• 한국환경농학회지
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• 제34권3호
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• pp.244-251
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• 2015

BACKGROUND: Recent studies have described the importance of bacteria that can degrade polycyclic aromatic hydrocarbons (PAHs). Here we screened bacterial isolates from commercial gasoline for PAH degraders and characterized their ability to degrade PAHs, lipids and proteins as well as their enantioselective epoxide hydrolase activity, salt tolerance, and seawater survival. METHODS AND RESULTS: One hundred two bacteria isolates from commercial gasoline were screened for PAH degraders by adding selected PAHs on to the surface of agar plates by the sublimation method. A clear zone was found only around the colonies of PAH degraders, which accounted for 13 isolates. These were identified as belonging to Bacillus sp., Brevibacterium sp., Micrococcus sp., Corynebacterium sp., Arthrobacter sp., and Gordonia sp. based on 16S rRNA sequences. Six isolates belonging to Corynebacterium sp., 3 of Micrococcus sp., Arthrobacter sp. S49, and Gordonia sp. H37 were lipid degraders. Arthrobacter sp. S49 was the only isolate showing high proteolytic activity. Among the PAH-degrading bacteria, Arthrobacter sp. S49, Brevibacterium sp. S47, Corynebacterium sp. SK20, and Gordonia sp. H37 showed enantioselective epoxide hydrolase activity with biocatalytic resolution of racemic styrene oxide. Among these, highest enantioselective hydrolysis activity was seen in Gordonia sp. H37. An intrinsic resistance to kanamycin was observed in most of the isolates and Corynebacterium sp. SK20 showed resistance to additional antibiotics such as tetracycline, ampicillin, and penicillin. CONCLUSION: Of the 13 PAH-degraders isolated from commercial gasoline, Arthrobacter sp. S49 showed the highest lipid and protein degrading activity along with high active epoxide hydrolase activity, which was the highest in Gordonia sp. H37. Our results suggest that bacteria from commercial gasoline may have the potential to degrade PAHs, lipids, and proteins, and may possess enantioselective epoxide hydrolase activity, high salt tolerance, and growth potential in seawater.

• Archives of Pharmacal Research
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• 제25권5호
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• pp.608-612
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• 2002

The twelve-protostane analogues were synthesized from alisol B 23-acetate and assessed for their in vitro antitumor activity against six different human and murine tumor cell lines. Of the compounds synthesized, 23S-acetoxy-24R(25)-epoxy-11$\beta$,23S-dihydroxyprotost-13(17)-en-3-hy-droxyimine (12) exhibited significant cytotoxic activities against A549, SK-OV3, B16-F10, and HT1080 tumor cells with $ED_{50}/$ values of 10.0, 8.7 ,5.2, and 3.1 ${\mu}g$/ml, respectively. Furthermore, 23S-acetoxy-13(17),24R(25)-diepoxy-11$\beta$-hydroxyprotost-3-one (5), 13(17),24R(25)-diepoxy-11$\beta$, 23S-dihydroxyprotostan-3-one (6), 24R,25-epoxy-11$\beta$,23S-dihydroxyprotost-13(17)-en-3-one (7), and 11$\beta$,23S,24R,25-tetrahydroxyprotost-13(17)-en-3-one (9) showed moderate cytotoxic activities against 816-F10 and HT1080 tumor cells. These results mean that a hydroxyimino group at C-3 position in the protostane-type terpene enhances cytotoxic activity.

• 생명과학회지
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• 제24권3호
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• pp.242-251
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• 2014

국내에서 자생하는 P. thunbergiana 잎의 메탄올 추출물로부터 사람의 간암세포주, SK-HEP-1에 apoptosis를 유도하는 광과민성물질을 찾기 위해 연구를 시작하였다. Apoptosis를 유도하는 광과민성물질을 순수분리하기 위해 column chromatography법과 TLC법을 이용하였으며, 순수분리한 물질의 구조동정을 위하여 1D-NMR과 2D-NMR 및 FAB-MS분석을 실시하였다. P. thunbergiana 잎으로부터 크로마토그래피법을 이용해 순수분리한 M4-3 화합물의 흡광도를 측정한 결과 410 nm에서 최대 흡수를 보였고, 668, 502, 533, 607 nm에서 흡수 peak가 나타나는 녹색의 물질로 chlorophyll a, b와는 다른 물질이었다. FAB-MS 분석결과와 NMR 분석결과, 분자량 622의 132-hydroxy pheophorbide a methyl ester($C_{36}H_{28}N_2O_6$) 화합물로 porphyrin 환으로부터 Mg이온이 떨어져나간 pheophorbide a유도체화합물로 동정되었다. M4-3화합물을 SK-HEP-1세포에 대한 세포독성을 조사한 결과, 0.04 ${\mu}M$ 농도로 처리한 곳에서는 40% 세포증식 억제효과가 나타났고, 0.08 ${\mu}M$ 농도로 처리한 곳에서는 80% 세포증식 억제효과가 나타나 농도의존적이었다. 그리고 M4-3화합물을 동일한 농도로 처리하고, 광의 조사 유무에 따른 활성차이를 조사한 결과, 광을 조사한 곳에서만 세포독성이 나타났기 때문에 M4-3화합물은 광과민성물질이라는 것을 알 수 있었다. M4-3화합물을 처리하고 세포의 형태학적 변화를 관찰한 결과, 핵이 응축되었고, 소낭이 형성되었으며, DNA 단편화가 일어나는 등 apoptosis의 대표적인 현상들이 일어났기 때문에 M4-3화합물의 세포사멸은 광역학활성에 의한 apoptosis유도로 확인하였다.

