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이재란,백찬기,김수용,김석원 한국광학회 2014 Current Optics and Photonics Vol.18 No.5
A polarization fluorescence correlation spectroscopy system based on a confocal microscope was built to study the rotational and translational diffusion of CdSe/CdS quantum rods (Q-rods), with the same and different polarization states between the polarizer and the analyzer (i.e. the XXX and XYY states). The rotational diffusion amplitude showed the dependences on polarization of 0.75±0.05 in the XXX state and 0.26±0.03 in the XYY state, when the translational diffusion amplitude was 1. The diffusion coefficients of the Q-rods were found based on their translational and rotational diffusion times in the two polarization states, in solutions with viscosity ranging from 0.9 to 6.9 cP. The translational and rotational diffusion coefficients ranged from 1.5×10-11 to 2.6×10-12 m2 s-1 and from 2.9×105 to 5.6×104 s-1, respectively.
박형주,백찬기,Masataka Kinjo,강봉균 한국분자세포생물학회 2008 Molecules and cells Vol.26 No.1
We employed dual color Fluorescence Cross Correlation Spectroscopy (FCCS) to measure the interaction between PKA regulatory (RII) and catalytic subunits (CAT) in living cells. Elevation of intracellular cAMP with forskolin decreased the cross-correlation amplitude between RFP-fused RII (RII-mRFP) and GFP-fused CAT (CAT-EGFP) by 50%, indicating that cAMP elevation leads to dissociation of RII-CAT complexes. Moreover, diffusion coefficient analysis showed that the diffusion rate of CAT-EGFP was significantly increased, suggesting that the decreased RII-CAT association caused by cAMP generated free CAT subunits. Our study demonstrates that in vivo FCCS measurements and their quantitative analysis permit one not only to directly quantify protein-protein interactions but also to estimate changes in the intracellular cAMP concentration.
이승민,조정인,최수진,김동하,류재원,김인기,우동철,성영훈,정진용,백인정,백찬기,노진경,이상욱,하창훈 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00
Background Tumor-derived exosomes are critical elements of the cell–cell communication response to various stimuli. This study aims to reveal that the histone deacetylase 5 (HDAC5) and p53 interaction upon radiation in hepatocellular carcinoma intricately regulates the secretion and composition of exosomes. Methods We observed that HDAC5 and p53 expression were significantly increased by 2 Gy and 4 Gy radiation exposure in HCC. Normal- and radiation-derived exosomes released by HepG2 were purified to investigate the exosomal components. Results We found that in the radiation-derived exosome, exosomal Maspin was notably increased. Maspin is known as an anti-angiogenic gene. The expression of Maspin was regulated at the cellular level by HDAC5, and it was elaborately regulated and released in the exosome. Radiation-derived exosome treatment caused significant inhibition of angiogenesis in HUVECs and mouse aortic tissues. Meanwhile, we confirmed that miR-151a-3p was significantly reduced in the radiation-derived exosome through exosomal miRNA sequencing, and three HCC-specific exosomal miRNAs were also decreased. In particular, miR-151a-3p induced an anti-apoptotic response by inhibiting p53, and it was shown to induce EMT and promote tumor growth by regulating p53-related tumor progression genes. In the HCC xenograft model, radiation-induced exosome injection significantly reduced angiogenesis and tumor size. Conclusions Our present findings demonstrated HDAC5 is a vital gene of the p53-mediated release of exosomes resulting in tumor suppression through anti-cancer exosomal components in response to radiation. Finally, we highlight the important role of exosomal Maspin and mi-151a-3p as a biomarker in enhancing radiation treatment sensitivity.
13.56㎒로 여기되는 도파관 CO₂ 레이저의 동작특성 및 Xe 첨가효과
김영식(Yeong-Sik Kim),권혁상(Hyuk-Sang Kwon),신교철(Kyo-Chul Sin),백찬기(Chan-Gi Back),김윤명(Youn-Myung Kim),박재환(Jae-Whan Park) 한국광학회 1992 한국광학회지 Vol.3 No.4
금속(stainless steel)과 판유리를 이용한 도파관 탄산가스 레이저를 제작하고 출력특성을 조사하였다. 도파관의 길이는 50 ㎝, 내부 단면적은 6×6 ㎟이며 13.56 ㎒의 고주파로 횡여기시키는 방식이다. 가스 밀폐형으로 동작될 때 입력전력과 가스압력 변화에 의한 레이저 출력의 측정 결과 가스 분압비 He : Co₂ : N₂ : Xe=6 : 1 : 2: 1, 전체 가스압력 50 Torr, 고주파 입력전력이 180 W인 조건에서 최대출력 9.5W로 발진하고 있다. A sealed-off waveguide CO₂ laser with a length of 50 ㎝ and a cross-sectional area of 6 6 ㎟ has been designed and constructed. The laser is transversely excited by RF (13.56 ㎒) discharge. Output characteristics of the laser has been investigated performing variations of total gas pressure, input rf power, and mixing ratios of gases. The maximum output power of 9.5 W was obtained under the condition of total gas pressure of 50 Torr, input rf power of 180 W, and gas mixture of 6 : 1 : 2 : 1 of He : CO₂ : N₂ : Xe.