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Choi, Joonsung,Oh, Soon Nam,Yeo, Dong-Myung,Kang, Won Kyung,Jung, Chan-Kwon,Kim, Sang Woo,Park, Michael Yong WJG Press 2015 World journal of gastroenterology Vol.21 No.2
<P>To assess the role of computed tomography (CT) and magnetic resonance imaging (MRI) and establish imaging criteria of lymph node metastasis in early colorectal cancer.</P>
걷기 운동 시 심박수와 가속도센서를 이용한 VO<sub>2max</sub> 간접측정법 개발
박준성 ( Joonsung Park ),이병선 ( Byungsun Lee ),최현민 ( Hyunmin Choi ),박준성 ( Joonsung Park ),홍규석 ( Gyuseog Hong ),노호성 ( Hosung Nho ),( Joonsung Park ) 한국스포츠정책과학원(구 한국스포츠개발원) 2017 체육과학연구 Vol.28 No.1
[목적] 본 연구는 20대 남녀를 대상으로 일정속도로 걷기 시 심박수와 가속도센서를 이용하여 신뢰도와 타당도, 경제성이 높은 VO<sub>2max</sub> 간접측정법을 개발하였다. [방법] 총 107명(남성: 55명, 여성: 52명)의 연구 대상자는 신체구성 측정 후 운동부하테스트와 두 번의 1,600 m 걷기(빠르게 걷기, 일정속도 걷기)에 참여하였다. 연구대상자의 연령과 신체적 특성, 그리고 걷기 시 측정된 시간, heart rate (HR), 또는 HR과 activity count per minute (ACM)의 비율(HR/ACM)을 변인으로 회귀분석을 시행하였다. 개발된 추정식의 타당도 검증을 위하여 직접법에 의한 VO<sub>2max</sub>와 추정식에 의한 VO<sub>2max</sub>의 상관관계분석과 예측잔차합제곱(predicted residual sum of squares)를 시행하였다. 또한, 직접법에 의한 VO<sub>2max</sub>와 추정식에 의한 VO<sub>2max</sub>의 차이를 분석하기 위하여 Bland-Altman plotting과 선형회귀분석을 실시하였다. [결과] 구간별(400 m, 800 m, 1,200 m, 1,600 m) HR/ACM과 걷기시간이 성별, 연령과 함께 직접법에 의한 VO<sub>2max</sub>와 유의한 상관관계가 나타났다. 모든 구간에서 추정식이 개발되었으나 400m에서만 직접법에 의한 VO<sub>2max</sub>와 차이가 없었다(R2: 0.675, %SEE: 10.7). VO<sub>2max</sub>=121.659+6.656×Gender-0.865×Age-9.540×Time-2460.952×HR/ACM(Gender, 0=female, 1=male: Time, hundredth of a minute: HR, heart rate: ACM, activity count per minute). 모든 구간에서 빠르게 걷기보다 일정속도로 걷기 시 운동강도(%HRmax)가 낮게 나타났다. [결론] 따라서 본 연구를 통해 개발된 추정식을 통해 보다 짧은 거리 또는 보다 낮은 강도의 걷기를 통해 20대 성인의 VO<sub>2max</sub>측정이 가능할 것으로 사료된다. [Purpose] The purpose of this study was to develop the new indirect method assessing maximal oxygen uptake (VO<sub>2max</sub>) using heart rate (HR) and accelerometer during walk exercise. [Methods] One hundred seven participants (55 male, 52 female) performed a graded exercise test to determine VO<sub>2max</sub> and two types of 1,600 m walk exercises (fast walk and pace controlled walk). The equations for estimating VO<sub>2max</sub> was developed by stepwise multiple regression. The validity of developed equations tested through the correlation between measured VO<sub>2max</sub> and estimated VO<sub>2max</sub>, was assessed by predicted residual sum of squares, and Bland-Altman plotting. [Results] VO<sub>2max</sub> was correlated with time, and HR/activity count per minute (ACM) measured in pace controlled walk exercise at all distance (400 m, 800 m, 1,200 m, 1,600 m). The equations were valid significantly and their multiple correlation coefficients or standard estimated error were similar to that Åstrand-Rhyming cycle ergometer test or Rockport 1 mile walk test. Using HR/ACM in pace controlled walk (400 m), it was possible to estimate VO<sub>2max</sub> (R<sup>2</sup>: 0.675, %SEE: 10.7). The equation was: VO<sub>2max</sub>=121.659+6.656×Gender-0.865×Age-9.540×Time-2460.952×HR/ACM (Gender, 0=female, 1=male: Time, hundredth of a minute: HR, heart rate: ACM, activity count per minute). [Conclusion] Estimation equations developed in this study are considered to estimate VO<sub>2max</sub> through a shorter distance, or a lower intensity of walk exercise. It is required studies to target a wide range of ages or to develop walk test on a lower bpm.
