• The korean journal of orthodontics
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• v.42 no.5
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• pp.249-254
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• 2012

Objective: To investigate the stem cell-like characteristics of human periodontal ligament (PDL) stromal cells outgrown from orthodontically extracted premolars and to evaluate the potential for myogenic differentiation. Methods: PDL stromal cells were obtained from extracted premolars by using the outgrowth method. Cell morphological features, self-replication capability, and the presence of cell-surface markers, along with osteogenic, adipogenic, and chondrogenic differentiation, were confirmed. In addition, myogenic differentiation was induced by the use of 5-aza-2'-deoxycytidine (5-Aza) for DNA demethylation. Results: PDL stromal cells showed growth patterns and morphological features similar to those of fibroblasts. In contrast, the proliferation rates of premolar PDL stromal cells were similar to those of bone marrow and adipogenic stem cells. PDL stromal cells expressed surface markers of human mesenchymal stem cells (i.e., CD90 and CD105), but not those of hematopoietic stem cells (i.e., CD31 and CD34). PDL stromal cells were differentiated into osteogenic, adipogenic, and chondrogenic lineages. Myotube structures were induced in PDL stromal cells after 5-Aza pretreatment, but not in the absence of 5-Aza pretreatment. Conclusions: PDL stromal cells isolated from extracted premolars can potentially be a good source of postnatal stem cells for oromaxillofacial regeneration in bone and muscle.

• The korean journal of orthodontics
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• v.22 no.1
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• pp.273-283
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• 1992

To find out the differences between periodontal ligament cells (PDL cells) and gingival fibroblast cells (GFB cells), alkaline phosphatase, a marker enzyme for osteoblast, was used to measure the activities and $^{45}CaCl_2$ isotope was used to find out cellular and release of $^{45}Ca$, a requisite for bone formation,. PDL cells and GFB cells from 1 to 5 passages were also measured in alkaline phosphatase activity assay. By the use of above methods, followings were concluded that the PDL cells and the GFB cells have characteristics that are different from each other. In that PDL cells showed large amount of calcium uptake and large amount of calcium release in initial stage, they seem to possess characteristics which are similar to osteoblast-like cells. 1. The PDL cells, in contrast to the gingival fibroblast, showed exceedingly high alkaline phosphatase activity which was highest at the second passage, decreasing thereon. But gingival fibroblasts cells showed no distinct differences in alkaline phosphatase activity as the passage were elapsed. 2. For both PDL cells and GF cells, the $^{45}Ca$ uptake was greatest at 2 hours period. The PDL cells showed higher measuring than GFB cells through out the whole time period. 3. Whereas the GFB cells showed slow increase of $^{45}Ca$ release as time relapsed, the PDL cells showed rapid increase of $^{45}Ca$ release.

• The korean journal of orthodontics
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• v.50 no.3
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• pp.188-196
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• 2020

Objective: Preservation of the periodontal ligament (PDL) is vital to the success of tooth autotransplantation (TAT). Increased PDL volumes and facilitated tooth extraction have been observed upon orthodontic preloading. However, it is unclear whether any changes occur in the expressions of bone biomolecules in the increased PDL volumes. This study aimed to determine the expressions of runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), receptor activator of nuclear factor kappa-B ligand (RANKL), and osteoprotegerin (OPG) in PDL upon preloading. Methods: Seventy-two premolars from 18 patients were randomly assigned to experimental groups that received a leveling force for 1, 2, or 4 weeks or to a control unloaded group. Following extraction, PDL volumes from 32 premolars of eight patients (21.0 ± 3.8 years) were evaluated using toluidine blue staining. The expressions of the biomolecules in the PDL from 40 premolars of ten patients (21.4 ± 4.0 years) were analyzed via immunoblotting. Results: The median percentage of stained PDL was significantly higher at 2 and 4 weeks after preloading than in the unloaded condition (p < 0.05). The median RUNX2 and ALP expression levels were significantly higher at 2 and 4 weeks after preloading than in the unloaded condition (p < 0.05), whereas the median RANKL/OPG ratios were significantly higher at 1 and 4 weeks after preloading (p < 0.05). Conclusions: Orthodontic preloading for 4 weeks enhances PDL volumes as well as the expressions of RUNX2, ALP and the RANKL/OPG ratio in the PDL, suggesting this loading period is suitable for successful TAT.

