• 한국문헌정보학회지
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• 제36권4호
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• pp.227-244
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• 2002

이 연구의 목적은 현재 구축되어 있는 PDL(Personal Digital Library)의 한계와 문제점을 분석하고, 이용자 중심의 PDL을 구축하기 위한 개발 철학을 제시하는데 있다. 이 연구에서 개발하고자 하는 PDL은 대학생을 잠재적 이용자 그룹으로 설정하고 있다. 이에 이 연구에서는 대학생들의 정보추구행태와 관련한, 특히, 지식활동과 관련한 정보요구와 이용 그리고 관리 행태에 대해 분석하였다. 이렇게 분석한 자료에 기초하여 대학생들이 바라는 PDL에 대한 시스템 요구사항을 개념적으로 제시하였다.

• Journal of Periodontal and Implant Science
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• 제34권1호
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• pp.205-221
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• 2004

Periodontal ligament(PDL) cells have been known as playing an important roles in periodontal regeneration and gingival fibroblasts are also important to periodontal regeneration by forming connective tissue attachment. There were rare studies about the gene expression patterns of PDL cells and gingival fibroblasts, therefore in this study, we tried cDNA microarray-based gene expression monitoring to explain the functional differences of PDL cells and gingival fibroblasts in vivo and to confirm the characteristics of PDL cells. Total RNA were extracted from PDL cells and gingival fibroblasts of same person and same passages, and mRNA were isolated from the total RNA using Oligotex mRNA midi kit(Qiagen) and then fluorescent cDNA probe were prepared. And microarray hybridization were performed. The gene expression patterns of PDL cells and gingival fibroblasts were quite different. About 400 genes were expressed more highly in the PDL cells than gingival fibroblasts and about 300 genes were more highly expressed in the gingival fibroblasts than PDL cells. Compared growth factor- and growth factor receptor-related gene expression patterns of PDL cells with gingival fibroblasts, IGF-2, IGF-2 associated protein, nerve growth factor, placental bone morphogenic protein, neuron-specific growth- associated protein, FGF receptor, EGF receptor-related gene and PDGF receptor were more highly expressed in the PDL cells than gingival fibroblasts. The results of collagen gene expression patterns showed that collagen type I, type III, type VI and type VII were more highly expressed in the PDL cells than gingival fibroblasts, and in the gingival fibroblasts collagen type V, XII were more highly expressed than PDL cells. The results of osteoblast-related gene expression patterns showed that osteoblast specific cysteine-rich protein were more highly expressed in the PDL cells than gingival fibroblasts. The results of cytoskeletal proteins gene expression patterns showed that a-smooth muscle actin, actin binding protein, smooth muscle myosin heavy chain homolog and myosin light chain were more highly expressed in the PDL cells than gingival fibrobalsts, and ${\beta}-actin$, actin-capping protein(${\beta}$ subunit), actin- related protein Arp3(ARP) and myosin class I(myh-1c) were more highly expressed in the gingival fibroblasts than PDL cells. Osteoprotegerin/osteoclastogenesis inhibitory factor(OPG/OCIF) was more highly expressed in the PDL cells than gingival fibroblasts. According to the results of this study, PDL cells and gingival fibroblasts were quite different gene expression patterns though they are the fibroblast which have similar shape. Therefore PDL cells & gingival fibroblasts are heterogeneous populations which represent distinct characteristics. If more studies about genes that were differently expressed in each PDL cells & gingival fibroblasts would be performed in the future, it would be expected that the characteristics of PDL cells would be more clear.

• 한국도서관정보학회지
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• 제33권3호
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• pp.193-214
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• 2002

이 연구는 최근, 대학도서관 뿐만 아니라 특수ㆍ전문도서관 등에서도 자주 나타나고 있는 PDL의 등장 배경과 지식기반사회에서 PDL의 개념이 어떻게 형성되었는가를 살펴보았다. 또한, 이와 관련한 사례들을 함께 살펴봄으로써 현행 PDL 개념의 확장에 관한 발전적 제안을 발견하게 되었는데, 이것은 향후, 이용자 중심의 PDL모형을 개발하는데 있어 중요한 기초 자료가 될 것이라 생각한다. 이 연구에서 밝혀진 PDL모형 개발시 유의점은 다음과 같다. \circled1 개인화가 발생하게 된 사회 환경의 변화에 그 의미를 찾아야 한다. \circled2 제공되어지는 콘텐츠는 제한을 두지 않아야 한다. \circled3 개인의 요구조건을 충분히 만족할 수 있는 시스템이어야 한다 \circled4 시스템구현 방법은 공개적이어야 하며, 계속적인 지원이 가능하도록 오픈소스 개념으로 개발되어져야 한다.

