• Proceedings of the Zoological Society Korea Conference
• /
• 1996.10a
• /
• pp.224.2-224
• /
• 1996

No Abstract, See Full Text

• Journal of Integrative Natural Science
• /
• v.9 no.3
• /
• pp.171-176
• /
• 2016

Rap1 is a key regulator of cell adhesion and migration. Although increasing evidence indicates that the Rap1 signaling pathway is involved in the process of bone remodeling, the mechanism by which Rap1 regulates osteoblastic differentiation and cell adhesion remains unknown. Here, we investigated the morphological characteristics and osteoblastic differentiation of cells expressing constitutively activated form of Rap1A (Rap1ACA) or Rap1 GTPase activating protein Rap1GAP and found that activated Rap1 induces osteoblastic differentiation and cell adhesion as well as cell spreading. When osteoblastic differentiation was induced, Rap1ACA cells showed considerably higher levels of calcium deposits than the wild-type and Rap1GAP-overexpressing cells did. Rap1ACA cells showed increased spreading and size, as well as strong cell adhesion and significantly decreased growth rates. F-actin staining using phalloidin revealed several thin thread-like filopodia around the protrusions in Rap1ACA cells, which possibly contribute to the increased cell adhesion.

• BMB Reports
• /
• v.28 no.4
• /
• pp.316-322
• /
• 1995

The GTPase activating protein (GAP) can function both as a negative regulator and an effector of $p21^{ras}$. Overexpression of GAP in NIH-3T3 cells has been shown to inhibit transformation by ms or src. To investigate the function of GAP in a differentiative system, we overexpressed this protein in the nerve growth factor (NGF)-responsive PC12 cell line. Two-fold overexpression of GAP caused a delay of several days in the onset of NGF- but not FGF-induced neuronal differentiation of PC12 cells. However, the NGF-induced activation or tyrosine phosphorylation of upstream (Trk, PLC-${\gamma}1$, SHC) and downstream (B-Raf and $p44^{mapk/erk1}$) components of $p21^{ras}$, signalling cascade was not altered by GAP overexpression. Therefore, the change of phenotype induced by GAP was probably not due to GAP functioning as a negative regulator of $p21^{ras}$. Rather, we found that NGF-induced tyrosine phosphorylation of SNT, a specific target of neurotrophin-induced tyrosine kinase activity, was inhibited by GAP overexpression. SNT is thought to function upstream or independent of $p21^{ras}$. Thus in PC12 cells, overexpressed GAP may control the rate of neuronal differentiation through a pathway involving SNT rather than the $p21^{ras}$ signalling pathway.

• Journal of Plant Biology
• /
• v.33 no.1
• /
• pp.41-48
• /
• 1990

Changes in polamine titers during shoot differentiation in Cymbidium sp. (Jungfrau) protocorms were studied in order to investigate the mechanism of shoot differentiation by using auxin-inhibitors(PCIB, TIBA), hormones(GA3, ABA, BA), and phenolic compounds (2,4-dichlorophenol, catechol). The shoot differentiation and propagation of protocorms were promoted by PCIB or 2,4-dichlorophenol, and the growth of differentiated shoot were promoted by TIBA or catechol. In BA-treated protocorms, white or brown protocorms were observed. Putrescine was the most abundant polyamine during the propagation and differentiation processes. As compared with putrescine, spermidine did not show significant changes and spermine was not detected at all. Putrescine titers decreased after a temporary increase, and then again increased in the presence of GA3, ABA, 2,4-dichlorophenol, and then again increased in the presence of GA3, ABA, 2,4-dichlorophenol, catechol, or PCIB. But, in BA-treated protocorms, putrescine level was much lower than spermidine.

