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        검색결과 652

        303.
        2012.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates the flexural properties of multi-walled carbon nanotube (MWCNT) reinforced basalt/epoxy composites under conditions with and without moisture absorption. The basalt/CNT/epoxy composites were fabricated using 1 wt% silanized MWCNTs and kept in seawater for over 4 months. The flexural properties of the moisture absorbed specimens were evaluated and compared with those of dry specimens. The flexural properties of basalt/CNT/epoxy composites were found to decrease with moisture absorption. The flexural strength and modulus of moisture absorbed specimens were 22% and 16% lower, respectively, than those of the dry specimen. Scanning electron microscope examination of the fracture surfaces revealed that the decreases of flexural properties in the moisture absorbed specimen were due to the weakening of interfacial bonding from swelling of the epoxy matrix.
        3,000원
        304.
        2012.06 구독 인증기관·개인회원 무료
        Pluripotent stem cells can be derived from both pre- and post-implantation embryos. Embryonic stem cells (ES cells), derived from inner cell mass (ICM) of blastocyst are naïve pluripotent and epiblast stem cells (EpiSCs) derived from post-implantation epiblast are primed pluripotent. The phenotypes and gene expression patterns of the two pluripotent stem cells are different each other and EpiSCs thought to be in a more advanced pluripotent (primed pluripotent state) than mouse ES cells (naïve pluripotent state). Therefore, we questioned whether EpiSCs are less potential to be differentiated into specialized cell types in vitro. EpiSCs were isolated from 5.5~6.5 day post coitum mouse embryos of the post-implantation epiblast. The EpiSCs could differentiate into all tree germ layers in vivo, and expressed pluripotency markers (Oct4, Nanog). Interestingly, EpiSCs also were able to efficiently differentiate into neural stem cells (NSCs). The NSCs differentiated from EpiSCs (EpiSC-NSCs) expressed NSC markers (Nestin, Sox2, and Musasi), self-renewed over passage 20, and could differentiate into two neural subtypes, neurons, astrocytes and oligodendrocytes. Next, we compared global gene expression patterns of EpiSC-NSCs with that of NSCs differentiated from ES cells and brain tissue. Gene expression pattern of brain tissue derived NSCs were closer to ES cell-derived NSCs than EpiSC-NSCs, indicating that the pluripotent stem cell-derived somatic cells could have different characteristics depending on the origin of pluripotent stem cell types. * This work was supported by the Next Generation Bio-Green 21 Program funded by the Rural Development Administration (Grant PJ 008009).
        305.
        2012.06 구독 인증기관·개인회원 무료
        Recent advances in stem cell biology have shown that terminally differentiated somatic cells can be directly converted to the different types of somatic cells such as neurons and cardiomyocytes with defined sets of transcription factors without going through a pluripotent state. Recently, it was demonstrated that the hepatocyte-specific transcription factors, Hnf4α plus Foxa1, Foxa2 or Foxa3 could erase somatic memory and reset hepatocyte program on the differentiated somatic genome. Here, we show that Foxa3 together with Hnf4α could efficiently reprogram fibroblasts into hepatocytes. However, the direct conversion into hepatocytes is not observed with Hnf4α plus Foxa1. After two weeks of retroviral transduction of Hnf4α and Foxa3, we observed epithelial colonies emerged from starting fibroblasts and were able to establish stable hepatocyte cell lines, namely induced hepatocytes (iHep cells). The iHep cells closely resemble primary hepatocytes in a number of characteristics such as their polygonal shapes, the hepatic gene expression patterns and the presence of E-cadherin signals as determined by immunocytochemistry. In addition, iHep cells show the storage of glycogen as revealed by Periodic acid-Schiff (PAS) staining, indicating that iHep cells are functionally similar to their in vivo counterparts. Taken together, our findings suggest that the combination of hepatic transcription factors, Hnf4α with Foxa3 but not Foxa1 could induce hepatocyte fate on the differentiated somatic cells.
        306.
