• Korean Journal of Materials Research
• /
• v.33 no.8
• /
• pp.323-329
• /
• 2023

There are many types of foam molding methods. The most commonly used methods are the pressure foaming method, in which foam resin is mixed with a foaming agent at high temperature and high pressure, and the normal pressure foaming method, which foams at high temperature without pressure. The polymer resins used for foaming have different viscosities. For foaming under normal pressure, they need to be designed and analyzed for optimal foaming conditions, to obtain resins with low melt-viscosity or a narrow optimal viscosity range. This study investigated how changes in viscosity, molding temperature, and cross-link foaming conditions affected the characteristics of the molded foam, prepared by blending rubber polymer with biodegradable resin. The morphologies of cross sections and the cell structures of the normal pressure foam were investigated by SEM analysis. Properties were also studied according to cross-link/foaming conditions and torque. Also, the correlation between foaming characteristics was studied by analyzing tensile strength and elongation, which are mechanical properties of foaming composites.

• BMB Reports
• /
• v.56 no.9
• /
• pp.496-501
• /
• 2023

Elongation of most bones occur at the growth plate through endochondral ossification in postnatal mammals. The maturation of chondrocyte is a crucial factor in longitudinal bone growth, which is regulated by a complex network of paracrine and endocrine signaling pathways. Here, we show that a phytochemical sulfuretin can stimulate hypertrophic chondrocyte differentiation in vitro and in vivo. We found that sulfuretin stabilized nuclear factor (erythroid-derived 2)-like 2 (Nrf2), stimulated its transcriptional activity, and induced expression of its target genes. Sulfuretin treatment resulted in an increase in body length of zebrafish larvae and induced the expression of chondrocyte markers. Consistently, a clinically available Nrf2 activator, dimethyl fumarate (DMF), induced the expression of hypertrophic chondrocyte markers and increased the body length of zebrafish. Importantly, we found that chondrocyte gene expression in cell culture and skeletal growth in zebrafish stimulated by sulfuretin were significantly abrogated by Nrf2 depletion, suggesting that such stimulatory effects of sulfuretin were dependent on Nrf2, at least in part. Taken together, these data show that sulfuretin has a potential use as supporting ingredients for enhancing bone growth.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.17 no.1
• /
• pp.241-246
• /
• 2003

Bambusae Caulis in Liquamen(BCL) has been used to relieve the cough and asthma, and remove the phlegm in traditional Oriental medicine. In recent years, it was studied for its antiinflammatory, antiallergenic, immune-modulating, and anticarcinogenic capabilities. This experiment was performed to evaluate the microarray profiles of CD genes in human mast cells before and after BCL treatment. The results are as follows: The expression of 51 of the genes studied was up-regulated in the Bel-treated group; they include the genes coding L apoferritin, beta-2-microglobulin, ferritin light polypeptide, CD63, monocyte chemotactic and activating fact, heme oxygenase 1, CD140a, integrin alpha M, colony stimulating factor 2 receptor, eukaryotic translation elongation factor, CD37, interleukin 18, NADH dehydrogenase 1 beta, CD48, 5-lipoxygenase activating protein, interleukin 4, ribosomal protein L5, GABA(A) receptor-associated protein, beta-tubulin, integrin beta 1, CD162, CD32, lymphotoxin beta, alpha-tublin, integrin alpha L, CD2, CD151, CD331, 90 kDa heat shock protein, CD59, CD3Z, microsomal glutathione S-transferase 2, CD33, CD162R, cyclophilinA, CD84, interleukin 9 receptor, interleukin 11, CD117, CD39-Like 2, and so forth. The expression of 7 of the genes studied was down-regulated in the BCL-treated group; they include the genes coding con, CD238, SCF, CD160, CD231, CD24, and CD130. Consequently, the treatment of BCL on the human mast cells increased the expression of 51 genes and decreased the expression of 7 genes. These data would provide a fundamental basis to the traditional applications of Bambusae Caulis in Liquamen.

