• Molecules and Cells
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• 제24권1호
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• pp.9-15
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• 2007

To investigate the effects of chitosan on the redifferentiation of dedifferentiated chondrocytes, we used chondrocytes obtained from a micromass culture system. Micromass cultures of chick wing bud mesenchymal cells yielded differentiated chondrocytes, but these dedifferentiated during serial monolayer subculture. When the dedifferentiated chondrocytes were cultured on chitosan membranes they regained the phenotype of differentiated chondrocytes. Expression of protein kinase $C{\alpha}$ ($PKC{\alpha}$) increased during chondrogenesis, decreased during dedifferentiation, and increased again during redifferentiation. Treatment of the cultures with phorbol 12-myristate 13-acetate (PMA) inhibited redifferentiation and down-regulated $PKC{\alpha}$. In addition, the expression of p38 mitogen-activated protein (MAP) kinase increased during redifferentiation, and its inhibition suppressed redifferentiation. These findings establish a culture system for producing chondrocytes, point to a new role of chitosan in the redifferentiation of dedifferentiated chondrocytes, and show that $PKC{\alpha}$ and p38 MAP kinase activities are required for chondrocyte redifferentiation in this model system.

• 대한핵의학회지
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• 제35권6호
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• pp.393-397
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• 2001

Surgery, radioiodine therapy, and thyroxine treatment represent established therapeutic measures of proven efficacy for the treatment of well-differentiated thyroid cancer. However, in some cases, dedifferentiation is noted and it makes tumors refractory to conventional treatment. Recently, retinoic acid redifferentiation therapy was evaluated in several in vitro and in vivo studios. We report a patient with papillary carcinoma in whom metastatic lesions became radioiodine negative on high-dose therapy. Redifferentiation therapy with retinoic acid induced radioiodine uptake in some of metastatic tissues. Side effects such as xerostomia and cheilosis were mild. We recommend retinoic acid redifferentiation therapy as an option for the treatment of thyroid cancer with negative radioiodine uptake after high-dose radioiodine therapy.

• Animal cells and systems
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• 제5권2호
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• pp.91-99
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• 2001

Vertebrates regenerate tissues in three ways: proliferation of cells that maintain some or all of their differentiated structure and function, redifferentiation of mature cells followed by proliferation and redifferentiation into the same cell type or transdetermination to another cell type, and activation of restricted lineage stem cells, which have the ability to transdetermine to different lineages under the appropriate conditions. The behavior of the cells during regeneration is regulated by growth factors and extracellular matrix molecules. Some non-regenerating tissues are now known to harbor stem cells which, though they form scar tissue in vivo, are capable of producing new tissue-specific cells in vitro, suggesting that the injury environment inhibits latent regenerative capacity. Regenerative medicine seeks to restore tissues via transplantation of stem cell derivatives, implantation of bioartificial tissues, or stimulation of regeneration in vivo. These approaches have been partly successful, but several research issues must be addressed before regenerative medicine becomes a clinical reality.

• 식물조직배양학회지
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• 제26권4호
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• pp.223-227
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• 1999

본 연구는 글라디올러스 캘러스로부터의 재분화 조건을 구명함으로써 캘러스 배양시스템을 확립하는데 기여하고자 하였다. 글라디올러스 캘러스로부터의 유식물체 획득은 캘러스를 2,4-D 무첨가 1/2 MS고체배지에 치상한 후 24시간 일장하에서 15$^{\circ}C$로 배양하였을 때 효과적이었다. 캘러스로부터의 기관형성에 미치는 배양방법의 영향을 검토한 결과, 부정근의 형성은 액체진탕배양이 그리고 부정아의 형성은 액채정치배양이 각각 우수한 것으로 확인되었다. 본 실험의 결과를 통해 글라디올러스 ‘Topaz' 캘러스로부터의 재분화를 위한 최적 배양 조건을 선발하는 한편, 액체진탕배양법에 의해 기관-캘러스 혼합체를 유도할 수 있었으며, 이를 이용하여 기내 유식물체를 대량생산할 수 있는 가능성을 확인할 수 있었다.

