• Korean Journal of Microbiology
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• v.12 no.1
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• pp.31-36
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• 1974

Four strains of yeasts were chosen from those isolated previously, and a strain from 160 isolates collected in this year were examined for the treatment of pulp waste liquor. Experiments about optimum nutrient condition, composition of cells, and reduction of B.O.D. on the "S" pulp industry waste liquor were performed with 5 strains. 1. The isolates(strain 112) was identified as Candida utilis. 2. The optium concentration of 4 components of nutrients were ($NH_4$)$SO_2$lg/l, yeast extract 70mg/l, $KH_2PO_4$ 300mg/l, and $MgSO_4{\ddot}7H_2O$ 500mg/l. 3. Specific growth ratio of Candida utilis KYRI 112 was 0.48/hr at optimum nutrient media and the yield was 0.45%(V/V). 4. Endomycopsis capsularis KYRI 613 contained more crude protein than the most of commercial yeasts. 5. The B.O.D. of waste liquor was reduced ro 20% of its value by the culture.e culture.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2010.04a
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• pp.7-7
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• 2010

Flotation deinking is a common practice for removing ink from recovered paper, and it is becoming a key process in many recycling paper mills. Flotation deinking was successfully introduced to the paper recycling industry in the 1980s, and its applications in wax removal, stickies control, and fiber fractionation have attracted great research interest. A successful flotation process has three major efficient subprocesses: the detachment of the ink particles from the fibers, the effective adhesion of the ink particles onto air bubble surfaces, and the removal of froth and ink particles from flotation cells. Surfactants can affect these subprocesses either positively or negatively. To understand how a surfactant can positively and negatively affect the flotation deinking process, the basic chemistry of surfactant in solution should be discussed.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.3
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• pp.275-287
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• 2010

Deep caries may induce pulpitis and the pulpal tissue interacts with microbial invasion. The immune response to protect the pulpal tissue can be mediated by cellular signal molecules produced by the pulpal cells. The understanding of these processes is important to find future therapeutic method for the diseased pulp. The pulp tissue from sound teeth was set as control group (n=30) and the pulp tissue from decayed teeth was set as test group (n=30). Total RNA was extracted from the pulp of each group and it was used for cDNA microarray and reverse transcriptase-polymerase chain reaction(RT-PCR). The expression of TGF-${\beta}1$ was studied by immunohistochemistry. The results were as follows: 1. cDNA microarray analysis identified 520 genes with 6-fold or greater difference in expression level with 143 genes more abundant in health and 377 genes more abundant in disease. 2. The RT-PCR analysis was done for randomly selected 14 genes and the results supported the result of cDNA microarray assay. 3. TGF-${\beta}1$ was highly expressed in the carious pulp and it was found in odontoblast by immunohistochemistry. In conclusion, many cytokines were found to be significantly changed their expression in the diseased pulp(/M/>1.6).

• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.17.1-17.9
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• 2021

Objectives: In recent in vitro study, it was reported that osteostatin (OST) has an odontogenic effect and synergistic effect with mineral trioxide aggregate (MTA) in human dental pulp cells. Therefore, the aim of this study was to evaluate whether OST has a synergistic effect with MTA on hard tissue formation in vivo. Materials and Methods: Thirty-two maxillary molars of Spraque-Dawley rats were used in this study. An occlusal cavity was prepared and the exposed pulps were randomly divided into 3 groups: group 1 (control; ProRoot MTA), group 2 (OST 100 μM + ProRoot MTA), group 3 (OST 10 mM + ProRoot MTA). Exposed pulps were capped with each material and cavities were restored with resin modified glass ionomer. The animals were sacrificed after 4 weeks. All harvested teeth were scanned with micro-computed tomography (CT). The samples were prepared and hard tissue formation was evaluated histologically. For immunohistochemical analysis, the specimens were sectioned and incubated with primary antibodies against dentin sialoprotein (DSP). Results: In the micro-CT analysis, it is revealed that OST with ProRoot MTA groups showed more mineralized bridge than the control (p < 0.05). In the H&E staining, it is showed that more quantity of the mineralized dentin bridge was formed in the OST with ProRoot MTA group compared to the control (p < 0.05). In all groups, DSP was expressed in newly formed reparative dentin area. Conclusions: OST can be a supplementary pulp capping material when used with MTA to make synergistic effect in hard tissue formation.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.2
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• pp.93-99
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• 2019

