• 대한의용생체공학회:의공학회지
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• 제36권6호
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• pp.264-270
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• 2015

A mock circulatory loop system has been developed to construct a simulator for trainees in cardiopulmonary bypass systems or to simulate a test environment for cardiac-assist devices. This paper proposes a computerized mock circulatory loop system whose node is modularized by using a servo control flow regulator to simulate dynamic change of the hemodynamic status. To observe the effect of time-varying resistance, one with hemodynamic properties, the proposed system replicates the planned cross-sectional areas of the outlet of a ventricular assist device in terms of voltage input of a servo valve. The experiment is performed (1) for steady-input commands of selected area sizes and (2) for dynamic commands such as monotonous increase and decrease, and oscillatory functions of the voltage input, and a computer program based on LabVIEW (National Instruments, Austin, USA) processes every measured data and control command to the servo valve. The results show that the pressure and flow at the target points with respect to time-varying resistance match intuitive estimation: the pressure at the outlet and the pressure drop between both sides of the valve increased and the flow at the outlet decreased for increased resistance.

• Journal of Hospice and Palliative Care
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• 제26권3호
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• pp.101-111
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• 2023

Purpose: This study aimed to identify levels of perception and performance of end-oflife care among nurses and to investigate correlations between perception and performance. Methods: This cross-sectional descriptive survey included 321 nurses from a tertiary hospital in Seoul, Korea. The participants had at least 6 months of work experience and had been involved in end-of-life care at least once, in either ward or intensive care unit settings. A structured questionnaire was utilized to assess their perception and performance of endof-life care. Results: The mean score for perception of end-of-life care was 3.23±0.34, while the score for performance of end-of-life care was 3.08±0.34. There was a significant positive correlation between nurses' perception of end-of-life care and their performance in this area (r=0.78, P<0.001). Conclusion: It is necessary to change perceptions regarding end-of-life care and to develop systematic and standardized education programs including content such as assessing the hydration status of dying patients, evaluating mental aspects such as suicidal ideation, and providing spiritual care for nurses working in end-of-life departments.

• Nutrition Research and Practice
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• 제1권2호
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• pp.143-149
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• 2007

Inadequate dietary intakes and poor health behaviors are of concern among rural residents in Korea. This study is conducted to compare dietary intakes, dietary diversity score (DDS), mean nutrient adequacy ratio (MAR) and health related behaviors by rural, factory and urban areas in Asan. A total of 930 adults (351 men and 579 women) were interviewed to assess social economic status (SES), health related behaviors and food intakes by a 24-hour recall method. Mean age was 61.5 years with men being older (64.8 years) than women (59.3 years, p<0.001). Men in the factory area were older than rural or urban men while urban women were the youngest. Education and income of urban residents were higher than other area residents. There were more current drinkers in urban area while smoking status was not different by regions. Physical activity was significantly higher in rural or factory areas, whilst urban residents exercised more often (p<0.05). Rural or factory area residents considered themselves less healthy than others while perceived stress was lower than urban residents. Energy intakes were higher in urban residents or in men, however, after SES was controlled, energy intake did not show any differences. Energy-adjusted nutrient intakes were significantly higher in the urban area (p<0.05) for most nutrients except for carbohydrate, niacin, folic acid, vitamin $B_6$, iron and fiber. Sodium intake was higher in factory area than in other areas after SES was controlled. DDS of rural men and MAR of both men and women in the rural area were significantly lower when SES was controlled. In conclusion, dietary intakes, diversity, adequacy and perceived health were poor in the rural area, although other health behaviors such as drinking and perceived stress were better than in the urban area. In order to improve perceived health of rural residents, good nutrition and exercise education programs are recommended.

