• Structural Engineering and Mechanics
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• v.2 no.3
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• pp.257-267
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• 1994

Motions of an unsymmetric rigid body on a rigid floor subjected to earthquake excitations with special attention to coefficient of friction are investigated. Motions of a body in a plane are classified (Ishiyama 1980) into six types, i.e. (1) rest, (2) slide, (3) rotation, (4) slide rotation, (5) translation jump, (6) rotation jump. Based upon the theoretical and experimental research work special attention is paid to the sliding of a body. The equations of motions and the behavior of coefficient of friction in the time of floor excitation are studied. One of the features of this investigation is the introduction and estimation of the "time dependent" coefficient of friction. It has been established that the constant kinetic coefficient of friction $${\mu}(kin){\sim_\sim}0.8{\mu}(stat)$$ does not give the appropriate results. The method for the estimation of the friction coefficient variation during the time is given.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.722-725
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• 1999

Filamentation-suppressed recombinant Escherichia coli strain harboring the Alcaligenes latus polyhydroxyalkanoate (PHA) biosynthesis genes and the E. coli ftsZ gene was constructed and cultivated for the production of poly(3-hydroxybutyrate) [P(3HB)] with high concentration and high content. By the pH-stat fed-batch culture of this recombinant E. coli strain XL1-Blue(pJC5), the final cell concentration and P(3HB) concentration obtained in 44.25h were 172.2g cell dry weight/l and 141.9g P(3HB)/l, respectively, resulting in productivity of 3.21g P(3HB)/l-h. More importantly, the P(3HB) content obtained was 82.4 wt %, which was significantly higher than that obtained with the recombinant E. coli harboring only the PHA biosynthesis genes.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.268-273
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• 1990

In order to elucidate the acid tolerance mechanism of Clostridium acetobutylicum against organic acid, the maintenance energy with added butyrate at different pH was determined. Maintenance coeffecient in acidogenic chemostat was higher at pH 6.5 than at pH 5.5 showing that this organism is an acidophile. The addition of butyrate at pH 5.5 and different dilution rate caused linear decrease of the cell concentration though $Y_{ATP}$ did not decrease with increasing undissociated organic acid. $Y_{ATP}$ decreased by increasing the concentration of undissociated organic acid at pH 5.0 by the addition of butyrate. From these results it is hypothesized that the ATP conaumption for pH stat of acidophile C. acetobutylicum is increased at the circumstance with over 30mM of undissociated organic acid.cid.

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.381-384
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• 1992

The hydrolytic susceptibility of large unilamellar vesicle (LUV) toward cabbage phospholipase D (PLD) was studied. The activity of PLD was determined by pH stat titration method. Using phosphatidylcholine LUV as substrate a pH optimum of 6.96 was observed. For maximal activity the optimal temperature of $31^{\circ}C$ and 10 mM of Ca2+ were required. The apparent Km value estimated was 2.5 mM. The hydrolytic activity of PLD toward PC LUV was somewhat high despite the absence of activator in assay system and this high susceptibility of PC LUV may be attributed to the structural properties of LUV. The effect of amphiphatic substances such as dicetyl phosphate and phosphatidic acid on the enzyme activity were also examined in mixed LUVs.

• BMB Reports
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• v.52 no.3
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• pp.214-219
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• 2019

The role of tumor-proximal factors in tumor plasticity during chemoresistance and metastasis following chemotherapy is well studied. However, the role of endothelial cell (EC) derived paracrine factors in tumor plasticity, their effect on chemotherapeutic outcome, and the mechanism by which these paracrine factors modulate the tumor microenvironment are not well understood. In this study, we report a novel mechanism by which endothelial miR-125a and let-7e-mediated regulation of interleukin-6 (IL-6) signaling can manipulate vasculogenic mimicry (VM) formation of MDA-MB-231 breast cancer cells. We found that endothelial IL-6 levels were significantly higher in response to cisplatin treatment, whereas levels of IL-6 upon cisplatin exposure remained unchanged in MDA-MB-231 breast cancer cells. We additionally found an inverse correlation between IL-6 and miR-125a/let-7e expression levels in cisplatin treated ECs. Interestingly, IL-6, IL-6 receptor (IL-6R), and signal transducer and activator of transcription 3 (STAT3) genes in the IL-6 pathway are closely regulated by miR-125a and let-7e, which directly target its 3' untranslated region. Functional analyses revealed that endothelial miR-125a and let-7e inhibit IL-6-induced adhesion of monocytes to ECs. Furthermore, conditioned medium from cisplatin treated ECs induced a significantly higher formation of VM in MDA-MB-231 breast cancer cells as compared to that from intact ECs; this effect of cisplatin treatment was abrogated by concurrent overexpression of miR-125a and let-7e. Overall, this study reveals a novel EC-tumor cell crosstalk mediated by the endothelial miR-125a/let-7e-IL-6 signaling axis, which might improve chemosensitivity and provide potential therapeutic targets for the treatment of cancer.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.4
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• pp.161-167
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• 2015

