RT-PCR) methocl Between 2 weeks ancl 2 months age, sharp falls in the qua nt ities of Igf-2 mRNA were observed, W11ereas Igf- 1 receptor mRNA rose by aging, but not sig nifïcantly, The quanti t ies of 19f- l kept by aging, These change seem to be involvecl a role fol' the Igf-2 in sali va ry c1evelopment a ncl earl y growth is incli ca ted, Thus, t he dras tic changes in the qua ntities of Igf-2 mRNA in the ra t sali va ry gla nd by aging seem to be in volved in the development, early growth and homeostasis of sali vary gla nd,
        4,000원
        40.
        2005.06 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to examine the effect of EGF on meiotic maturation and pronuclear (PN) formation of porcine oocytes. Prepubertal gilt cumulus-oocyte-complexes (COCs) aspirated from 2~6mm follicles of abbatoir ovaries were matured in TCM199 containing 0.1mg/ml cysteine, 0.5㎍/ml FSH and LH, and EGF (0, 5, 10, 20, 40 ng/ml) for 22 hr at 39℃ in a humidified atmosphere of 5% CO2 in air. They were then cultured for an additional 22hr without hormones. In Experiment 1, to examine the nuclear maturation at 44hr of culture, the expanded cumulus cells were removed by vortexing for 1 min in 3 mg/ml hyaluronidase. The oocytes were fixed in acetic acid: methanol (1:3, v/v) at least for 48 hr and stained with 1% orcein solution for 5 min. Nuclear status was classified as germinal vesicle (GV), germinal vesicle breakdown (GVBD), prophase-metaphase I (PI-MI), and PII-MII under microscope. In Experiment 2, to investigate PN formation, oocytes were fertilized with Percoll-treated freshly ejaculated sperm (1 x10 5 cells/ml) in mTBM with 0.3% BSA and 2mM caffeine for 5hr, and cultured in NCSU-23 medium with 0.4% BSA. At 6hr of culture, the embryos were fixed in 3.7% formaldehyde for 48hr and stained with 10ug/ml propidium iodide for 30 min. PN status was classified as no or one PN (unfertilized), 2 PN (normal fertilized) and ≥3 PN (polyspermy). Differences between groups were analyzed using one-way ANOVA after arc-sine transformation of the proportional data. The rate of oocytes that had reached to PII-MII were significantly (P<0.05) higher in all groups added EGF than that of non-treated group (67%), but it did not differ among the all added groups (86%, 85%, 79% and 81%, in 5, 10, 20 and 40 ng/ml EGF, respectively). No differences on the incidence of 2PN were observed in all treated groups (25%, 30%, 33%, 29% and 29%, in 0, 5, 10, 20 and 40 ng/ml EGF, respectively), however, in non-treated group, polyspermy tended to be increased (66% vs 58%, 54%, 52% and 55%, 0 vs. 5, 10, 20, 40 ng/ml EGF, respectively). These results suggest that EGF can be effectively used as an additive for enhancing oocyte maturation and reducing the incidence of polyspermy in pig.
        4,000원
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