• Korean Journal of Plant Resources
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• v.35 no.2
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• pp.385-389
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• 2022

In this study, we measured the inhibitory activity of Pinus densiflora leaf (PDL) against excessive lipid accumulation in mouse preadipocyte, 3T3-L1 cells to investigate whether PDL exerts anti-obesity activity. Lipid accumulation and the protein level were measured using Oil red O staining assay and Western blot analysis, respectively. We observed that PDL inhibited excessive lipid accumulation and decreased the expression of CEBPα, PPARγ and perilipin-1 related to lipid accumulation in 3T3-L1 cells. Therefore, considering these results, PDL can be used as a potential agent for anti-obesity.

• Journal of Veterinary Clinics
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• v.37 no.2
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• pp.75-81
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• 2020

The objective of the present study was to evaluate the effectiveness of autoligation techniques for castrating healthy male small breed dogs. Forty dogs were divided into four groups, with 10 in each group, based on maturity and the surgical technique used: 1) immature dogs aged less than 1 year, with autoligation of the spermatic cord via a scrotal approach (SAL) as the surgical technique (SAL-IM); 2) mature dogs aged 1 year or older, with the same SAL surgical technique (SAL-M); 3) immature dogs aged less than 1 year, with double ligation of the spermatic cord with an absorbable suture via a prescrotal approach (PDL) as the surgical technique (PDL-IM); and 4) mature dogs aged 1 year or older, with the same PDL surgical technique (PDL-M). The effectiveness of the surgical technique was evaluated by comparing the operating time and complications between these four groups. The significant decreases in operating times were found in SAL-IM and SAL-M compared with those of PDL-IM and PDL-M (p < 0.01 and p < 0.01). Regardless of maturity, the SAL surgical technique reduced operating time by approximately 69.5% compared with the PDL surgical technique. When the complication severities were scored, the results showed no significant differences among the four group. The autoligation technique for castration in healthy male small breed dogs is considered to be effective because the operating time consuming is less than conventional techniques.

• Journal of the Korean Society for information Management
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• v.20 no.2
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• pp.177-198
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• 2003

The most significant part of this study is in developing an experimental medel of user-friendly PDL. This study proposes both theoretical (conceptual) and physical (operational) models. The theoretical model includes the analysis on various factors and the realtionsips among factors which have a serious impacts on the design, building, and managing of PDL. And the physical model shows the shows the detailed structure and process which could be useful for both PDL designers and managers. Also provided is the images of major user interfaces, of which a PDL would be developed on the basis of the proposed medel in near future.

• Journal of Periodontal and Implant Science
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• v.36 no.3
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• pp.783-796
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• 2006

The periodontium is a topographically complex organ consisting of epithelial tissue, soft and mineralized tissues. Structures comprising the periodontium include the gingiva, periodontal ligament (PDL) , cementum and the alveolar bone. The molecular mechanism of differentiation in PDL fibroblast cells remain unclear. Amino acid transporters play an important role in supplying nutrition to normal and cancer cells and for cell proliferation. Amino acid transport system L is a major nutrient transport system responsible for the Na+-independent transport of neutral amino acids including several essential amino acids. The system L is divided into two major subgroups, the L-type amino acid transporter 1 (LAT1) and the L-type amino acid transporter 2 (LAT2). In this study, the expression pattern of amino acid transport system L was, therefore, investigated in the differentiation of PDL fibroblast cells. To determine the expression level of amino acid transport system L participating in intracellular transport of amino acids in the differentiation of PDL fibroblast cells, it was examined by RT-PCR, observation of cell morphology, Alizaline red-S staining and uptake analysis after inducing experimental differentiation in PDL fibroblast cells isolated from mouse molar teeth. The results are as follows. 1. The LAT1 mRNA was expressed in the early stage of PDL fibroblast cell differentiation. This expression level was gradually reduced by differentiation- inducing time and it was not observed after the late stage. 2. The expression level of LAT2 mRNA was increased in time-dependent manner during differentiation induction of PDL fibroblast cells. 3. There was no changes in. the expression level of 4F2hc mRNA, the cofactor of LAT1 and LAT2, during differentiation of PDL fibroblast cells. 4. The expression level of ALP mRNA was gradually increased and the expression level of Col I mRNA was decreased during differentiation of PDL fibroblast cells. 5. The L-leucine transport was reduced by time from the early stage to the late stage in PDL fibroblast cell differentiation. As the results, it is considered that among neutral ammo acid transport system L in differentiation of PDL fibroblast cells, the LATl has a key role in cell proliferation in the early stage of cell differentiation and the LAT2 has an important role in the late stage of cell differentiation for providing cells with neutral amino acids including several essential amino acids.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.1-12
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• 2002