• 한국생물공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.359-362
• /
• 2003

The recent development of methods for culturing hair follicles in vitro has proved an important tool to investigate many aspects of drug screening. Human hair follicle is composed of multiple types of cells, whose interactions regulate morphology and cycling-anagen, catagen, and telogen. Many investigators have tried to develop models to prolong of the period of hair elongation in vitro. However these are limited in submerged culture, which don't work due to the lack of cell-cell interactions which are abundant in vivo environment. So we applied dermal equivalent (DE) to culturing flair follicles to prolong hair growth period.

• Korean journal of applied entomology
• /
• v.22 no.2 s.55
• /
• pp.147-159
• /
• 1983

In general, herbicides have been classified according to selectivity, mobility. time of application, methods of application, mode of action and chemical property and structure. However, there was no generally accepted classification system for practical use in the field. The primary processes affected by the majority of herbicides are the growth process through cell elongation and/or cell division, the photosynthetic process specifically the light reaction, the oxidative phosphorylation and the integrity of the membrane systems. The usual approach in the study of the mechanism by which herbicides kill or inhibit the growth of plants is to initially determine the morphological phototoxicity systems, The mechanism by which a herbicide kills a plant or suppresses its development is actually the resultant effect of primary and secondary(or side) effects. In most instances, the death of the plant is due to the secondary effects. To induce the desired response, a herbicide must be able to gain entry into the plants and once inside, to be transported within the plant to its site(s) of activity in concentrations great enough. Obstacles to the entry and movement of herbicides in plants are generally classified by leaf and soil obstacles, translocation obstacles and biochemical obstacles, and these obstacles are also strongly influenced by plant species and by environmental factors such as light, temperature, rainfall and relative humidity. And hence, in most instances, results obtained from laboratory or greenhous vary from those of field experiment. Author attempted to classify herbicides from the field experiment using the two-dimensional ordination analysis to obtain practical information for selecting effective herbicides or to choose effective herbicide combinations for increasing herbicidal efficacy or reducing the chemical cost. Based on this two-dimensional diagram, desired herbicides or combinations were selected and further investigated for the interaction effects whether these combinations are synergistic, additive or antagonistic. From the results, it was concluded that these new approach could possibly be give more comprehensive informations about effective use of herbicide than any other systems.

• Korean Journal of Food Science and Technology
• /
• v.8 no.1
• /
• pp.47-52
• /
• 1976

Growth inhibition and morphological alteration of Bacillus megaterium NRRL B-1368 in aflatoxin-containing TGY liquid media and its growth restoration in normal media were investigated. Crude aflatoxins $(B_1\;22.7%,\;B_2\;1.6%,\;G_1\;3.6\;%\;and\;G_2\;0.2%)$ at concentrations of more than $20{\mu}g/ml$ inhibited the growth of the microorganism and prevented the formation of septum, resulting in abnormal elongation and disturbance of cell division. The aberrant cells, however, grew normally by septum formation and cell division upon returning to aflatoxin-free culture media. It was, therefore, assumed that aflatoxin affects the function of mesosome related to septum formation in bacteria.

• Biomedical Science Letters
• /
• v.12 no.2
• /
• pp.119-125
• /
• 2006

In relation to the tissue engineering, the cellular responses to the morphology of the scaffold surface are interesting topics. Human ligament fibroblasts (HLFs) were cultured on the micrpatterned silicone substrates subjected to cyclic stretch to simulate ligament motion. Groove and ridge width of silicone substrates was 10/50, 20/50, 20/10, and 20/20 ${\mu}m$ (groove/ridge ${\mu}m$) with a depth of $3{\mu}m$. Strain was applied over two days for 4 hours per day with a frequency of 0.5 Hz with the magnitudes of 4 or 8%. The purpose of this study was to evaluate ligament fibroblast alignment and cellular responses in relation to the pattern of microgrooved surface and stretching magnitude. Ligament fibroblasts in the microgrooved surface were elongated and aligned parallel to the microgrooves under no stretch. Uniaxial cyclic stretch induced cellular activities and their orientation rise in cellular response and the cells showed alignment and elongation perpendicular to the direction of the stretch. Biochemical analyses showed that the best cellular response was found on the $20/50{\mu}m$ under 8% stretch. The surface morphology and mechanical stretching were found to contribute to increase of proliferation, collagen production.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.3
• /
• pp.510-519
• /
• 2001