• Journal of dental hygiene science
• /
• v.12 no.6
• /
• pp.689-695
• /
• 2012

The aim of this study was to elucidate the effects of concentrated growth factors (CGFs) on human gingival fibroblasts in vitro. Blood was collected from three male volunteers (average age 27 years). CGFs were prepared using standard protocols. The CGF exudates were collected at the following culture time points: 1, 7, 14, and 21 days. The levels of platelet-derived growth factor BB (PDGF-BB) and transforming growth factor ${\beta}1$ (TGF-${\beta}1$) in CGFs were quantified. The CGF exudates were then used to culture human gingival fibroblasts. The biologic characteristics of these fibroblasts were analyzed in vitro for 21 days. Platelet-rich plasma released the highest amounts of TGF-${\beta}1$ and PDGF-BB on the first day. The level of TGF-${\beta}1$ had decreased slightly by day 7, although the difference compared to levels at day 1 was not statistically significant. However, by days 14 and 21, levels of TGF-${\beta}1$ had dropped significantly compared to day 1 levels. The levels of PDGF-BB at days 7, 14, and 21 did not differ significantly from that measured on day 1. CGFs maintained the release of autologous growth factors for a reasonable period of time (7 days for TGF-${\beta}1$ and 21 days for PDGF-BB). Gingival fibroblasts treated with CGF exudates collected at day 14 reached peak viability and synthesized type I collagen. Furthermore, the CGF exudates exerted positive effects on the proliferation and differentiation of these cells at days 1, 7, 14, and 21. The findings of this study suggest that treatment with CGFs represents a promising method of enhancing mucosal healing following surgical procedures.

• Korea Journal of Hospital Management
• /
• v.4 no.1
• /
• pp.129-146
• /
• 1999

The overall objective of this article is to identify the strategic type of Korean hospitals in terms of Porter's framework and to examine differences in performance of the hospitals across strategic types. A survey was conducted through structured questionnaire for 739 hospitals in Korea and the data from 120 hospitals were utilized in the final analysis. Study results indicate that the most frequently used strategy was 'stuck-in-the-middle strategy'(26.7%), followed by 'focused cost leadership strategy'(24.0%), 'focused differentiation strategy'(20.8%), 'cost leadership strategy'(15.8%), and 'differentiation strategy'(13.7%). Overall, 'focused differentiation strategy' showed superior performance in terms of profitability of services, ability to retain patients and growth in revenue, while 'differentiation strategy' produced relatively low performance in general. Implications of these findings are also discussed.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.20 no.1
• /
• pp.31-41
• /
• 2004

The osseointegration in implant therapy is achieved following general wound healing mechanism. Platelet play a major role in wound healing process. In addition to blood clot formation, they secrete many growth factors which regulate the attachment, proliferation and differentiation of nearly all cell types. The use of these growth factors is now known to be very effective methods to improve the cellular activity. Platelet-rich plasma which is made with the newly developed technique concentrating platelets 3-folds or more is also proven to be very effective method to stimulate and accelerate the healing of bone and soft tissue. Previous study proved that platelet-rich plasma enhanced the cellular attachment by inducing fibronectin, vitronectin from osteoblast. So, this study was aimed to investigate the effect of platelet-rich plasma on the cellular proliferation and differentiation in vitro. The effect on the proliferation was evaluated by MTT assay. To evaluate autocrine and paracrine effect, conditioned medium was made and compared. By measuring alkaline phosphatase activity, the effect on the cellular differentiation was evaluated. The results were as following: The cellular proliferation of osteoblast cell line increased depending on the concentration of platelet-rich plasma and conditioned medium. The alkaline phosphatase activity increased depending on the concentration of platelet-rich plasma and conditioned medium. These findings imply that platelet-rich plasma enhance the cellular proliferation and differentiation and maximize the cellular activity by using the autocrine and paracrine effect.

• Journal of the Economic Geographical Society of Korea
• /
• v.8 no.2
• /
• pp.285-299
• /
• 2005

The economic reform in China since 1978 has been increasingly sped up and deepened. The recent development of private enterprises, especially, has significant economic and political implications, whereas its regional differentiation has considerable impacts on both the development potential of certain regions and overall regional growth pattern. This study aims to understand the regional pattern of private enterprise growth as well as the institutional change which has structured the growth process. The development of private enterprises turned out to be closely tied to the marketization strategy of dual-track system and policy needs to reduce the unemployment level in both urban and 겨ral China. The regional pattern of the private enterprise growth can be characterized as ever-increasing spatial differentiation. Based on the basic statistical analysis results, it is argued that the private enterprise growth is closed related with the marketization level of the regional economy. Therefore, the strategy of developing private sector will be more important in shaping the regional development path as well as potential.