• Biomolecules & Therapeutics
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• 제13권2호
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• pp.78-83
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• 2005

2,3,7,8-Tetrachlorodibenzo-p-dioxin(TCDD) has previously shown to induce neurotoxicity through intracellular $Ca^{2+}$ increase in rat neurons. In this study we investigated the role and signaling pathway of intracellular $Ca^{2+}$ in TCDD-induced inhibition of neuronal cell proliferation in SK-N-SH human neuronal cells. We found that TCDD(10nM) rapidly increased the level of intracellular $Ca^{2+}$, which was completely blocked by the extracellular $Ca^{2+}$ chelation with EGTA (1 mM) or by pretreatment of the cells with the non-selective cation channel blocker. flufenamic acid (200 ${\mu}M$). However, pretreatment of the cells with dantrolene (25 ${\mu}M$) and TMB-8(10 ${\mu}M$), intracellular $Ca^{2+}$-release blockers, or a voltage-sensitive $Ca^{2+}$ channel blocker, varapamil (100 ${\mu}M$), failed to block the TCDD-induced $Ca^{2+}$ increase in the cells. In addition, TCDD induced a rapid and transient activation of phatidvlinositol 3-kinase (PI3K) and extracellular signal-regulated kinase 1/2(ERK1/2), which was ingnificantly blocked by the pretreatment with BAPTA, an intracellular $Ca^{2+}$ chelator, and LY294002, a PI3K inhibitor. Furthermore, inhibitors of PI3K, ERK, or an intracellular $Ca^{2+}$ chelator further potentiated the anti-proliferative effect of TCDD in the cells. Collectively, the results suggest that intracellular $Ca^{2+}$ and PI3K-dependent activation of ERK 1/2 may be involved in the TCDD-induced inhibition of cell proliferation in SK-N-SH human neuronal cells.

• Journal of information and communication convergence engineering
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• 제13권3호
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• pp.189-196
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• 2015

In this paper, we present a rotating auto-zeroing offset cancellation technique, which can improve the performance of touch screen sensing circuits. Our target touch screen detection method employs multiple continuous sine waves to achieve a high speed for large touch screens. While conventional auto-zeroing schemes cannot handle such continuous signals properly, the proposed scheme does not suffer from switching noise and provides effective offset cancellation for continuous signals. Experimental results show that the proposed technique improves the signal-to-noise ratio by 14 dB compared to a conventional offset cancellation scheme. For the realistic simulation results, we used Cadence SPECTRE with an accurate TSP model and noise source. We also applied an asymmetric device size (10% MOS size mismatch) to the OP Amp design in order to measure the effectiveness of offset cancellation. We implemented the proposed circuit as part of a touch screen controller system-on-chip by using a Magnachip/SK Hynix 0.18-µm complementary metal-oxide semiconductor (CMOS) process.

• 항공우주시스템공학회지
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• 제13권5호
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• pp.9-15
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• 2019

In this paper, dynamic analysis of a nonlinear active vibration absorber is conducted with a time delay acceleration feedback to suppress the vibration of a nonlinear single degree of freedom primary system. The primary system consisting of linear and nonlinear cubic springs, mass, and damper is subjected to the multi-harmonic hard excitation with a parametric excitation. It is proposed to reduce the vibration of the primary system and the absorber by using a lead zirconate titanate (PZT) stack actuator in series with a spring in the absorber which configures as an active vibration absorber. The method of multiple scales (MMS) is used to obtain the approximate solution of the system under the internal resonance, subharmonic, superharmonic, and principal parametric resonance conditions simultaneously. Frequency and time responses of the system are investigated considering a delay in the feedback for the various parameters of the absorber configuration and controlling force.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권2호
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• pp.98-107
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• 2013

