• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.248-259
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• 2007

The aim of this research was to study the effect of intermittent polymerization on marginal adaptation by comparing the marginal adaptation of intermittently polymerized composite to that of continuously polymerized composite. The materials used for this study were Pyramid (Bisco Inc., Schaumburg, U.S.A.) and Heliomolar (Ivoclar Vivadent, Liechtenstein) . The experiment was carried out in class II MOD cavities prepared in 48 extracted human maxillary premolars. The samples were divided into 4 groups by light curing method: group 1- continuous curing (60s light on with no light off), group 2-intermittent curing (cycles of 3s with 2s light on & 1s light off for 90s); group 3- intermittent curing (cycles of 2s with 1s light on & 1s light off for 120s); group 4- intermittent curing (cycles of 3s with 1s light on & 2s light off for 180s). Consequently the total amount of light energy radiated was same in all the groups. Each specimen went through thermo-mechanical loading (TML) which consisted of mechanical loading (720,000 cycles, 5.0 kg) with a speed of 120 rpm for 100hours and thermocycling (6000 thermocycles of alternating water of $50^{\circ}C$ and $55^{\circ}C$). The continuous margin (CM) (%) of the total margin and regional margins, occlusal enamel (OE), vertical enamel (VE), and cervical enamel (CE) was measured before and after TML under a $\times200$ digital light microscope. Three-way ANOVA and Duncan's Multiple Range Test was performed at 95% level of confidence to test the effect of 3 variables on CM (%) of the total margin: light curing conditions, composite materials and effect of TML. In each group, One-way ANOVA and Duncan's Multiple Range Test was additionally performed to compare CM (%) of regions (OE, VE CE). The results indicated that all the three variables were statistically significant (p < 0.05). Before TML, in groups using Pyramid, groups 3 and 4 showed higher CM (%) than groups 1 and 2, and in groups using Heliomolar. groups 3 and 4 showed higher CM (%) than group 1 (p < 0.05). After TML, in both Pyramid and Heliomo)ar groups, group 3 showed higher CM (%) than group 1 (p < 0.05) CM (%) of the regions are significantly different in each group (p < 0.05). Before TML, no statistical difference was found between groups within the VE and CE region. In the OE region, group 4 of Pyramid showed higher CM (%) than group 2, and groups 2 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). After TML, no statistical difference was found among groups within the VE and CE region. In the OE region, group 3 of Pyramid showed higher CM (%) than groups 1 and 2, and groups 2,3 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). It was concluded that intermittent polymerization may be effective in reducing marginal gap formation.

• Archives of Pharmacal Research
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• v.15 no.1
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• pp.30-34
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• 1992

In order to obtain acetaminophen, a popular analgesic-antipyretic, through microbial p-hydroxylation and N-acetylation of aniline, various fungi and bacteria were secreened. Among them, Streptomyces species were chosen for strain improvement by the use of interspecific protoplast fusion technique. Two interspecific fused strains were developed between S. rimosus (N-cetylation function) and S. aureofaciens (p-hydroxylation function) and also between S. lividans and S. globisporus. For efficient protoplast fusion and cell wall regeneration, various conditions were examined. In a typical experiment of mixed S rimosus ($pro^- \;his^-$) and S. aureofaciens ($ilv^-$) protoplasts with 40% (w/v) polythylene glycol 3350 (PEG) for 3 min gave $8.3\times10^{-7}$ of fusion frequency. Treatment of mixed S. lividans (pant-) and S. globisporus (leu-) protoplasts with 50% (w/v) PEG for 3 min at $30^\circ{C}$ gave $1.2\times10^{-6}$ of frequency. Among the fused strains, up to 40-50% increase in p-hydroxylation power was observed. To investigate the possibility of plasmid involvement in p-hydroxylation power was observed. To investigate the possibility of plasmid involvement in p-hydroxylation of acetanilide, plasmid curing was attempted. We found that cells treated with acriflavine (at the frequency of 100%) and cells regenerated from protoplsts of S. auroefaciens (2% frequency) lost their p-hydroxylation function.