• Archives of Plastic Surgery
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• 제47권5호
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• pp.392-403
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• 2020

Severe cartilage defects and congenital anomalies affect millions of people and involve considerable medical expenses. Tissue engineering offers many advantages over conventional treatments, as therapy can be tailored to specific defects using abundant bioengineered resources. This article introduces the basic concepts of cartilage tissue engineering and reviews recent progress in the field, with a focus on craniofacial reconstruction and facial aesthetics. The basic concepts of tissue engineering consist of cells, scaffolds, and stimuli. Generally, the cartilage tissue engineering process includes the following steps: harvesting autologous chondrogenic cells, cell expansion, redifferentiation, in vitro incubation with a scaffold, and transfer to patients. Despite the promising prospects of cartilage tissue engineering, problems and challenges still exist due to certain limitations. The limited proliferation of chondrocytes and their tendency to dedifferentiate necessitate further developments in stem cell technology and chondrocyte molecular biology. Progress should be made in designing fully biocompatible scaffolds with a minimal immune response to regenerate tissue effectively

• 한국토양동물학회지
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• 제6권1_2호
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• pp.1-6
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• 2001

Although the earthworm is an important animal species capable of regenerating missing body part, earthworm regeneration is not well understood at the tissue, cell and molecular levels. In order to understand the developmental changes of blastema during earthworm tail regeneration, the formation and development blastema during regeneration was investigated by histological analysis. Within 1 day after amputation, dediffentiating blastemal cells appeared in coelomic side of longitudinal muscle layer. At 3 days postamputation, proliferating blastemal cells migrated into coelum and blastema was formed beneath wound epithelium around 7 days after amputation. Segmentation of blastema was observed around 2 weeks after amputation followed by redifferentiation of nephridium, intestine, setae and septa.

• Journal of Plant Biotechnology
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• 제8권1호
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• pp.21-25
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• 2006

Phragmites australis (reed) has received much attention as being one of the principle emergent aquatic plants for treating industrial and civil wastewater. Plant regeneration via plant tissue culture in p. australis was investigated. Three types of callus were identified from seeds on N6 medium plus 4.5 UM 2,4-dichlorophenoxyacetic acid (2,4-D). Yellow compact type showed the best redifferentiation, whereas white compact type and yellow friable were not competent to differentiate into plane. Solid medium culture was better than liquid suspension culture for enhancing callus growth when N6 medium supplemented with 4.5 ${\mu}M$ 2,4-D was used. Phytagel, as a gelling agent, was superior to agar in plant regeneration on N6 medium, supplemented with 9.4 ${\mu}M$ kinetin and 0.54 ${\mu}M$ $\alpha$-naphthaleneacetic acid (NAA). Transfer of the plantlets regenerated from kinetin and NAA-supplemented N6 medium to growth regulator-free MS medium enhanced the further development of the plantlets. Plantlets on subsequently grown to maturity when tansferred to potting soil. The regenerated plants exhibited morphologically normal. The system for plant regeneration of P. australis enables to propagate elite lines on a large scale for water purification in the ecosystem

• KSBB Journal
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• 제7권3호
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• pp.216-221
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• 1992

본 연구는 고추 잎 절편으로부터 유도한 callus로부터 체세포 배형성에 따른 peroxidase, esterase 및 MDH의 활성 및 전기영동적 변화를 비교 분석하여 세포분화에 따른 생리, 생화학적인 변화를 알아보고자 하였다. 고추 잎 절편에서 유도된 callus는 호르몬이 첨가 되지 않은 MS 액체배지에서 체세포배를 유도하였을 때 배양 7일째 peroxidase, esterase, MDH의 효소 활성이 가장 높게 나타났으며 특히 peroxidase의 활성도는 배양 12일째 세포내에 비해 배로 방출된 효소의 활성이 4배 정도 높았다. 이와같이 페세포 배형성에 따른 isozyme 의 활성도 및 전기영동적 양상의 배형성과 재분화 과정을 연구하는데 유용할 것으로 사료된다.