        2012.06 구독 인증기관·개인회원 무료
        Semen can be divided into two parts. One is cellular part which contains sperms the other is liquid part which is called by seminal plasma. The seminal plasma is a nutritive and protective medium for the sperms. Fructose, which is major energy source, is supplied to sperms swim to female oocyte. Alkalic property protects sperms from hostile environment of female reproductive organ. Also, seminal plasma induces tolerance to preexisted immune cells, and changes intra‐uterine environment to better conditions for fertilized embryos to implant. However, the effects of seminal plasma in in vitro culture of fertilized embryos are unclear. Second fraction of fresh semen was obtained from a normal farm pig. The semen was centrifuged to remove sperms, and then supernatant was filtrated. The filtered seminal plasma was stored in — 30℃. In this study, electrically activated and chemically activated porcine embryos were employed to investigate the developmental rate after 2 hours treatment of none, 0.1%, 0.5%, and 1% seminal plasma in culture media by two days of activation. Both electrically and chemically activated embryos, cleavage rate and cell numbers of blastocysts were not significant difference within four groups. Blastocyst formation rate of electrically activated embryos also did not show significant difference within any groups. However 0.1% seminal plasma treatment group showed significantly increase of blastocyst formation rate in chemically activated group (None; 24.8%, 0.1%; 31.7%, 0.5%; 19.4, and 1%; 16.5%, respectively. p<0.05).
        307.
        2012.06 구독 인증기관·개인회원 무료
        Neural stem cells (NSCs) are self-renewing tripotent cell populations and have capacity of neuronal (neurons) and glial (astrocytes and oligodendrocytes) differentiation. Many researchers have reported that NSCs have therapeutic effects in neurological disease by transplantation. However, it is not easy to obtain NSCs in vitro. Recently, Yamanaka and colleagues showed that somatic cells could be reprogrammed into pluripotent state by enforcing reprogramming factors. Induced pluripotent stem (iPS) cells undergo unlimited self-renewal and have differentiation potential into various types of cells like embryonic stem cells. Direct differentiation into a specialized cell types from iPS cells hold considerable promise for regenerative medicine as well as basic research. Here, we induced differentiation of iPS cells into NSCs in vitro and in vivo, which were compared with embryonic stem (ES) cell-derived NSCs and brain derived NSCs. NSCs from ES and iPS cells were morphologically indistinguishable from brain derived NSCs and stained positive for NSCs markers Nestin and Sox2. ES cells derived NSCs were transcriptionally distinguishable from brain derived NSCs. However, global gene expression pattern were similar but distinct between iPS derived NSCs and brain derived NSCs. Moreover, iPS derived NSCs were spontaneously aggregated upon passaging, formed ES cell like colonies, and finally reactivated Oct4-GFP. The spontaneously reverted GFP-positive cells (iPS-NSC-iPS) expressed similar levels of pluripotency markers (Oct4,Nanog) to ES and iPS cells, and could form germ line chimera. One possible explanation for this phenomenon is that spontaneously re-reprogramming was associated with transgene re-activation when iPS cells were differentiated into NSCs. However, NSCs from dox-inducible iPScells could not be reprogrammed into pluripotent state without doxycycline. Taken together, iPS derived NSCs were morphologically and similar to brain derived NSCs, but differ in gene expression pattern and maintenance. * This work was supported by the Next Generation Bio-Green21 Program funded by the Rural Development Administration (Grant PJ008009).
        308.
        2012.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of this study was to investigate the correlation among bone mineral density(BMD), body composition and body circumference on 20's college women in Hwaseong. A total of 86 subjects were measured with BMD and body composition and body circumference. To evaluate the correlation between BMD and body composition, bone density and body weight, body mass index(BMI), lean body mass, muscle mass, fat mass and body fat mass were compared. The results of this study, weight was considered the strong correlation with BMD than the height and BMI seems to be greater significance rather than the lumbar spine and femur BMD. In addition, the relationship between body composition and BMD, lean body mass, muscle mass, body fat mass were the most relevant factors and BMD. The relationship between BMD and body circumference that have been difficult because of not enough previous studies but somewhat the study showed that association.
        4,000원
        309.
        2012.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out to identify how a self-stretching exercise program affects pain for each body area, pain relief and job satisfaction for care workers. 20 of 40 care workers with musculoskeletal symptom were randomly selected and participated a self-stretching exercise program consisting of 15 motions. The intervention was done five times or more per weeks for 8 weeks and 1 session lasted within 15 minutes. 'Musculoskeletal symptom survey table' of the Korea Occupational Safety and Health Agency(KOSHA) and JDI(Job Descriptive Index) was used for pain on the musculoskeletal symptom and job satisfaction. Survey were done twice before and after the program. The result of this study showed that self-stretching exercise program group(SSPG) relieved from pain significantly in the shoulders(p<.01) and lumbar(p<.05), comparing to the non selfstretching exercise program group(NSPG). Although no significant difference on variations in the JDI appeared in SSPG, the significant reduction appeared from the colleague relationship and organization in NSPG(p<.05). SSPG showed the significant increase on variations in JDI from the job and organization comparing to NSPG. Especially, the improvement on satisfaction for the organization was shown(p<.05). Accordingly, the self-stretching exercise program for care workers can be said to positively affect the overall pain relief and increase on the JDI.