This work describes a 13b 100 MS/s 0.13 um CMOS four-stage pipeline ADC for 3G communication systems. The proposed SHA-free ADC employs a range-scaling technique based on switched-capacitor circuits to properly handle a wide input range of $2V_{P-P}$ using a single on-chip reference of $1V_{P-P}$. The proposed range scaling makes the reference buffers keep a sufficient voltage headroom and doubles the offset tolerance of a latched comparator in the flash ADC1 with a doubled input range. A two-step reference selection technique in the back-end 5b flash ADC reduces both power dissipation and chip area by 50%. The prototype ADC in a 0.13 um CMOS demonstrates the measured differential and integral nonlinearities within 0.57 LSB and 0.99 LSB, respectively. The ADC shows a maximum signal-to-noise-and-distortion ratio of 64.6 dB and a maximum spurious-free dynamic range of 74.0 dB at 100 MS/s, respectively. The ADC with an active die area of 1.2 $mm^2$ consumes 145.6 mW including high-speed reference buffers and 91 mW excluding buffers at 100 MS/s and a 1.3 V supply voltage.

• 생명과학회지
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• 제16권2호
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• pp.282-288
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• 2006

새송이버섯으로부터 활성추적법으로 항암활성이 있는 물질인 에르고스테롤 프록사이드를 분리하였다. 이 스테롤의 구조는 분광법과 NMR법으로 확인하였으며 분자식은 $C_{28}H_{44}O_3$이었다. 폐암과 난소암에 $IC_{50}$값은 각각 $7{\mu}M$과 $14{\mu}M$이었다. DNA단편화 실험에서 이 화합물은 암세포의 chromosimal DNA 를 사닥다리모양으로 분해하였고, 세포 분열주기의 억제실험에서 G1단계를 억제함을 관찰하였다.

• Biomolecules & Therapeutics
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• 제13권4호
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• pp.256-262
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• 2005

We examined the signaling molecules involved in the 6-hydroxydopamine (6-OHDA)-induced neuronal cell death and increase in cellular glutathione (GSH) level in SK-N-SH cells. The 6-OH-DA-induced cell death was significantly prevented by the pretreatment with N-acetylcysteine (NAC), a thiol antioxidant, and BAPTA, an intracellular $Ca^{2+}$ chelator. Although 6-OHDA induced ERK phosphorylation, the pretreatment with PD98059, an ERK inhibitor, did not block 6-OHDA-induced cell death. In addition, the 6-OHDA-induced activation of caspase-3, a key signal for apoptosis, was blocked by the pretreatment with NAC and BAPTA. While the level of reactive oxygen species (ROS) was significantly increased in the 6-OHDA-treated cells, the cellular GSH level was not altered for the first 6-hr exposure to 6-OHDA, but after then, the level was significantly increased, which was also blocked by the pretreatment with NAC and BAPTA, but not by PD98059. Depletion of GSH by pretreating the cells with DL-buthionine-(S,R)-sulfoximine (BSO), a glutathione synthesis inhibitor, rather significantly potentiated the 6-OHDA-induced death. In contrast to the pretreatment with NAC, 6-OHDA-induced cell death was not prevented by the post-treatment with NAC 30 min after 6-OHDA treatment. The results indicate that the GSH level which is increased adaptively by the 6-OHDA-induced ROS and intracellular $Ca^{2+}$ is not enough to overcome the death signal mediated through ROS-$Ca^{2+}$ -caspase pathway.

• Journal of Microbiology and Biotechnology
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• 제15권4호
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• pp.734-739
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• 2005

Myxobacterium sp. HK1, isolated from Korean soil, degrades cellulose, differentiates to fruiting body, and its 16s rDNA has $95\%$ similarity to Polyangium sp. An anticancer molecule, CDMHK, was identified from culture broth of Myxobacterium sp. HK1, and purified by Diaion HP20, Silica gel, Sephadex LH-20 chromatography, and preparative HPLC using an YMC OSD-A C18 column. The molecular structure and formula were determined to be $C_{l2}H_{l9}N_3O_2$ (M.W 237) by MS spectrometry, 300 MHz $^{1}H\;and\;^{13}C$ NMR. The CDMHK was not active against Escherichia coli, Staphylococcus aureus, and Candida albicans. However, this molecule inhibited the growth of various cancer cell lines. The $ED_{50}$ values of CDMHK were determined to be 0.147, 0.086, 0.18, 0.166, and 0.142 $\mu$g/ml against A549, SK-OV-3, SK-MEL-2, VF498, and HCTl5 cancer cell lines, respectively. In addition, the CDMHK was able to induce apoptosis of the CCRF-CEM cancer cell line, evidenced by DNA fragmentation assay and DAPI staining.