• Journal of Periodontal and Implant Science
• /
• v.36 no.4
• /
• pp.839-847
• /
• 2006

The aim of this study is to monitor reporter gene expression under osteocalcin gene promoter, using a real-time molecular imaging system, as tool to investigate osteoblast differentiation. The promoter region of mouse osteocalcin gene 2 (mOG2), the best-characterized osteoblast-specific gene, was inserted in promoterless luciferase reporter vector. Expression of reporter gene was confirmed and relationship between the reporter gene expression and osteoblastic differentiation was evaluated. Gene expression according to osteoblstic differentiation on biomaterials, utilizing a real-time molecular imaging system, was monitored. Luciferase was expressed at the only cells transduced with pGL4/mOGP and the level of expression was statistically higher at cells cultured in mineralization medium than cells in growth medium. CCCD camera detected the luciferase expression and was visible differentiation-dependent intensity of luminescence. The cells produced osteocalcin with time-dependent increment in BMP-2 treated cells and there was difference between BMP-2 treated cells and untreated cells at 14days. There was difference at the level of luciferase expression under pGL4/mOGP between BMP-2 treated cells and untreated cells at 3days. CCCD camera detected the luciferase expression at cells transduced with pGL4/mOGP on Ti disc and was visible differentiation-dependent intensity of luminescence This study shows that 1) expression of luciferase is regulated by the mouse OC promoter, 2) the CCCD detection system is a reliable quantitative gene detection tool for the osteoblast differentiation, 3) the dynamics of mouse OC promoter regulation during osteoblast differentiation is achieved in real time and quantitatively on biomaterial. The present system is a very reliable system for monitoring of osteoblast differentiation in real time and may be used for monitoring the effects of growth factors, drug, cytokines and biomaterials on osteoblast differentiation in animal.

• Animal Bioscience
• /
• v.35 no.7
• /
• pp.989-998
• /
• 2022

Objective: This study investigated the effects of intrauterine growth restriction (IUGR) during late pregnancy on the cell growth, proliferation, and differentiation in ovine fetal thymuses. Methods: Eighteen time-mated Mongolian ewes with singleton fetuses were allocated to three groups at d 90 of pregnancy: restricted group 1 (RG1, 0.18 MJ ME/body weight [BW]^0.75/d, n = 6), restricted group 2 (RG2, 0.33 MJ ME/BW^0.75/d, n = 6) and control group (CG, ad libitum, 0.67 MJ ME/BW^0.75/d, n = 6). Fetuses were recovered at slaughter on d 140. Results: The G0/G1 phase cell number in fetal thymus of the RG1 group was increased but the proliferation index and the expression of proliferating cell nuclear antigen (PCNA) were reduced compared with the CG group (p<0.05). Fetuses in the RG1 group exhibited decreased growth hormone receptor (GHR), insulin-like growth factor 2 receptor (IGF-2R), and their mRNA expressions (p<0.05). For the RG2 fetuses, there were no differences in the proliferation index and PCNA expression (p>0.05), but growth hormone (GH) and the mRNA expression of GHR were lower than those of the CG group (p<0.05). The thymic mRNA expressions of cyclin-dependent protein kinases (CDKs including CDK1, CDK2, and CDK4), CCNE, E2-factors (E2F1, E2F2, and E2F5) were reduced in the RG1 and RG2 groups (p<0.05), and decreased mRNA expressions of E2F4, CCNA, CCNB, and CCND were occurred in the RG1 fetuses (p<0.05). The decreased E-cadherin (E-cad) as a marker for epithelial-mesenchymal transition (EMT) was found in the RG1 and RG2 groups (p<0.05), but the OB-cadherin which is a marker for activated fibroblasts was increased in fetal thymus of the RG1 group (p<0.05). Conclusion: These results indicate that weakened GH/IGF signaling system repressed the cell cycle progression in G0/G1 phase in IUGR fetal thymus, but the switch from reduced E-cad to increased OB-cadherin suggests that transdifferentiation process of EMT associated with fibrogenesis was strengthened. The impaired cell growth, retarded proliferation and modified differentiation were responsible for impaired maturation of IUGR fetal thymus.