The tensile and fracture toughness tests have been conducted to investigate the degradations of mechanical properties induced mainly by neutron irradiations in Zr-2.5Nb CANDU pressure tube materials operated in Wolsung Unit-1. the tests were performed at room, 150, 200, 250, 300 $\^{C}$ for the irradiated and unirradiated specimens in hot cell. The specimens were directly machined from the tube retaining original curvature using specially designed electric discharge machine(EDM). From the tensile tests of the irradiated specimens, it was found that tensile strength was increased and total elongation was decreased compared to those of the unirradiated ones. The active voltages in the fracture toughness tests for the irradiated showed the discontinuous abrupt increases caused by crack jumping in lower temperature. In the crack resistance curves we found the stable crack growth in the unirradiated, whereas the unstable and three crack growth stages in the irradiated specimens due to the accumulated irradiation defects. The various fracture characteristic values in the irradiated are remarkably lower than those of the unirradiated. Through the fractography, we found in the irradiated that smaller dimple and shorter fissures than the unirradiated, and that the fractured surface had three regions that were flat, transition and slant/shear area. These can explain the difference in the crack growth characteristic values of the irradiated and the unirradiated ones.

• The Korean Journal of Physiology and Pharmacology
• /
• v.4 no.2
• /
• pp.81-90
• /
• 2000

The types of $K^+$ channel which determine the pattern of spontaneous action potential (SAP) were investigated using whole-cell variation of patch clamp techniques under current- and voltage-clamp recording conditions in rat clonal pituitary $GH_3$ cells. Heterogeneous pattern of SAP activities was changed into more regular mode with elongation of activity duration and afterhyperpolarization by treatment of TEA (10 mM). Under this condition, exposure of the class III antiarrhythmic agent E-4031 $(5\;{\mu}M)$ to $GH_3$ cells hardly affected SAP activities. On the other hand, the main $GH_3$ stimulator thyrotropin-releasing hormone (TRH) still produced its dual effects (transient hyperpolarization and later increase in SAP frequency) in the presence of TEA. However, addition of $BaCl_2$ (2 mM) in the presence of TEA completely blocked SAP repolarization process and produced membrane depolarization in all tested cells. This effect was observed even in TEA-untreated cells and was not mimicked by higher concentration of TEA (30 mM). Also this barium-induced membrane depolarization effect was still observed after L-type $Ca^{2+}$ channel was blocked by nicardipine $(10\;{\mu}M).$ These results suggest that barium-sensitive current is important in SAP repolarization process and barium itself may have some depolarizing effect in $GH_3$ cells.

• The Korean Journal of Physiology and Pharmacology
• /
• v.24 no.4
• /
• pp.299-310
• /
• 2020

Alzheimer's disease (AD) is a multi-faceted neurodegenerative disease. Thus, current therapeutic strategies require multitarget-drug combinations to treat or prevent the disease. At the present time, single drugs have proven to be inadequate in terms of addressing the multifactorial pathology of AD, and multitarget-directed drug design has not been successful. Based on these points of views, it is judged that combinatorial drug therapies that target several pathogenic factors may offer more attractive therapeutic options. Thus, we explored that the combination therapy with lower doses of cilostazol and aripiprazole with add-on donepezil (CAD) might have potential in the pathogenesis of AD. In the present study, we found the superior efficacies of donepezil add-on with combinatorial mixture of cilostazol plus aripiprazole in modulation of expression of AD-relevant genes: Aβ accumulation, GSK-3β, P300, acetylated tau, phosphorylated-tau levels, and activation of α-secretase/ADAM 10 through SIRT1 activation in the N2a Swe cells expressing human APP Swedish mutation (N2a Swe cells). We also assessed that CAD synergistically raised acetylcholine release and choline acetyltransferase (CHAT) expression that were declined by increased β-amyloid level in the activated N2a Swe cells. Consequently, CAD treatment synergistically increased neurite elongation and improved cell viability through activations of PI3K, BDNF, β-catenin and α7-nicotinic cholinergic receptors in neuronal cells in the presence of Aβ_1-42. This work endorses the possibility for efficient treatment of AD by supporting the synergistic therapeutic potential of donepezil add-on therapy in combination with lower doses of cilostazol and aripiprazole.