• Ocean and Polar Research
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• 제32권3호
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• pp.203-212
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• 2010

Distribution of organophosphorous pesticides (OPs) was studied from February to September 2008 in the seawater of Asan Bay, Korea. Among the 29 types of OPs detected during the study period, IBP(S-benzyl O,O-diisopropyl phosphorothioate), ranging from <1 ng/l to 377 ng/l, was the most abundant. Other commonly observed OPs concentrations in the study area included diazinon (Diethyl 2-isopropyl-4-methyl-6-pyrimidinyl phosphorothionate; <1~307 ng/l), azinphos ethyl (3,4-Dihydro-4-oxo-3-benzotriazinylmethyl O,O-diethyl phosphorodithioate; <1~1997 ng/l), malathion (1,2-Di(ethoxycarbonyl)ethyl O,Odimethyl phosphordithioates; <1~3013 ng/l), demeton-O (Diethyl 2-(ethylthio)ethyl phosphorothionate; <1~2403 ng/l), and DDVP (2,2-dichlorovinyl dimethyl phosphate; <1~283 ng/l). Seasonal distribution of OPs in seawater is dependent on the OP application period. In August, OPs concentrations were generally decreased with the increased salinity of seawater, implying progressive dilution of pesticides in the estuarine system. OPs were deposited into Asan Bay from Asan and Sabkyo Lakes as well as surrounding tributaries. Ten OPs, including diazinon, were detected in the suspended particles of Asan Bay.

• BMB Reports
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• 제57권3호
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• pp.149-154
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• 2024

The stomach has emerged as a crucial endocrine organ in the regulation of feeding since the discovery of ghrelin. Gut-derived hormones, such as ghrelin and cholecystokinin, can act through the vagus nerve. We previously reported the satiety effect of hypothalamic clusterin, but the impact of peripheral clusterin remains unknown. In this study, we administered clusterin intraperitoneally to mice and observed its ability to suppress fasting-driven food intake. Interestingly, we found its synergism with cholecystokinin and antagonism with ghrelin. These effects were accompanied by increased c-fos immunoreactivity in nucleus tractus solitarius, area postrema, and hypothalamic paraventricular nucleus. Notably, truncal vagotomy abolished this response. The stomach expressed clusterin at high levels among the organs, and gastric clusterin was detected in specific enteroendocrine cells and the submucosal plexus. Gastric clusterin expression decreased after fasting but recovered after 2 hours of refeeding. Furthermore, we confirmed that stomachspecific overexpression of clusterin reduced food intake after overnight fasting. These results suggest that gastric clusterin may function as a gut-derived peptide involved in the regulation of feeding through the gut-brain axis.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제18권3호
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• pp.187-192
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• 2015

Purpose: Measurement of serum ceruloplasmin level is the first step in screening for Wilson's disease (WD). Despite the rarity of WD in the general population, ceruloplasmin levels are routinely measured through hepatitis screening in both adults and children. Herein, we evaluated the diagnostic value of ceruloplasmin for the diagnosis of WD among children with hepatitis. Methods: We retrospectively reviewed data on serum ceruloplasmin levels measured as a serologic marker for patients with hepatitis at Asan Medical Center (Seoul, Korea) between from January 2004 to November 2013. The diagnosis of WD was confirmed by the identification of pathogenic variants in the ATP7B gene. To determine the diagnostic accuracy of ceruloplasmin, receiver operation characteristic (ROC) curves were constructed and the area under curve (AUC) were calculated. Results: Measurements of serum ceruloplasmin were performed in 2,834 children who had hepatitis. Among these, 181 (6.4%) children were diagnosed with WD. The sensitivity, specificity, and accuracy of a ceruloplasmin level of <20 mg/dL in the discrimination of WD were 93.4%, 84.2%, and 84.8%, respectively. In this study, 418 (14.7%) false-positive cases and 12 (0.4%) false-negative cases were noted. Using a ROC curve, a ceruloplasmin level of ${\leq}16.6mg/dL$ showed the highest AUC value (0.956) with a sensitivity of 91.2%, a specificity of 94.9%, and an accuracy of 94.7%. Conclusion: The measurement of serum ceruloplasmin was frequently used for the screening of WD in children, despite a low positive rate. The diagnostic value of ceruloplasmin may be strengthened by adopting a new lower cut-off level.