• 대한후두음성언어의학회지
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• 제20권1호
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• pp.25-30
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• 2009

Introduction: 585 nm Pulsed dye laser (PDL) laryngeal surgery is based on the photodynamic characteristics of selective photothermolysis and photoangiolysis and recently considered to be the treatment for a variety of benign laryngeal disease. Objective: To review the indications and outcome of office-based 585nm PDL surgery and summarize new developments. Method: Retrospective study involving 402 patients was performed, The PDL surgery could be applied to various laryngeal diseases such as laryngeal papilloma, vocal fold dysplasia, laryngeal granuloma, vocal polyp, capillarectasia, scarred vocal fold and sulcus vocalis. Results : The physiologic properties of the vascular specificity of PDL provide many advantages and appear to be effective for laryngeal treatment. The PDL resulted in precise, selective coagulation of the microvasculature without damage to the surrounding tissue. Therefore PDL surgery is safe and effective for office-based treatment of benign laryngeal disease and for all patients regardless of their overall medical condition. Conclusion: PDL surgery provides potential benefits and advantage for treating common benign laryngeal disease.

• Journal of Periodontal and Implant Science
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• 제26권1호
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• pp.89-102
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• 1996

The goal of periodontal therapy is to regenerate the loss of periodontal attachment appratus. Current theories suggest the cells of the periodontium have the capacity, when appropriately triggered, to actively participate in restoring connective tissues, including mineralized tissues. This study was performed to define the hard tissue regeneration effect of periodontal ligament(PDL) cells in vitro and the effect of rate of the composition in gingival fibroblasts(GF) on the hard tissue regeneration capacity of PDL cells. For this study, Cell growth rate, alkaline phosphatase(Al.Pase) levels and the ability to produce mineralized nodules in co-culture of PDL cells and GF were examined. The results were as follows : 1. At 7 and 15 days, Cell growth of co-culture of PDL and GF(50 : 50) was greater than that of PDL cells or GF alone(P>0.05). 2. Measurements of ALPase levels indicated that PDL cells had significantly higher activity when compared with that of co-culture groups and GF only(p<0.05). And, ALPase activity in 10 days was higher than that of 7 days(P>0.05) 3. The tendency of formation of the mineralized nodule were observed dose-depend pattern of PDL cells. There was statistically significant difference among group 1(PDL 100%), 2(PDL 70% : GF 30%), and 3(PDL 50% : GF 50%)(P<0.01). But, there was no difference among group 3, 4(PDL 30% GF 70%), and 5(GF 100%). 4. Also, the number of nodule was greater in co-culture of PDL 70% and GF 30% than in culture of PDL 70%(P<0.05) From the above results, it is assumed that the co-culture of PDL cells and GF stimulates the cell growth, which is not that of PDL cells but GF. And, the activity of ALPase depends on the ratio of PDL cells, and ALPase may relate to the initial phase of nodule formation. Also, it is thought that the calcified nodule formation principally depends on PDL cells, is inhibited by GF, and affected by cell density.

• 대한치과교정학회지
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• 제42권6호
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• pp.307-317
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• 2012

Objective: The purpose of this study was to investigate the isolation and characterization of multipotent human periodontal ligament (PDL) stem cells and to assess their ability to differentiate into bone, cartilage, and adipose tissue. Methods: PDL stem cells were isolated from 7 extracted human premolar teeth. Human PDL cells were expanded in culture, stained using anti-CD29, -CD34, -CD44, and -STRO-1 antibodies, and sorted by fluorescent activated cell sorting (FACS). Gingival fibroblasts (GFs) served as a positive control. PDL stem cells and GFs were cultured using standard conditions conducive for osteogenic, chondrogenic, or adipogenic differentiation. Results: An average of $152.8{\pm}27.6$ colony-forming units was present at day 7 in cultures of PDL stem cells. At day 4, PDL stem cells exhibited a significant increase in proliferation (p < 0.05), reaching nearly double the proliferation rate of GFs. About $5.6{\pm}4.5%$ of cells in human PDL tissues were strongly STRO-1-positive. In osteogenic cultures, calcium nodules were observed by day 21 in PDL stem cells, which showed more intense calcium staining than GF cultures. In adipogenic cultures, both cell populations showed positive Oil Red O staining by day 21. Additionally, in chondrogenic cultures, PDL stem cells expressed collagen type II by day 21. Conclusions: The PDL contains multipotent stem cells that have the potential to differentiate into osteoblasts, chondrocytes, and adipocytes. This adult PDL stem cell population can be utilized as potential sources of PDL in tissue engineering applications.

