• Journal of Ginseng Research
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• 제24권1호
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• pp.8-17
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• 2000

스테로이드 호르몬의 일종인 에스트로젠은 생식기능에 영향을 미치는 것 외에 학습 및 기억과 관련된 기능에도 영향을 미치는 것으로 알려져 있다. 최근, 에스트로젠은 기억과 관련된 뇌세포 신 경망의 발달과 뇌 기능 장애를 방지할 수 있다는 부분에서 상당한 관심의 대상이되고 있다. 그러나 에스트로젠 대체 치료가 폐경기의 많은 여성들에게 도움을 주기도 하지만 여러 부작용을 유발하는 것으로도 알려져 있다 인삼 역시도 스테로이드 특성을 보이며 에스트로젠과 유사한 화학구조를 가지는 여러 성분을 가지고 있다. 본 실험의 목적은 첫째로 공간 기억력을 측정하기에 여러 장점을 가지고 있으면서 다른 어떠한 행동학적 실험보다 학습과 기억의 동물 모텔로 잘 알려진 방법인 Morris water maze를 이용하여 에스트로젠의 효과를 확인하고, 두 번째는 인삼이 학습과 기억에서 에스트로젠과 같은 효과를 나타낼 수 있는지를 확인하는 것이다. 본 실험은 인위적으로 난소를 제거한 쥐에 17$\beta$-estradiol(100~250 $\mu\textrm{g}$/ml), panaxadiol(PD), panaxatriol(PT) sapo-nins(15~100 $\mu\textrm{g}$/ml)을 sesame oil에 녹인 capsule을 implant했다. 첫 번째 실험에서 난소를 제거한 쥐에 에스트로젠을 투입했을때 학습과 기억의 효과를 확인했다. 두 번째 실험에서는 난소를 제거한 쥐에 3가지 다른 농도에서의 PD, PT를 투입했을 때 학습과 기억에 대한 에스트로젠의 효과와 비교해 보았다. 2주 동안의implant 후 water maze 실험결과 세 그룹 모두 난소를 제거한 그룹보다 기억력이 향상되었다 이러한 결과를 토대로 에스트로젠이 학습과 기억에 영향을 준다는 것을 확인할 수 있었고 PD, PT 또한 학습과 기억에 관련된 행동에서 에스트로젠과 같은 효과를 나타낼 수 있다는 것을 확인할 수 있었다. 이러한 동물모델에서의 연구를 통하여 인삼이 에스트로젠 장기결핍치료에서 나타나는 여러 호르몬 부작용을 극복할 수 있는 에스트로젠 대체물질로 개발되어 기억력 저하를 수반하는 Alzheimer's disease 및 여러 퇴행성 중추신경 질환의 치료제로 대체의학의 natural compound이용에 그 기초 기전을 제공할 수 있으리라 여긴다.

• 식물조직배양학회지
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• 제27권6호
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• pp.423-428
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• 2000