• Clinical and Experimental Pediatrics
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• 제59권sup1호
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• pp.25-28
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• 2016

Phelan-McDermid syndrome is a rare genetic disorder caused by the terminal or interstitial deletion of the chromosome 22q13.3. Patients with this syndrome usually have global developmental delay, hypotonia, and speech delays. Several putative genes such as the SHANK3, RAB, RABL2B, and IB2 are responsible for the neurological features. This study describes the clinical features and outcomes of Korean patients with Phelan-McDermid syndrome. Two patients showing global developmental delay, hypotonia, and speech delay were diagnosed with Phelan-McDermid syndrome via chromosome analysis, fluorescent in situ hybridization, and multiplex ligation-dependent probe amplification analysis. Brain magnetic resonance imaging of Patients 1 and 2 showed delayed myelination and severe communicating hydrocephalus, respectively. Electroencephalography in patient 2 showed high amplitude spike discharges from the left frontotemporoparietal area, but neither patient developed seizures. Kidney ultrasonography of both the patients revealed multicystic kidney disease and pelviectasis, respectively. Patient 2 experienced recurrent respiratory infections, and chest computed tomography findings demonstrated laryngotracheomalacia and bronchial narrowing. He subsequently died because of heart failure after a ventriculoperitoneal shunt operation at 5 months of age. Patient 1, who is currently 20 months old, has been undergoing rehabilitation therapy. However, global developmental delay was noted, as determines using the Korean Infant and Child Development test, the Denver developmental test, and the Bayley developmental test. This report describes the clinical features, outcomes, and molecular genetic characteristics of two Korean patients with Phelan-McDermid syndrome.

• Korean Journal of Radiology
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• 제22권11호
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• pp.1909-1917
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• 2021

Objective: Muscle quantity and quality can be measured with an automated system on CT. However, the effects of contrast phases on the muscle measurements have not been established, which we aimed to investigate in this study. Materials and Methods: Muscle quantity was measured according to the skeletal muscle area (SMA) measured by a convolutional neural network-based automated system at the L3 level in 89 subjects undergoing multiphasic abdominal CT comprising unenhanced phase, arterial phase, portal venous phase (PVP), or delayed phase imaging. Muscle quality was analyzed using the mean muscle density and the muscle quality map, which comprises normal and low-attenuation muscle areas (NAMA and LAMA, respectively) based on the muscle attenuation threshold. The SMA, mean muscle density, NAMA, and LAMA were compared between PVP and other phases using paired t tests. Bland-Altman analysis was used to evaluate the inter-phase variability between PVP and other phases. Based on the cutoffs for low muscle quantity and quality, the counts of individuals who scored lower than the cutoff values were compared between PVP and other phases. Results: All indices showed significant differences between PVP and other phases (p < 0.001 for all). The SMA, mean muscle density, and NAMA increased during the later phases, whereas LAMA decreased during the later phases. Bland-Altman analysis showed that the mean differences between PVP and other phases ranged -2.1 to 0.3 cm² for SMA, -12.0 to 2.6 cm² for NAMA, and -2.2 to 9.9 cm² for LAMA.The number of patients who were categorized as low muscle quantity did not significant differ between PVP and other phases (p ≥ 0.5), whereas the number of patients with low muscle quality significantly differed (p ≤ 0.002). Conclusion: SMA was less affected by the contrast phases. However, the muscle quality measurements changed with the contrast phases to greater extents and would require a standardization of the contrast phase for reliable measurement.