• Economic and Environmental Geology
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• v.18 no.2
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• pp.151-157
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• 1985

Events detected by the KIER microearthquake network operated in the Southern Part of Korea for 265 days in 1982~1984 were reviewed, and some of them were identified to be a dynamite explosion from several construction sites. The purpose of the present work is to determine the crustal structure of the Southern Korea using the time-destance data obtained from such explosion seismic records. The time·distance data can be well explained by a crustal model composed of four horizontal layers of which thickness, p and s-wave velocity ($V_p$ and $V_s$) are characterized as follows. 1st layer (surface) ; 0~2km, $V_p=5.5km/sec$, $V_s=3.3km/sec$ 2nd layer (upper crust) ; 2~15km, $V_p=6.0km/sec$, $V_s=3.5km/sec$ 3rd layer (lower crust) ; 15~29km, $V_p=6.6km/sec$, $V_s=3.7km/sec$ 4th layer (upper mantle) ; 29km~ , $V_p=7.7km/sec$, $V_s=4.3km/sec$ The relatively shallow crust·mantle boundary and low $P_n$ velocity compared with the mean values for stable intraplate region are noteworthy. Supposedely, it is responsible for the high heat flow in the South-eastern Korea or an anomalous subterranean mantle. The mean $V_p/V_s$ ratio calculated from the relation between p-wave arrival and s-p arrival times appears to be 1.735 which is nearly equivalent to the elastic medium of ${\lambda}={\mu}$. However, the ratio tends to be slightly larger with the depth. The ratio is rather high compared with that of the adjacent Japanese Island, and the fact suggests that the underlying crust and upper mantle in this region are more ductile and hence the earthquake occurrences are apt to be interrupted. As an alternative curstal model, a seismic velocity structure in which velocities are successively increased with the depth is also proposed by the inversion of the time·distance data. With the velocity profile, it is possible to calculate a travel time table which is appropriate to determine the earthquake parameters for the local events.

• Advances in pediatric surgery
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• v.15 no.1
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• pp.27-37
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• 2009

Neuroblastoma is the most common extracranial solid tumor in children. We retrospectively analyzed the results of neuroblastoma treatment of 191 patients (116 males and 75 females) treated between January 1986 and December 2005 at the Department of Pediatric Surgery and the Department of Pediatrics, Seoul National University Children's Hospital. The mean age at diagnosis was 3.1 years (0.1 yrs - 13.5 yrs). Forty-seven patients were under 1 year of age. The mean follow-up period was 57.3 months (24 days - 19.1 yrs). Patients were classified into two groups according to the completeness of resection of the primary tumor; (1) gross total resection (GTR) and (2) incomplete resection (IR). The number of patients in stages I, II, III, IV, IV-S were 17 (8.9 %), 12 (6.3 %), 43 (22.5 %), 114 (59.7 %), 4 (2.1 %), respectively. GTR was achieved in 120 patients and IR in 71 (22 stage III, 47 stage IV, 1 stage IV-S, 1 brain). Overall survival (OS) was 65.2 % and event-free survival (EFS) was 48.6 %. EFS were 100 %, 75 %, 66.8 %, 31.3 %, 75 % at stage I, II, III, IV, IV-S, respectively. There was no significant difference in EFS according to the completeness of resection. EFS was improved in GTR group (p=ns) of stage III, but by contrast, stage IV patients showed worse EFS in GTR group. EFS was improved significantly after the introduction of autologous stem cell transplantation (ASCT) (58.1% vs. 40.6%, p=.029). The EFS improved significantly after the introduction of ASCT in IR group (p=.009) rather than GTR group (p=ns). The EFS of the patients under 1 year of age (N=47) was better than the patients over 1 year of age (N=144) significantly (75.5 % vs. 39.4 %, p=.0034). The prognosis of neuroblastoma was related to the INSS stage and age at diagnosis. The survival of IR group significantly improved after ASCT.

• KSBB Journal
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• v.20 no.1 s.90
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• pp.46-49
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• 2005

Curdlan, a natural $\beta-1,3-glucan,$ has been studied as drug carrier due to its unique properties including its thermal gelling characters. In this study, curdlan was chemically acetylated for pH-sensitive drug delivery. Curdlan acetate microspheres(CAMs) were prepared by the solvent evaporation method. The size of the CAMs was below $200{\mu}m.$ The drug loading efficiency of microspheres was approximately $58.44\%$. In the swelling test, the CAMs showed pH-sensitive behavior. The swelling capacity of microspheres at pH 7.4 was much greater than at pH 1.4. Also, release rate of indomethacin(IND) at pH 7.4 from the CAMs was faster than that at pH 1.4. Therefore the CAMs have potential for the controlled release of IND over an extended period of time.

• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.465-472
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• 2019

Candida albicans is an opportunistic human pathogen that causes infections. Candidiasis is often related to antifungal resistance because the pathogen has the ability to form biofilms. In a previous study, we found that the Salvia miltiorriza ethanol extract demonstrated anticandidal activity by altering membrane permeability and inhibiting the cell wall synthesis in C. albicans. Our results here demonstrate that $78{\mu}g/ml$ of the S. miltiorriza extract significantly diminished the early stage biofilms formed by 10 clinical C. albicans isolates by 51.3%; this was analyzed by 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide salt (XTT) reduction assay. The effect of the S. miltiorrhiza extract on the adhesion of C. albicans cells to polystyrene plates and germ tube formation was examined via microscopic investigation. Although the density of the adhered cells was remarkably reduced up on incubation with $39{\mu}g/ml$ S. miltiorrhiza extract, germ tube formation by C. albicans was rarely affected. Quantitative real-time PCR analysis showed that the S. miltiorrhiza extract downregulated the expression of C. albicans hypha-specific genes, EAP1 by 34.7% (p < 0.001), ALS1 by 45.0% (p < 0.001), ALS3 by 48.1% (p < 0.001), and ECE1 by 21.3% (p = 0.006), respectively. Our data suggest that the S. miltiorrhiza ethanol extract significantly inhibited the early stage of biofilm formation by C. albicans by interfering with cell adhesion, by downregulating EAP1, ALS1 and ALS3, and presumably by modifying the cell wall and membrane structure.

• Applied Biological Chemistry
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• v.31 no.1
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• pp.92-99
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• 1988

The responses of brain acetylcholinesterase and plasma cholinesterase activities were examined in chicken given oral doses of an organophosphorus insecticides. Acute oral $LD_{50}$ of terbufos was 1.82mg/kg, and terbufos sulfone was 2.85mg/kg, terbufos sulfoxide, terbufoso xon, terbufosoxon sulfone and terbufosoxon sulfoxide were about $0.30{\sim}0.79mg/kg$, respectively. Acute oral $LD_{50}$ of phorate was 1.02mg/kg, and phorate sulfone was 1.73mg/kg, phorate sulfoxide, phoratoxon, phoratoxon sulfoxide and phoratoxon sulfone were about $0.36{\sim}0.63mg/kg$, respectively. Dosages of 50% inhibition for brain AChE and plasma ChE activities in chicken at 60 mins after oral administration of organop hosphorus insecticides were $35.3{\pm}6.8%\;and\;17.4{\pm}3.6%$ of acute oral $LD_{50}$, respectively. Activities of brain AChE and plasma ChE in chicken at 60 mins after oral administratration of acute oral $LD_{50}$ of organophosphorus insecticides were inhibited by $83.7{\pm}3.9%\;and\;93.3{\pm}2.2%$, respectively.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.88-95
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• 1999

구강내의 교정 장치는 미생물 전파에 있어서 다양한 장소를 제공한다. 치태는 치아 우식증 발생에 있어 매우 큰 역할을 하며 미생물, 비세포성 물질로 구성되어 있다. 본 연구의 목적은 생체외에서 교정용에서의 인공 치태 생성에 영향을 주는 요인을 평가하는 것이다. Streptococcus mutans type c는 $CO_2$ incubator내의 $37^{\circ}C$에서 brain heart infusion broth에서 배양 되었다. 중절치에 사용하는 9개의 $.018"{\times}.025"$ standard edgewise brackets을 3개씩 비이커의 배양액에 매달았다. 3개 비이커의 배양액 pH는 각 각 pH 5.5, 7.0 그리고 8.5로 조절되었다. 5시간 후에 비이커에서 각각의 bracket을 꺼내서, bracket의 평균 무게를 측정하였다. 배지의 stirring effect를 측정하기 위하여 3개씩 $.018"{\times}.025"$ standard edgewise brackets을 2개의 비이커에 위치시켰다. 12개의 brackets을 $CaCl_2$(0.25, 1.0, 4.0 그리고 16.0mM). KCl(2.5, 10, 40 그리고 160mM) 그리고 $MgCl_2$(0.1, 0.4, 1.6, 그리고 6.4mM) 용액에 각각 매달았다. 6개의 $.018"{\times}.025"$ standard edgewise brackets, 6개의 $.022"{\times}.028"$ Roth brackets과 6개의 $.022"{\times}.028"$ Broussard brackets을 각각의 비이커 내에 매달았다. 배양액 내에서 5시간 동안 배양한 후 각각의 brackets을 근사값의 milligram 단위로 측정하였다. 그룹 사이의 차이는 Mann-Whitney와 Kruskal-Wallis tests를 이용하여 비교하였다. p value<0.05의 조건에서 이들의 차이는 통계학적 유의성을 갖는다. 5시간 동안 pH 5.5에서 배양된 Streptococcus mutans에 의해 형성된 인공 치태는 pH 7.0 이나 pH 8.5에서 배양된 것보다 작았다(p<0.05). 인공 치태는 배양하는 동안 저어졌을 때 더 많이 형성되었다(p<0.05). 결론적으로 bracket에 형성된 인공 치태는 좀 더 높은 알칼리성 배지에서 배양됨으로써, 그리고 배양 동안 배지를 저어줌으로써 유의성있게 증가하였다. 그러나 배지의 $CaCl_2,\;KCl,\;MgCl_2$의 농도와 상업적으로 다른 종류의 이용 가능한 교정용 bracket에 대해서는 유의한 차이가 없었다.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.157-164
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• 2014