Telomeres are known as a specialized region in the end of chromosomes to protect DNA destruction, but their lengths are shortened by repetition of cell division. This telomere shortening can be preserved or be elongated by telomerase and TERT expression. Although a certain condition in the cells may affect to the cellular and molecular characteristics, the effect of differentiation induction to telomere length and telomerase activity in mesenchymal stem cells (MSCs) has been less studied. Therefore, the present study aimed to uncover periodical alterations of telomere length, telomerase activity and TERT expression in the dental pulp-derived MSCs (DP-MSCs) under condition of differentiation inductions into adipocytes and osteoblasts on a weekly basis up to 3 weeks. Shortening of telomere was significantly (p < 0.05) identified from early-middle stages of both differentiations in comparison with undifferentiated DP-MSCs by non-radioactive chemiluminescent assay and qRT-PCR method. Telomere length in undifferentiated DP-MSCs was 10.5 kb, but the late stage of differentiated DP-MSCs which can be regarded as the adult somatic cell exhibited 8.1-8.6 kb. Furthermore, the relative-quantitative telomerase repeat amplification protocol or western blotting presented significant (p < 0.05) decrease of telomerase activity since early stages of differentiations or TERT expression from middle stages of differentiations than undifferentiated state, respectively. Based on these results, it is supposed that shortened telomere length in differentiated DP-MSCs was remained along with prolonged differentiation durations, possibly due to weakened telomerase activity and TERT expression. We expect that the present study contributes on understanding differentiation mechanism of MSCs, and provides standardizing therapeutic strategies in clinical application of MSCs in the animal biotechnology.

• Restorative Dentistry and Endodontics
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• v.36 no.5
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• pp.397-408
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• 2011

Objectives: This study investigated changes in gene expressions concerning of differentiation, proliferation, mineralization and inflammation using Human-8 expression bead arrays when white Mineral Trioxide Aggregate and calcium hydroxide-containing cement were applied in vitro to human dental pulp cells (HDPCs). Materials and Methods: wMTA (white ProRoot MTA, Dentsply) and Dycal (Dentsply Caulk) in a Teflon tube (inner diameter 10 mm, height 1 mm) were applied to HDPCs. Empty tube-applied HDPCs were used as negative control. Total RNA was extracted at 3, 6, 9 and 24 hr after wMTA and Dycal application. The results of microarray were confirmed by reverse transcriptase polymerase chain reaction. Results: Out of the 24,546 genes, 43 genes (e.g., BMP2, FOSB, THBS1, EDN1, IL11, COL10A1, TUFT1, HMOX1) were up-regulated greater than two-fold and 25 genes (e.g., SMAD6, TIMP2, DCN, SOCS2, CEBPD, KIAA1199) were down-regulated below 50% by wMTA. Two hundred thirty nine genes (e.g., BMP2, BMP6, SMAD6, IL11, FOS, VEGFA, PlGF, HMOX1, SOCS2, CEBPD, KIAA1199) were up-regulated greater than two-fold and 358 genes (e.g., EDN1, FGF) were down-regulated below 50% by Dycal. Conclusions: Both wMTA and Dycal induced changes in gene expressions related with differentiation and proliferation of pulp cells. wMTA induced changes in gene expressions related with mineralization, and Dycal induced those related with angiogenesis. The genes related with inflammation were more expressed by Dycal than by wMTA. It was confirmed that both wMTA and Dycal were able to induce gene expression changes concerned with the pulp repair in different ways.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.538-548
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• 1995

Calcium hydroxide has been used not only as pulp capping and pulpotomy agents in the operative dentistry, but dressing and temporary filling materials in root canal treatment. Calcium hydroxide was known to stimulate odontoblast to produce new reparative dentin and to eliminate microorganims effectively in the infected root canals. The purpose of this study was to evaluate the effect of calcium hydroxide solution on cultured L929 cells and its antibacterial effect on several streptococci. Calcium hydroxide solution (0.121g/100ml) was added to L929 cells and cell viability was measured using 3-(4,5-dimethylthiazol-2-yl) -2,5-dimethyltetrazolium bromide (MTT) and neutral red (NR) dye. Calcium hydroxide solution (20, 40, 60, 80, 100 and $150{\mu}l$) was added to L929 cells in 96-well microplates for 1, 4 and 24 hours respectively. Cell viability was gradually decreased when the volume and exposure time of calcium hydroxide solution were increased. When $150{\mu}l$ of calcium hydroxide was applied to L929 cells for 24 hours, there was more than fifty percent reduction of cell viability. Calcium hydroxide solution (20g/100ml) showed antibacterial effect against S. uberis, S. intermedius and S. mitis after thirty-second exposure. But 0.121g/100ml concentration of cacium hydroxide solution exhibited no antibacterial effect on six streptococci after one-hour exposure.