        4,000원
        310.
        2012.03 구독 인증기관 무료, 개인회원 유료
        For reconstituting genetic resource(Korean Native Chicken: KNC) with grem-line chimeric chicken made with cryopreserved biastdermal cells, the experiments were carried out to optimize cryopreservating conditions. Stage X biastdemal cells were collected from KNC embryos and dissociated. Cells were susupended in medium containing cyopretectant and fetal bovine serum(FBS), and distributed into plastic ampules. Cell susupensions were seeded to induce ice formation at —7 ℃ to —35 ℃ at in the experiments, the effect of modification of dissociation way, concentration of FBS and cell density on the vaibility of frezen-thawed cells were investigated by trypan blue exclusion. Then change the way of cell dissociation from pipetting to short time vortexing, viability of frozen-thawed cell tended to be increaced from 29 % to 52 %. Increase concentraition of FBS in frozen medium from 20 % to 80 % made viability of thawed cell from 28 % to 35 %. The viability of thawed cells were 33.9% frozen at 2 embryos/ 0.5ml, and 43.6 % frozen at 20 embryos/0.5 ml. Furthermore, combination of three modifications make big improvement. The viability of frozen-thawed cell was 60 % for combinated method, and 41 % for general method. This result means the advance to practical cryoreservation of blastdermal cell of the KNC(Ogolgye breed).
        4,000원
        311.
        2011.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        UV-Vis 분광광도법과 시간분해 레이저 유도 형광분광법(TRLFS)을 이용하여 흄산의 모사 리간드로 사 용한 2,6-Dihydroxybenzoate(DHB)와 U(VI)의 착물형성반응을 조사하였다. U(VI)-DHB 착물 고유의 전 하이동 흡수 스펙트럼을 분석한 결과, 착물형성반응은 우라늄-리간드 비가 1:1 또는 1:2 착물을 형성하는 이중 평형반응이며, 산도에 따라 착물종의 분포가 변한다는 것을 밝혔다. 계산된 착물형성상수 (log K1and log K2)는 12.4±0.1과 11.4±0.1이다. 이에 더하여, TRLFS 방법으로 조사한 결과, DHB는 U(VI) 화 학종들의 형광 소광제(quencher)로서 역할을 한다는 것을 확인하였다. 특히, 확인된 U(VI) 화학종 모두 (UO2 2+, (UO2)2(OH)2 2+과 (UO2)3(OH)5 +)에서 정적 (static) 및 동적 (dynamic) 소광작용이 공존하는 것으 로 관찰되었다. 시간분해 형광 스펙트럼으로부터 리간드 농도에 따른 U(VI) 화학종의 형광세기와 형광수 명을 측정하였으며, Stern-Volmer 식을 이용하여 분석하였다. 결정된 정적소광계수(KS)는 UO2 2+, (UO2)2(OH)2 2+ 과 (UO2)3(OH)5+에 대하여 각각 4.2±0.1, 4.3±0.1 과 4.34±0.08이다. Stern-Volmer 식 을 이용한 분석 결과, 단일 또는 이중 배위자 구조(mono- and bi-dentate)의 U(VI)-DHB 착물이 모두 정 적소광효과에 관여하는 바닥상태 착물임을 확인하였다.
        4,200원
        314.
        2011.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the influence of handicraft activities on hand promptness and grasp in the elderly. Subjects were comprised of 14 senior citizens between the ages of 70-85, with 7 subjects in the experiment group and 7 in the control group. Subjects in the experiment group practiced various handicrafts twice a day, while those in the control group did not participate in any special activity. The Jebsen Taylor Hand Function Test was used to evaluate the results, while a dynamometer and pinch gauge were used to measure hand promptness and grasp. The 7 senior citizens in the experiment group were able to increase their hand promptness and grasping skills. Conclusively, handicrafts can help improve hand promptness and grasp in the elderly. Furthermore, the development and improvement of such skills can have a positive influence on the daily lives of senior citizens. Such skills are expected to improve the overall neuro-function in the elderly population.
