• KSBB Journal
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• v.23 no.2
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• pp.177-182
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• 2008

In this study, crude extracts of the halophyte Limonium tetragonum and their solvent fractions were evaluated on anticancer activity in AGS and HT-29 human cancer cells using MTT assay. Each of the crude extracts (MeOH and $CH_2Cl_2$) of Limonium tetragonum showed a significant inhibitory effect on the growth of human cancer cells. The combined crude extracts of MeOH and $CH_2Cl_2$ were partitioned between $CH_2Cl_2$ and water. The organic layer was further partitioned between 85% aq. MeOH and n-hexane, and then the aqueous layer was fractionated with n-BuOH and $H_2O$, successively. Growth inhibition effects of crude extracts and their solvent fractions from Limonium tetragonum increased in a dose-dependent manner. Among them, 85% aq. MeOH, n-hexane and n-BuOH fractions revealed very good inhibition effects on the growth of human cancer cells. These results suggest that we can isolate active compounds from Limonium tetragonum to show much more strong anticancer activity.

• KSBB Journal
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• v.20 no.5 s.94
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• pp.376-382
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• 2005

Avermectin (AVM) $B_{1a}$ produced by Streptomyces avermitilis via polyketide pathway is a secondary metabolite with powerful anthelmintic and insecticidal activities, thus being used as an efficient agent in the field of agriculture and animal health. It has been reported that a precursor for AVM $B_{1a}$ biosynthesis was isoleucine and the biosynthetic pathway of AVM $B_{1a}$ was closely similar to that of fatty acid. Based on understanding of the biosynthetic pathway of AVM $B_{1a}$, we intended to screen various mutants resistant against O-methyl threonine (OMT), an isoleucine-anti metabolite, and/or mutants resistant against p-fluoro phenoxy acetic acid (pFAC), an inhibitor of fatty acid biosynthesis. It was inferred that these mutants could produce AVM $B_{1a}$ more efficiently, due to the acquired capability of not only overproducing isoleucine intracellularly but also channelling metabolized carbon-sources into the polyketide pathway, thus leading to enhanced biosynthesis of AVM $B_{1a}$. The resulting mutant (PFA-1 strain) resistant against 100 ppm of pFAC was able to produce approximately 42 fold higher amount of AVM $B_{1a}$ compared to the parallel mother strain (4,200 vs. 100 units/l). In addition, through the process of continuous strain improvement program carried out by gradually increasing the OMT concentration, it was possible to obtain a more attractive mutant with greater AVM $B_{1a}$ production capacity (9,000 units/l). Notable was that significantly higher producer (12,000 units/l) could be selected through further screening of the resistant mutants, this time, to even higher concentration of PFAC. Meanwhile, through the analysis of AVM Bla production histograms (i.e., number of strains according to their AVM $B_{1a}$ biosynthetic ability) for the earlier strains in comparison with the high producers having the characteristics of resistance to OMT and pFAC, it was found that production stability of the high-yielding producers were remarkably improved, as demonstrated by the fact that larger proportion of the mutated strains had greater capability of AVM $B_{1a}$ biosynthesis ($71\%$ in the range between 5,000 and 7,000 units/L; $47\%$ in the range between 6,000 and 7,000 units/l). Based on these consequences, it was concluded that the rational screening strategy based on the understanding of the biosynthetic pathway of AVM $B_{1a}$ was very effective in obtaining high-yielding mutants with the features of enhanced production stability.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.119-126
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• 2012

State of problem: Cement-retained implant-supported prostheses are routinely used in dentistry. The use of high strength cements has become more popular with the increasing confidence in the stability of the implant-abutment screw connection and the high survival rates of osseointegrated implants. No clinical data on retention of metal copings using CAD/CAM. To evaluate retention of metal copings using CAD/CAM system bonded to short titanium abutment with four different cements and compare retentive strength of metal copings with sandblasting or without sandblasting before cementation. Forty titanium abutment blocks were fabricated and divided into 4 groups of 10 samples each. Forty metal copings with occlusal hole to allow for retention testing were fabricated using CAD/CAM technology. The four cements were Fujicem(Fuji, Japan), Maxcem Elite(Kerr, USA), Panavia F2.0(Kurarary, Japan) and Superbond C&B(Sunmedical, Japan). The copings were cemented on the titanium abutment according to manufacture's recommendation. All samples were stored for 24h at 37oC in 100% humidity and tested for retention using universal testing machine(Instron) at a crosshead speed of 1.0mm/min. Force at retentive failure was recorded in Newton. The mode of failure was also recorded. Means and standard deviations of loads at failure were analyzed using ANOVA and Paired t-test. Statistical significance was set at P<0.05. Panavia F2.0 provided significantly higher retentive strength than Fujicem, Maxcem Elite(P<0.05). Sandblasting significantly increased bond strength(P<0.05). The mode of failure was cement remaining principally on metal copings. Within the limitation of this study, Panavia F2.0 showed significantly stronger retentive strength than Fujicem, Maxcem Elite(p<0.05). The Ranking order of the cements to retain the copings was Panavia F2.0, Fujicem = Maxcem Elite. Sandblasting significantly increased bond strength(P<0.05). The retentive strength of metal copings on implant abutment were influenced by surface roughness and type of cements.

• KSBB Journal
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• v.24 no.2
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• pp.156-162
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• 2009

We examined saury, herring, gizzard shad kwamaegi to measure of microbic contamination rate of kwamegi that are sold in the market now. In the total bacteria, staphylococcus, peroxide value, and microorganisms is inhibited that from sample that we treated a substance with chitosan-ascorbate (CA) and other orders deep water (DW), ginseng steamed red and wine (GRW), NT (not treated). When we compared between SGRW and SNT, SCA show us more inhibition effect 0.22-0.49 log cycle in the total aerobacter. When we compared between HDW and HNT, HCA restraint 0.05-0.45log cycle, and when we compared between GDW and GNT, GCA inhibited 0.45 log cycle. In the coliform and E. coli, growths of microorganisms were inhibited followed order by treatment of CA, NT, and DW. GDW, HCA and HNT checked enough amount of water from the moisture measurement; but SGW, GCA, HEW and SCA showed 7-15% lack of moisture, and SNT and GNT have 10% more moisture. Peroxide value is changed to 41-51meq/kg when we did treat CA in there and a side that didn't add antimicrobial expressed the result numerically that 56-58meq/kg. In the sensory evaluation, customer gave preference to followed by Saury kwamaegi, herring, and gizzard shad kwamaegi. We have a point of view when kwamaeki manufactured if we add natural antibiotic and it uses to vacuum drying, we would inhibited of multiplication of microorganism, and of peroxides.