Non-Invasive in vivo Loss Tangent Imaging: Thermal Sensitivity Estimation at the Larmor Frequency
Choi, Narae,Kim, Min-Oh,Shin, Jaewook,Lee, Joonsung,Kim, Dong-Hyun Korean Society of Magnetic Resonance in Medicine 2016 Investigative Magnetic Resonance Imaging Vol.20 No.1
Visualization of the tissue loss tangent property can provide distinct contrast and offer new information related to tissue electrical properties. A method for non-invasive imaging of the electrical loss tangent of tissue using magnetic resonance imaging (MRI) was demonstrated, and the effect of loss tangent was observed through simulations assuming a hyperthermia procedure. For measurement of tissue loss tangent, radiofrequency field maps ($B_1{^+}$ complex map) were acquired using a double-angle actual flip angle imaging MRI sequence. The conductivity and permittivity were estimated from the complex valued $B_1{^+}$ map using Helmholtz equations. Phantom and ex-vivo experiments were then performed. Electromagnetic simulations of hyperthermia were carried out for observation of temperature elevation with respect to loss tangent. Non-invasive imaging of tissue loss tangent via complex valued $B_1{^+}$ mapping using MRI was successfully conducted. Simulation results indicated that loss tangent is a dominant factor in temperature elevation in the high frequency range during hyperthermia. Knowledge of the tissue loss tangent value can be a useful marker for thermotherapy applications.
Lee, Joonsung,Choi, Narae,Seo, Jin Keun,Kim, Dong-Hyun Published for the American Association of Physicis 2017 Medical physics Vol.44 No.9
<P>Conclusions: The proposed reconstruction method not only determines electrical properties, but also circularly polarized component and longitudinal component of electric fields using an iterative process. The proposed method can quantitatively detect the conductivity of the small anomalies better than conventional methods. (C) 2017 American Association of Physicists in Medicine</P>
Park, Hoon Suk,Choi, Joonsung,Kim, Hyung Wook,Baik, Jun Hyun,Park, Cheol Whee,Kim, Young Ok,Yang, Chul Woo,Jin, Dong Chan SAGE Publications 2018 The journal of vascular access Vol.19 No.3
<P>Conclusion: An exchange with the over-the-guidewire method from a non-tunneled to a tunneled catheter was comparable to a de novo catheter placement technique. Therefore, this method should be viewed more favorably and should especially be considered for acute kidney injury patients.</P>
Liu, Haidan,Hwang, Joonsung,Li, Wei,Choi, Tae Woong,Liu, Kangdong,Huang, Zunnan,Jang, Jae-Hyuk,Thimmegowda, N.R.,Lee, Ki Won,Ryoo, In-Ja,Ahn, Jong-Seog,Bode, Ann M.,Zhou, Xinmin,Yang, Yifeng,Erikson, American Association for Cancer Research 2014 CANCER PREVENTION RESEARCH Vol.7 No.1
<P>Mitogen- and stress-activated kinase 1 (MSK1) is a nuclear serine/threonine protein kinase that acts downstream of both extracellular signal-regulated kinases and p38 mitogen-activated protein kinase in response to stress or mitogenic extracellular stimuli. Increasing evidence has shown that MSK1 is closely associated with malignant transformation and cancer development. MSK1 should be an effective target for cancer chemoprevention and chemotherapy. However, very few MSK1 inhibitors, especially natural compounds, have been reported. We used virtual screening of a natural products database and the active conformation of the C-terminal kinase domain of MSK1 (PDB id 3KN) as the receptor structure to identify chrysin and its derivative, compound 69407, as inhibitors of MSK1. Compared with chrysin, compound 69407 more strongly inhibited proliferation and 12-<I>O</I>-tetradecanoylphorbol-13-acetate (TPA)-induced neoplastic transformation of JB6 P+ cells with lower cytotoxicity. Western blot data demonstrated that compound 69407 suppressed phosphorylation of the MSK1 downstream effector histone H3 in intact cells. Knocking down the expression of MSK1 effectively reduced the sensitivity of JB6 P+ cells to compound 69407. Moreover, topical treatment with compound 69407 before TPA application significantly reduced papilloma development in terms of number and size in a two-stage mouse skin carcinogenesis model. The reduction in papilloma development was accompanied by the inhibition of histone H3 phosphorylation at Ser10 in tumors extracted from mouse skin. The results indicated that compound 69407 exerts inhibitory effects on skin tumorigenesis by directly binding with MSK1 and attenuates the MSK1/histone H3 signaling pathway, which makes it an ideal chemopreventive agent against skin cancer. <I>Cancer Prev Res; 7(1); 74–85. ©2013 AACR</I>.</P>