• Journal of Periodontal and Implant Science
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• 제41권1호
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• pp.30-43
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• 2011

Purpose: Under different culture conditions, periodontal ligament (PDL) stem cells are capable of differentiating into cementoblast-like cells, adipocytes, and collagen-forming cells. Several previous studies reported that because of the stem cells in the PDL, the PDL have a regenerative capacity which, when appropriately triggered, participates in restoring connective tissues and mineralized tissues. Therefore, this study analyzed the genes involved in mineralization during differentiation of human PDL (hPDL) cells, and searched for candidate genes possibly associated with the mineralization of hPDL cells. Methods: To analyze the gene expression pattern of hPDL cells during differentiation, the hPDL cells were cultured in two conditions, with or without osteogenic cocktails (${\beta}$-glycerophosphate, ascorbic acid and dexamethasone), and a DNA microarray analysis of the cells cultured on days 7 and 14 was performed. Reverse transcription-polymerase chain reaction was performed to validate the DNA microarray data. Results: The up-regulated genes on day 7 by hPDL cells cultured in osteogenic medium were thought to be associated with calcium/iron/metal ion binding or homeostasis (PDE1A, HFE and PCDH9) and cell viability (PCDH9), and the down-regulated genes were thought to be associated with proliferation (PHGDH and PSAT1). Also, the up-regulated genes on day 14 by hPDL cells cultured in osteogenic medium were thought to be associated with apoptosis, angiogenesis (ANGPTL4 and FOXO1A), and adipogenesis (ANGPTL4 and SEC14L2), and the down-regulated genes were thought to be associated with cell migration (SLC16A4). Conclusions: This study suggests that when appropriately triggered, the stem cells in the hPDL differentiate into osteoblasts/cementoblasts, and the genes related to calcium binding (PDE1A and PCDH9), which were strongly expressed at the stage of matrix maturation, may be associated with differentiation of the hPDL cells into osteoblasts/cementoblasts.

• Journal of Periodontal and Implant Science
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• 제37권3호
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• pp.479-488
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• 2007

In spite of the attention given to the study of mesenchymal stem cells derived periodontal ligament (PDL), there is a lack of information about canine PDL cells. In this study, we characterized canine PDL cells to clarify their stem cell properties, including self renewal, proliferate rate, stem cell markers and multipotency. PDL cells were obtained from extracted premolars of canines, following a colony forming assay and proliferation rate of sub-confluent cultures of cells for self-renewal, immunostaining for STRO-1 and CD146/MUC18 and a differentiation assay for multipotency. Canine PDL cells formed single-cells colonies and 25% of the PDL cells displayed positive staining for BrdU. The cells expressed the mesenchymal stem-cell markers, STRO-1 and CD146/MUC18. Under defined culture conditions, the cells differentiated into osteoblasts and adipocytes, but the cells didn't differentiated into chondrocytes. The findings of this study indicated that the canine PDL cells possess crucial stem cells properties, such as self-renewal and multipotency, and express the mesenchymal stem cell markers on their surface. The isolation and characterization of canine PDL cells makes it feasible to pursue preclinical models of periodontal regeneration in canine.

• 한국광학회지
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• 제12권1호
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• pp.32-39
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• 2001

본 논문에서는 10Gb/s의 광전송 시스템에서 편광모드별 광손실(PDL)이 개입되었을 때, 전송 시스템이 받는 영향과 편광 모드분산에 대한 보상회로의 실효성이 어떻게 감소되는지를 컴퓨터 모의 실험을 통해 분석하였다. 그 결과 편광모드별 광손실의 양이 늘어남에 따라서 시스템의 성능은 비례하여 감소되는 형태를 보였으며 편광모드 분산에 대한 보상회로의 성능 또한 감소되었다. 이는 모드별 광손실의 효과가 포함되었을 때에는 단순한 속도 차이 외에 펄스의 모양이 그대로 유지되는 축인 PSP의 직교성이 상실되기 때문에 펄스의 속도 차이에 왜곡이 더해져서 보상이 어렵기 때문이다. 따라서 PDL 소자가 다수 포함되는 장거리 광대역 광전송 시스템에서의 편광모드 분산에 대한 보상회로 설계 시에 이에 대한 숙고가 필요함을 알수있었다.

• 한국광학회:학술대회논문집
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• 한국광학회 2002년도 하계학술발표회
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• pp.170-171
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• 2002

근래에 광통신의 속도가 10Gbps 이상 증가하면서, 고려하지 않았던 편광과 관련된 현상이 원거리 광통신 시스템에 많은 문제점을 유발하게 되었다. 특히 편광의존손실(PDL)은 시스템의 BER과 신호 왜곡을 가중시켜 시스템 성능을 저하시킨다. 이러한 PDL을 시스템 상에서 보정하는 것은 매우 복잡하고 어렵기 때문에 광 부품 제조 단계에서 PDL을 작게 되도록 해야하며, 이를 위해 정확한 PDL을 측정이 요구된다. (중략)