• International Journal of Stem Cells
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• v.16 no.2
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• pp.180-190
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• 2023

Background and Objectives: Regenerative endodontic procedures (REPs) are a research hotspot in the endodontic field. One of the biggest problems of REPs is that it is difficult to realize regeneration of pulp-dentin complex and functional reconstruction. The reason is still not clear. We hypothesize that the migration may be different in different dental stem cells. Periodontal ligament stem cells (PDLSCs) may migrate faster than stem cells of apical papilla (SCAPs), differentiating into cementum-like tissue, bone-like tissue and periodontal ligament-like tissue and, finally affecting the outcomes of REPs. Hence, this study aimed to explore the mechanism that regulates the migration of PDLSCs. Methods and Results: After isolating and culturing PDLSCs and SCAPs from human third molars, we compared the migration of PDLSCs and SCAPs. Then we investigated the role of SDF-1𝛼-CXCR4/CXCR7 axis in PDLSC migration. We further investigated the impact of Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) on PDLSC migration and the potential mechanism. PDLSCs showed better migration under both noninflammatory and inflammatory conditions than SCAPs. SDF-1𝛼 can promote the migration of PDLSCs by elevating the expression of CXCR4 and CXCR7, increasing the interaction between them, promoting expression of 𝛽-arrestin1 and activating the ERK signaling pathway. P. gingivalis LPS can promote the migration of PDLSCs toward SDF-1𝛼 through increasing the expression of CXCR4 via the NF-𝜅B signaling pathway, promoting the expression of 𝛽-arrestin1, and activating the ERK signaling pathway. Conclusions: This study helped elucidate the potential reason for the difficulty in forming pulp-dentin complex.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.2
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• pp.55-62
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• 2013

Bone tissue engineering is one of the important therapeutic approaches to the regeneration of bones in the entire field of regeneration medicine. Mesenchymal stem cells (MSCs) are actively discussed as material for bone tissue engineering due to their ability to differentiate into autologous bone. MSCs are able to differentiate into different lineages: osteo/odontogenic, adipogenic, and neurogenic. The tissue of origin for MSCs defines them as bone marrow-derived stem cells, adipose tissue-derived stem cells, and, among many others, dental stem cells. According to the tissue of origin, DSCs are further stratified into dental pulp stem cells, periodontal ligament stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, and dental papilla cells. There are numerous in vitro/in vivo reports suggesting successful mineralization potential or osteo/odontogenic ability of MSCs. Still, there is further need for the optimization of MSCs-based tissue engineering methods, and the introduction of genes related to osteo/odontogenic differentiation into MSCs might aid in the process. In this review, articles that reported enhanced osteo/odontogenic differentiation with gene introduction into MSCs will be discussed to provide a background for successful bone tissue engineering using MSCs with artificially introduced genes.

• Journal of Periodontal and Implant Science
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• v.41 no.4
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• pp.192-200
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• 2011

Purpose: The aim of this study is to compare the gene expression profile in mesenchymal stem cells derived from dental tissues and bone marrow for characterization of dental stem cells. Methods: We employed GeneChip analysis to the expression levels of approximately 32,321 kinds of transcripts in 5 samples of bone-marrow-derived mesenchymal stem cells (BMSCs) (n=1), periodontal ligament stem cells (PDLSCs) (n=2), and dental pulp stem cells (DPSCs) (n=2). Each cell was sorted by a FACS Vantage Sorter using immunocytochemical staining of the early mesenchymal stem cell surface marker STRO-1 before the microarray analysis. Results: We identified 379 up-regulated and 133 down-regulated transcripts in BMSCs, 68 up-regulated and 64 down-regulated transcripts in PDLSCs, and 218 up-regulated and 231 down-regulated transcripts in DPSCs. In addition, anatomical structure development and anatomical structure morphogenesis gene ontology (GO) terms were over-represented in all three different mesenchymal stem cells and GO terms related to blood vessels, and neurons were over-represented only in DPSCs. Conclusions: This study demonstrated the genome-wide gene expression patterns of STRO-$1^+$ mesenchymal stem cells derived from dental tissues and bone marrow. The differences among the expression profiles of BMSCs, PDLSCs, and DPSCs were shown, and 999 candidate genes were found to be definitely up- or down-regulated. In addition, GOstat analyses of regulated gene products provided over-represented GO classes. These data provide a first step for discovering molecules key to the characteristics of dental stem cells.