These commensal intestinal bacteria can enhance the immune system and aid in nutrient absorption but can also act as opportunistic pathogens. Among these intestinal bacteria, the anaerobic Bacteroides fragilis are divided into enterotoxigenic B. fragilis (ETBF) which secrete the B. fragilis toxin (BFT) and non-enterotoxigenic B. fragilis (NTBF) which do not secrete BFT. ETBF can cause diarrhea and colitis in both humans and livestock but can also be found in asymptomatic individuals. ETBF is predominantly found in patients with inflammatory diarrheal diseases and traveller's diarrhea. Several clinical studies have also reported an increased prevalence of ETBF in human patients with inflammatory bowel disease (IBD), colitis and colorectal cancer. In small animal models (C57BL/6 wild-type mice, germ-free mice, multiple intestinal neoplasia (Min) mice, rabbits and Mongolian gerbils), ETBF have been found to initiate and/or aggravate IBD, colitis and colorectal cancer. BFT induces E-cadherin cleavage in intestinal epithelial cells resulting in loss of epithelial cell integrity. Subsequent activation of the ${\beta}$-catenin pathway leads to increased cellular proliferation. In addition, ETBF causes acute and chronic colitis in wild-type mice as well as enhances tumorigenesis in Min mice via activation of the Stat3/Th17 pathway. Currently, ETBF can be detected using a BFT toxin bioassay and by PCR. Advances in molecular biological techniques such as real-time PCR have allowed both researchers as well as clinicians to rapidly detect ETBF in clinical samples. The emergence of more sensitive techniques will likely advance molecular insight into the role of ETBF in colitis and cancer.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.293-301
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• 2005

We conducted several different leaching experiments for assessing the potential environmental risk when utilizing recycled concrete for stabilizing bridge pier. The methods include continuous batch leaching test (DIN 38414-S4), availability test (NEN 7341), pH-stat test (CEN/TC 292/WG6) and tank diffusion test (NEN 7345). The concentration ranges vary depending on the testing method. Nearly all the trace elements were low, some elements recording under detection limit. The maximum concentrations for trace elements leached throughout the whole tests are (as mg/L); Cd (0.029), Cu (0.437), Pb (0.14), Ni, Zn (0.95), Hg (0.005). Although the testing methods we used in this study are much more rigorous than other commonly adapted method including TCLP and domestic testing method for solid waste, the trace elemental concentrations are under the criteria for hazardous material set by the TCLP and domestic method. The result seems to suggest that applying the recycled concrete on stream water will be accepatable practice as for as trace elements are concerned. However, the influence of inorganics such as Ca, Mg, Ni and $SO_4^{2-}$ on aquatic ecology should be further examined.

• Journal of Acupuncture Research
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• v.24 no.4
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• pp.167-181
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• 2007

Objectives: To evaluate expression of MIF mRNA, MIF, $TNF-{\alpha}$, $IL-6R-{\alpha}$, STAT-3, $NF-{\kappa}B$ p65, COX-2 and iNOS, MMP-9mRNA after injecting deer antler herbal acupuncture solution in a LPS rat model. Methods: The experiment was divided in category of the control group, RA group, and NA group. RA was induced in the mice via injecting 300ug/kg LPS. The deer antler herbal acupuncture solution 50ug/kg was applied on $ST_{35}$(犢鼻) and EX-LE201(內膝眼) for 19days from $3^{rd}$ day of RA inducement. Results: 1. In the deer antler herbal acupuncture solution treated RAW 264.7cell, the mRNA expression of cytokines, RA related inflammation factors, such as the MIF, COX- 2, iNOS, and MMP-g reduced concentration dependently. 2. In the deer antler herbal acupuncture treated mice's synovial membrane, decrease in the cell replication of synovial joint cells, regeneration of blood vessel, fibrosis and fibroblastic cells expansion were observed. 3. Positive reaction of RA-related cytokines MIF, $TNF-{\alpha}$, $IL-6R-{\alpha}$, STAT3, COX-2, iNOS, $NF-\;{\kappa}B$ p65, MMP-9 was reduced. Conclusion : On the basis of the results, it was concluded that deer antler herbal acupuncture extract has significant protecting ability against acute progressive RA by inhibiting the production of MIF, as a top in cytokines related to inflammation.

• Korean Journal of Food Science and Technology
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• v.54 no.1
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• pp.28-34
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• 2022

Glioblastoma is the most common primary malignant brain tumor and has an extremely poor prognosis. Glioblastoma stem cells (GSCs) contribute to tumor initiation, recurrence, and resistance to therapy, and are thus a key therapeutic target. The peel of Citrus unshiu Markovich has been used in traditional medicine in East Asia to treat various diseases. In this study, we investigated the anticancer activity and molecular mechanism of the chloroform extract of this natural product (CECU) in U87MG GSCs. The results show that CECU inhibited the proliferation, tumorsphere formation, and migration of U87MG GSCs by causing cell cycle arrest at the G0/G1 phase and apoptosis. In addition, CECU downregulated key cancer stemness regulators, including CD133, Oct4, Nanog, integrin α6, ALDH1A1, and STAT3 signaling in U87MG GSCs. Furthermore, CECU significantly suppressed in vivo tumor growth of U87MG GSCs in a chorioallantoic membrane model. Therefore, CECU can be utilized as a natural medicine for the prevention and treatment of glioblastoma.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.6-11
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• 1995

In order to screen microorganism producing lactic acid with high productivity from nature, we used a medium containing 100 g/l glucose and selected several microorganisms producing more than 80 g/l L-lactic acid. We investigated their physiological characteristics and compared them. The best microorganism was identified as Lactobacillus casei subsp. rhamnosus. The optimum pH for growth and production of lactic acid was 6.0 and this strain showed the highest growth rate at around 30$\circ$C , but the optimum temperature for lactic acid production was 45$\circ$C . The growth was inhibited proportionally from 50 g/l to 300 g/l of glucose and the maximal cell mass increased according to increasing the concentration of corn steep liquor (CSL) protein up to 30 g/l. In batch fermentation for lactic acid production, we produced 128 g/l L-lactic acid with 20 g/l CSL protein and 150 g/l glucose in 35 hours. In pH-stat fed-batch fermentation, we were able to produce 183 g/l L-lactic acid.