Objective of this research was to develop root media containing expanded rice hull (ERH) and carbonized rice hull (CRH). To achieve this, the physico chemical properties of two materials were analysed and blended with peatmoss (PM) or coir dust (CD) with various ratio. Based on the physical properties of the blended materials, 4 root media were selected for future experiment. After the analysis of pH and EC of the selected root media, the kinds and amount of pre-planting nutrient charge fertilizers (PNCF) incorporated into each root medium were varied, and then, final chemical properties of the root media were analysed. The total porosity (TP), container capacity (CC), and air-filled porosity (AFP) were 81.3%. 39.9%, and 41.4% in ERH and 77.6%, 64.1%, and 13.5% in CRH, respectively. The percentage of easily available water (EAW, from CC to 4.90 kPa tension) and buffering water (BW, 4.91-9.81 kPa tension) were 11.37% and 5.27%, in ERH and 17.26% and 14.28% in CRH, respectively. The pH of ERH was 7.1, but it was extremely high in CRH such as 11.2. The EC and CEC were $1.31dS{\cdot}m^{-1}$ and $12.1meq{\cdot}100g^{-1}$ in ERH and $6.53dS{\cdot}m^{-1}$ and CEC 7.79 $meq{\cdot}100g^{-1}$ in CRH, respectively. The ranges of TP, CC and AFP in 4 selected media (PM + ERH, 6:4, v/v; CD + ERH, 8:2; PM + CRH, 7:3; CD+CRH 6:4) were 89.2-90.3%, 67.3-81.8%, and 8.3-21.9%, respectively. The pHs and ECs in root media containing peatmoss such as PM + ERH (6:4) and PM + CRH (7:3) were 4.0-4.3 and $0.33-0.365dS{\cdot}m^{-1}$, whereas those of CD + CRH were 7.4-7.9 and $1.282dS{\cdot}m^{-1}$. The pHs and ECs, however, analysed before and after the incorporation of PNCF in each root medium were not significant different. This result indicated that the incorporated fertilizers in PNCF to adjust medium pH did not dissolve enough to influence medium pH, but it is very normal in root media containing dolomitic lime and sulfur powder in adjusting pH. The Information obtained in this study may facilitate an effective formulation of root media containing rice hulls.

• BMB Reports
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• v.32 no.2
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• pp.127-132
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• 1999

The NAD(P)H-quinone oxidoreductase (EC 1. 6. 99. 2) was purified from S. cerevisiae. The native molecular weight of the enzyme is approximately 111 kDa and is composed of five identical subunits with molecular weights of 22 kDa each. The optimum pH of the enzyme is pH 6.0 with 1,4-benzoquinone as a substrate. The apparent $k_m$ for 1,4-benzoquinone and 1,4- naphthoquinone are 1.3 mM and $14.3\;{\mu}M$, respectively. Its activity is greatly inhibited by $Cu^{2+}$ and $Hg^{2+}$ ions, nitrofurantoin, dicumarol, and Cibacron blue 3GA. The purified NAD(P)H-quinone oxidoreductase was found capable of reducing aromatic nitroso compounds as well as a variety of quinones, and can utilize either NADH or NADPH as a source of reducing equivalents. The nitroso reductase activity of the purified NAD(P)H-quinone oxidoreductase is strongly inhibited by dicumarol.