Lee, Hansol,Lee, Joonsung,Joe, Eunhae,Yang, Seungwook,Choi, Young-suk,Wang, Eunkyung,Song, Ho-Taek,Kim, Dong-Hyun Korean Society of Magnetic Resonance in Medicine 2015 Investigative Magnetic Resonance Imaging Vol.19 No.4
Purpose: For a single time-point hyperpolarized $^{13}C$ magnetic resonance spectroscopy imaging (MRSI) of animal models, scan-time window after injecting substrates is critical in terms of signal-to-noise ratio (SNR) of downstream metabolites. Pre-scans of time-resolved magnetic resonance spectroscopy (MRS) can be performed to determine the scan-time window. In this study, based on two-site exchange model, protocol-specific simulation approaches were developed for $^{13}C$ MRSI and the optimal scan-time window was determined to maximize the SNR of downstream metabolites. Materials and Methods: The arterial input function and conversion rate constant from injected substrates (pyruvate) to downstream metabolite (lactate) were precalibrated, based on pre-scans of time-resolved MRS. MRSI was simulated using two-site exchange model with considerations of scan parameters of MRSI. Optimal scan-time window for mapping lactate was chosen from simulated lactate intensity maps. The performance was validated by multiple in vivo experiments of BALB/C nude mice with MDA-MB-231 breast tumor cells. As a comparison, MRSI were performed with other scan-time windows simply chosen from the lactate signal intensities of pre-scan time-resolved MRS. Results: The optimal scan timing for our animal models was determined by simulation, and was found to be 15 s after injection of the pyruvate. Compared to the simple approach, we observed that the lactate peak signal to noise ratio (PSNR) was increased by 230%. Conclusion: Optimal scan timing to measure downstream metabolites using hyperpolarized $^{13}C$ MRSI can be determined by the proposed protocol-specific simulation approaches.
최종명 ( Jong-myung Choi ),문희성 ( Heesung Moon ),기지훈 ( Jihoon Ki ),박준성 ( Joonsung Park ) 한국정보처리학회 2007 한국정보처리학회 학술대회논문집 Vol.14 No.1
컨텍스트 인지 시스템의 중요성이 커지면서 이러한 시스템을 효과적으로 개발하기 위한 요구가 증대 되고 있다. 본 논문에서는 컨텍스트 인지 시스템의 요구 사항을 파악하기 위해 컨텍스트 정보, 컨텍스트 서비스의 개념을 정의하고, 컨텍스트를 중심으로 시스템 요구 사항을 파악하는 방법을 소개한다.
Joe, Eunhae,Lee, Joonsung,Lee, Hansol,Yang, Seungwook,Choi, Young-Suk,Wang, Eunkyung,Song, Ho-Taek,Kim, Dong-Hyun Korean Society of Magnetic Resonance in Medicine 2017 Investigative Magnetic Resonance Imaging Vol.21 No.1
Purpose: To investigate the exchange and redistribution of hyperpolarized $^{13}C$ metabolites between different pools by temporally analyzing the relative fraction of dual $T_2{^*}$ components of hyperpolarized $^{13}C$ metabolites. Materials and Methods: A dual exponential decay analysis of $T_2{^*}$ is performed for [1-$^{13}C$] pyruvate and [1-$^{13}C$] lactate using nonspatially resolved dynamic $^{13}C$ MR spectroscopy from mice brains with tumors (n = 3) and without (n = 4) tumors. The values of shorter and longer $T_2{^*}$ components are explored when fitted from averaged spectrum and temporal variations of their fractions. Results: The $T_2{^*}$ values were not significantly different between the tumor and control groups, but the fraction of longer $T_2{^*}$ [1-$^{13}C$] lactate components was more than 10% in the tumor group over that of the controls (P < 0.1). The fraction of shorter $T_2{^*}$ components of [1-$^{13}C$] pyruvate showed an increasing tendency while that of the [1-$^{13}C$] lactate was decreasing over time. The slopes of the changing fraction were steeper for the tumor group than the controls, especially for lactate (P < 0.01). In both pyruvate and lactate, the fraction of the shorter $T_2{^*}$ component was always greater than the longer $T_2{^*}$ component over time. Conclusion: The exchange and redistribution of pyruvate and lactate between different pools was investigated by dual component analysis of the free induction decay signal from hyperpolarized $^{13}C$ experiments. Tumor and control groups showed differences in their fractions rather than the values of longer and shorter $T_2{^*}$ components. Fraction changing dynamics may provide an aspect for extravasation and membrane transport of pyruvate and lactate, and will be useful to determine the appropriate time window for acquisition of hyperpolarized $^{13}C$ images.