        4,000원
        315.
        2011.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to examine the effects of gait training using functional electrical stimulation on the improvement of hemiplegic patients' functions for balance and gait velocity. The subjects of the experiment were determined to be 10 each hemiplegic patients who had been diagnosed with stroke or brain damage six months or longer earlier assigned to an experimental group and a control group respectively. The subjects were evaluated before the experiment using Tetrax and 10M gait tests, received gait training five times a week for four weeks using functional electrical stimulation and were evaluated after the experiment in the same method as used in the evaluation before the experiment. In order to examine differences between the experimental group that received gait training using functional electrical stimulation and the control group that was treated by functional electrical stimulation and received gait training thereafter, differences between before and after the experiment were analyzed using paired sample t-tests and differences in changes after the experiment between the experimental group and the control group were analyzed using independent sample t-tests in order to compare the two groups with each other. Experimental results showed significant differences in weight bearing, balance and gait velocity between before and after the experiment in the experimental group(p<.05). In the control group, whereas weight bearing and gait velocity did not show any significant difference between before and after the experiment(p>.05), balance showed significant differences(p<.05). Weight bearing, balance and gait velocity change rates showed significant differences between the experimental group and the control group(p<.05). In conclusion, it was indicated that gait training using functional electrical stimulation is effective for enhancing stroke patients' weight bearing rates, balance abilities and gait velocity.
        4,000원
        319.
        2011.05 구독 인증기관·개인회원 무료
        Porcine Circovirus Type2 (PCV2), a single-stranded DNA virus associated with Postweaning multisystemic wasting syndrome(PMWS) of swine, has two major open reading frames, ORF1 and ORF2. The genomic size and molecular weight of ORF2 is respectively 699bp, 28kDa. ORF2 encodes the capsid protein (structural protein) that has type-specific epitopes and is very immunogenic and associated with the induction of neutralizing antibodies, suggesting its potential use in diagnostic assays as well as vaccine development. For efficient production of the capsid proteins, we expressed the PCV2 ORF2 gene with baculovirus in the insect cells. In this study, PCV2 ORF2 was appropriately ligated into the baculovirus transfer vector, pBacPAK9 and pB9-Acpol19-110-EK. Sf21 cells were transfected with a mixture of the purified recombinant transfer vector and bAcGOZA. We generated and purified recombinant viruses containing PCV2 ORF2, and named rAc-B9-PCV2ORF2 and rAc-B9-19-110-EK-PCV2ORF2, respectively. Expression levels of capsid fusion proteins with a partial polyhedrin region of AcNPV more increased than recombinant proteins from non-fusion expressed. Also, expression efficiency increased over time and differed at MOI. As a results, fusion expression of porcine circovirus type2 ORF2 using baculovirus could be utilized as an alternative expression method to produce recombinant antigen against PCV2 infection and is worthy of further investigation.
        320.
        2011.05 구독 인증기관·개인회원 무료
        Aujeszky's disease (AD), also called pseudorabies, is an infectious viral disease caused by an alpha herpes virus and has domestic and wild pigs, as well as a wide range of domestic and wild animals, as the natural host. Aujeszky's disease virus (ADV) virions contain several envelope glycoproteins. Among them, glycoproteins gB, gC and gD are regarded as the major immunogenicity proteins and the antibodies induced by them can neutralize virus in vitro or in vivo. In this study, we investigated expression of these glycoproteins using the bacterial and baculovirus expressionn system. Successful expression of ADV glycoproteins in E. coli was confirmed by SDS-PAGE and Western blot analysis and their optimal expression condition was determined. However, the recombinant proteins generated in the bacterial expression system which lacks glycosylation process frequently lose their biological activity. We tried to express the ADV glycoproteins using the baculovirus expression vector system. The recombinant gB, gC and gD were detected at approximately 100, 60 and 50 kDa on SDS-PAGE and Western blotting, respectively. The optimal expression conditions were determined for MOI(multiplicity of infection) and post-infection days. One MOI and 4 or 5 days post-infection were the best conditions for the expression of the ADV glycoproteins in Sf21 cells. We are currently investigating the antigenicity of recombinant proteins using experimental animals.