In 1997 when cloned sheep Dolly and soon after Polly were born, it had become head-line news because in the former the nucleus that gave rise to the lamb came from cells of six-year-old adult sheep and in the latter case a foreign gene was inserted into the donor nucleus to make the cloned sheep produce human protein, factor IX, in e milk. In the last few years, once the realm of science fiction, cloned mammals especially in livestock have become almost commonplace. What the press accounts often fail to convey, however, is that behind every success lie hundreds of failures. Many of the nuclear-transferred egg cells fail to undergo normal cell divisions. Even when an embryo does successfully implant in the womb, pregnancy often ends in miscarriage. A significant fraction of the animals that are born die shortly after birth and some of those that survived have serious developmental abnormalities. Efficiency remains at less than one % out of some hundred attempts to clone an animal. These facts show that something is fundamentally wrong and enormous hurdles must be overcome before cloning becomes practical. Cloning researchers now tent to put aside their effort to create live animals in order to probe the fundamental questions on cell biology including stem cells, the questions of whether the hereditary material in the nucleus of each cell remains intact throughout development, and how transferred nucleus is reprogrammed exactly like the zygotic nucleus. Stem cells are defined as those cells which can divide to produce a daughter cell like themselves (self-renewal) as well as a daughter cell that will give rise to specific differentiated cells (cell-differentiation). Multicellular organisms are formed from a single totipotent stem cell commonly called fertilized egg or zygote. As this cell and its progeny undergo cell divisions the potency of the stem cells in each tissue and organ become gradually restricted in the order of totipotent, pluripotent, and multipotent. The differentiation potential of multipotent stem cells in each tissue has been thought to be limited to cell lineages present in the organ from which they were derived. Recent studies, however, revealed that multipotent stem cells derived from adult tissues have much wider differentiation potential than was previously thought. These cells can differentiate into developmentally unrelated cell types, such as nerve stem cell into blood cells or muscle stem cell into brain cells. Neural stem cells isolated from the adult forebrain were recently shown to be capable of repopulating the hematopoietic system and produce blood cells in irradiated condition. In plants although the term$\boxDr$ stem cell$\boxUl$is not used, some cells in the second layer of tunica at the apical meristem of shoot, some nucellar cells surrounding the embryo sac, and initial cells of adventive buds are considered to be equivalent to the totipotent stem cells of mammals. The telomere ends of linear eukaryotic chromosomes cannot be replicated because the RNA primer at the end of a completed lagging strand cannot be replaced with DNA, causing 5' end gap. A chromosome would be shortened by the length of RNA primer with every cycle of DNA replication and cell division. Essential genes located near the ends of chromosomes would inevitably be deleted by end-shortening, thereby killing the descendants of the original cells. Telomeric DNA has an unusual sequence consisting of up to 1,000 or more tandem repeat of a simple sequence. For example, chromosome of mammal including human has the repeating telomeric sequence of TTAGGG and that of higher plant is TTTAGGG. This non-genic tandem repeat prevents the death of cell despite the continued shortening of chromosome length. In contrast with the somatic cells germ line cells have the mechanism to fill-up the 5' end gap of telomere, thus maintaining the original length of chromosome. Cem line cells exhibit active enzyme telomerase which functions to maintain the stable length of telomere. Some of the cloned animals are reported prematurely getting old. It has to be ascertained whether the multipotent stem cells in the tissues of adult mammals have the original telomeres or shortened telomeres.

• Journal of Periodontal and Implant Science
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• 제32권1호
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• pp.199-211
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• 2002

Digital substraction technique and computer-assisted densitometirc analysis detect minor change in bone density and thus increase the diagnostic accuracy. This advantage as well as high sensitivity and objectivity which precludes human bias have drawn interest in radiologic research area. The objectives of this study are to verify if Radiographic density can be recognized in linear pattern when density profile of standard periapical radiograph with the aluminium stepwedge as the reference, was investigated under varies circumstances which can be encountered in clinical situations, and in addition to that to obtain mutual relationship between the existing standard radiographic system, and future digital image systems, by confirming the corelationship between the standard radiograph and Digora system which is a digital image system currently being used. In order to make quantitative analysis of the bone tissue, digital image system which uses high resolution automatic slide scanner as an input device, and Digora system were compared and analyzed using multifunctional program, Brain3dsp. The following conclusions were obtained. 1. Under common clinical situation that is 70kVp, 0.2 sec., and focal distance 10cm, Al-Equivalent image equation was found to be Y=11.21X+46.62 $r^2=0.9898$ in standard radiographic system, and Y=12.68X+74.59, $r^2=0.9528$ in Digora system, and linear relation was confirmed in both the systems. 2. In standard radiographic system, when all conditions were maintained the same except for the condition of developing solution, Al-Equivalent image equation was Y=10.07X+41.64, $r^2=0.9861$ which shows high corelationship. 3. When all conditions were maintained the same except for the Kilovoltage peak, linear relationship was still maintained under 60kVp, and Al-Equivalent image equation was Y=14.60X+68.86, $r^2=0.9886$ in the standard radiograhic system, and Y=13.90X+80.68, $r^2=0.9238$ in Digora system. 4. When all conditions were maintained the same except for the exposure time which was varied from 0.01 sec. to 0.8 sec., Al-Equivalent image equation was found to be linear in both the standard radiographic system and Digora system. The R-square was distributed from 0.9188 to 0.9900, and in general, standard radiographic system showed higher R-square than Digora system. 5. When all conditions were maintained the same except for the focal distance which was varied from 5cm to 30cm, Al-Equivalent image equation was found to be linear in both the standard radiographic system and Digora system. The R-square was distributed from 0.9463 to 0.9925, and the standard radiographic system had the tendency to show higher R-square in shorter focal distances.