• 대한핵의학회지
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• 제35권3호
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• pp.117-124
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• 2001

Serum thyroglobulin measurement and I-131 whole-body scintigraphy (WBS) are well-established methods for the detection of recurrence in the follow-up of patients with thyroid carcinoma. However, inconsistent results are observed frequently, and these two methods are not always able to detect recurrence. In some patients, serum thyroglobulin level is elevated but the WBS is negative, because the recurrent tumor is too small and below the sensitivity of the diagnostic scan, or there is a dissociation between thyroglobulin synthesis and the iodine frapping mechanism. In such cases, various nuclear imaging methods including Tl-201 Tc-99m-sestamibi, and F-18-FDG PET can be used besides anatomical imaging methods. Among them, FDG PET localizes recurrent lesions in WBS-negative thyroid carcinoma with high accuracy. Several studies have suggested that empirical high-dose I-131 therapy resulted in a high rate of visualization in post-therapy scans with evidence of subsequent improvement. An important question is when to operate on patients with recurrent tumor. We believe that surgical removal is the best means of treatment for patients with localized persistent tumor, despite the high-dose I-131 therapy. with tumor in thyroid remnant, and with isolated recurrence in the lymph node, lung or bone. In addition, we recommend palliative resection of locally unresectable mass with subsequent treatment with high-dose I-131 therapy. Before I-131 therapy, the evaluation of sodium-iodide symporter expression in thyroid carcinoma can predict iodine uptake. Retinoic acid is known to induce redifferentiation, and to enhance I-131 uptake in thyroid carcinoma. Retinoic acid therapy may represent an alternative approach before high-dose I-131 therapy.

• 한국발생생물학회지:발생과생식
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• 제2권1호
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• pp.53-62
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• 1998

리소솜 acid phosphatase(LAP)를 포함하는 리소솜 산성 가수 분해 효소는 세포 내,외 성분의 분해에 중요한 기능을 수행하며, 유미 양서류의 다리 재생 과정에서 LAP의 효소 활성도는 탈분화시기에 특이적으로 증가하는 것으로 알려져 있다. 본 연구에서는 멕시코산 도룡뇽의 일종인 axolotl(Ambystoma mexicanum)의 다리 재생 가정에서 정상적인 다리 재생 조직과 retinoic acid (RA)가 처리된 다리 재생 조직에서 LAP의 분포 및 발현을 면역 화학적 방법으로 조사하였다. Axolotl의 다리 재생 조직에서 한국산 도룡뇽(Hynobius leechii)의 LAP에 대한 단일 항체를 이용한 면역 반응도는 줄 탈분화시기에 있는 wound epidermis와 미분화된 중배엽성 세포인 blastema 세포, 탈분화 상태의 근육과 연골 부위 세포에서 나타나는 것으로 조사되었다. 또한 LAP의 면역 반응도는 재생단게의 초기에 점차 증가하여 탈분화시기 동안 최대치에 도달하였으며, 재분화가 시작되면서 basal level 까지 서서히 감소하는 것으로 나타나\ulcorner. 유미 양서류의 다리 재생 과정에서 골격 패턴의 복제를 유발시키는 것으로 알려져 있는 RA 처리는 LAP의 면역 반응도를 강화시키는 것으로 나타나\ulcorner. 즉, RA가 처리된 다리 재생 조직에서 LAP의 면역 반응도는 정상적인 다리 재생 조직에서 보다 강하게 나타났으며, 면역 반응도가 나타나는 시기 또한 연장되는 것으로 조사되었다. 이와 같은 결과는 다리 재생 조직에서 RA 처리가 탈분화시기의 연장에 관여한다는 것을 시사하고 있다.