The periodontal ligament(PDL) is a unique tissue that is crucial for tooth function. However, little is known of the molecular mechanisms controlling PDL function. PDL-specific protein;PDLs22 had been previously identified as a novel protein isolated from cultured human PDL fibroblasts using subtraction hybridization between human gingival fibroblasts and PDL fibroblasts. The aim of this study was to examine the expression pattern and tissue localization of PDLs22 protein in embryonic and various postnatal stages of developing mouse using immunohistochemical staining. Embryos (E18) and postnatal (P1, P4, P5, P15, P18) were decapitated and the heads were fixed overnight in a freshly prepared solution of 4% paraformaldehyde. Some specimens were decalcified for $2{\sim}4$ weeks in a solution containing 10% of the disodium salt of ethylenediamine-tetraacetic acid (EDTA). Next, tissues were dehydrated, embedded in paraffin and sectioned serially at $6{\mu}m$ in thickness. Polyclonal antiserum raised against PDLs22 peptides, ISNKYLVKRQSRD, were made. The localization of PDLs22 in tissues was detected by polyclonal antibody against PDLs22 by means of immunohistochemical staining. The results were as follows; 1. Expression of PDLs22 protein was not detected in the tooth germ of bud and cap stage. 2. At the late bell stage and root formation stage, strong expression of PDLs22 protein was observed in developing tooth follicle, osteoblast-like cells, and subodontoblastic cells in the tooth pulp, but not in gingival fibroblasts, ameloblasts and odontoblasts of tooth germ 3. In erupted tooth, PDLs22 protein was intensely expressed in PDL and osteoblast-like cells of alveolar bone, but not in gingival fibroblasts, mature osteocytes and adjacent salivary glands. 4. In the developing alveolar bone and mid-palatal suture, expression of PDLs22 protein was seen in undifferentiated mesenchymal cells and osteoblast-like cells of developing mid-palatal suture, but not in mature osteocytes and chondrocytes. These results suggest that PDLs22 protein may play an important role in the differentiation of undifferentiated mesenchymal cells in the bone marrow and PDL cells, which can differentiate into multiple cell types including osteoblasts, cementoblasts, and PDL fibroblasts. However, more researches should be performed to gain a better understanding of the exact function of PDLs22 protein which related to the PDL cell differentiation.

• International Journal of Oral Biology
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• v.33 no.2
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• pp.51-58
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• 2008

A mutation of UNCL, an inner nuclear membrane RNAbinding protein, has been found to eliminate mechanotransduction in Drosophila. UNCL is expressed in human periodontal tissue including in periodontal ligament (PDL) fibroblasts. However, it is unclear how a mechanical stimulus is translated into cellular responses in PDL fibroblasts. The aim of this study was to evaluate the effect of UNCl on mechanical stress related genes in PDL fibroblasts in response to mechanical stress. The mRNA of TGF-$\beta$, COX-2, and MMP-2 was up-regulated after UNCL inactivation in PDL fibroblasts under the compression force. Under the tensile force, inactivation of UNCL decreased the expression of Biglycan, RANKL, MMP-2, and TIMP-2 mRNAs while it increased the expression of TIMP-1. p38-MAPK was expressed in PDL fibroblasts under compression forces whereas phospho-ERK1/2, p65-NFkB, and c-fos were expressed under tension forces. The expression and phosphorylation of the mechanical stress related genes, kinases, and transcription factors were changed according to the types of stress. Furthermore, most of them were regulated by the inactivation of UNCL. This suggests that UNCL is involved in the regulation of mechanical stress related genes through the signaling pathway in PDL fibroblasts.

• Journal of Periodontal and Implant Science
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• v.24 no.3
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• pp.572-580
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• 1994

The purpose of the present study was to evaluate the effect of platelet - derived growth factor(PDGF) - BB and insulin - like growth factor(IGF) - 1, Centella Asiatica, and Zea Mays L. on the mitogenic activity of PDL cells from healthy and RPP patients. Combination of PDGF - BB and IGF - 1, Centella Asiatica, and Zea Mays L. were treated on PDL cells and the mitogenic effects were meaured by quantitative assay of methyl - $^3H$ - thymidine incorporation during DNA synthesis. Combination of PDGF - BB and IGF - 1 enhenced the mitogenic effects of both healthy and RPP PDL cells, however, the effect was less pronounced on RPP PDL cells. In cases of Centella Asiatica and Zea Mays L., no mitogenic effect on healthy PDL cells could be noticed.