• Korean Journal of Radiology
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• 제23권4호
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• pp.446-454
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• 2022

Objective: To evaluate whether hyperoxia-induced ΔR₁ (hyperO₂ΔR₁) can accurately identify histological infarction in an acute cerebral stroke model. Materials and Methods: In 18 rats, MRI parameters, including hyperO₂ΔR₁, apparent diffusion coefficient (ADC), cerebral blood flow and volume, and ¹⁸F-fluorodeoxyglucose uptake on PET were measured 2.5, 4.5, and 6.5 hours after a 60-minutes occlusion of the right middle cerebral artery. Histological examination of the brain was performed immediately following the imaging studies. MRI and PET images were co-registered with digitized histological images. The ipsilateral hemisphere was divided into histological infarct (histological cell death), non-infarct ischemic (no cell death but ADC decrease), and nonischemic (no cell death or ADC decrease) areas for comparisons of imaging parameters. The levels of hyperO₂ΔR₁ and ADC were measured voxel-wise from the infarct core to the non-ischemic region. The correlation between areas of hyperO₂ΔR₁-derived infarction and histological cell death was evaluated. Results: HyperO₂ΔR₁ increased only in the infarct area (p ≤ 0.046) compared to the other areas. ADC decreased stepwise from non-ischemic to infarct areas (p = 0.002 at all time points). The other parameters did not show consistent differences among the three areas across the three time points. HyperO₂ΔR₁ sharply declined from the core to the border of the infarct areas, whereas there was no change within the non-infarct areas. A hyperO₂ΔR₁ value of 0.04 s^-1 was considered the criterion to identify histological infarction. ADC increased gradually from the infarct core to the periphery, without a pronounced difference at the border between the infarct and non-infarct areas. Areas of hyperO₂ΔR₁ higher than 0.04 s^-1 on MRI were strongly positively correlated with histological cell death (r = 0.862; p < 0.001). Conclusion: HyperO₂ΔR₁ may be used as an accurate and early (2.5 hours after onset) indicator of histological infarction in acute stroke.

• 대한지하수환경학회지
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• 제5권3호
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• pp.129-140
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• 1998

이 연구는 오염원이 산재해 있는 농촌지역으로 아산지역을, 그리고 공업단지와 주거지역이 위치한 공단지역으로 구로구지역을 연구대상지역으로 선정하여 공단지역과 농촌지역 지하수의 물리.화학적 특성과 오염 양상을 조사하였다. 또한 지하수의 효율적인 이용과 적절한 관리를 위해 지리정보시스템을 구축하고 이를 이용하여 지하수오염과 잠재점오염원의 공간적인 관련성을 규명하였다. 아산지역 지하수는 Ca-HCO$_3$유형의 지하수이며 SiO$_2$와 HCO$_3$함량비가 높은 특징을 보여 물-암석 반응이 지하수 성분을 지배하는 가장 큰 요인임을 보여준다. 구로구지역 지하수는 Ca-HCO$_3$유형의 지하수이며 Cl, NO$_3$및 SO$_4$등 오염물질이 부화되고 SiO$_2$에 비해 Ca 함량비가 더 높게 나타나는 등 다양한 오염원에 의한 영향을 반영하고있다. 아산지역에서는 37.5%(총 40개 중 15개)의 지하수 시료에서 NO$_3$,SO$_4$및 Zn의 함량이 먹는 물 수질 기준을 초과하는 오염현상이 조사되었으며, 대부분이 NO$_3$의 오염이었다. 축산농가 및 공장에 대해 오염영향범위를 조사하기 위해 버퍼링 분석을 실시한 결과 l00 m 거리에 걸쳐 오염의 영향이 미치고 있어 공장 및 축산농가가 지하수 오염의 직접적인 원인임을 확인하였다. 구로구지역에서는 64.7%(총 51개 중 33개)의 지하수 시료에서 NO$_3$, Cl, SO$_4$, Fe 및 Zn의 함량이 음용수 수질기준을 초과하는 오염현상이 확인되었다. NO$_3$오염은 50 m 이상의 심부지하수에서도 관찰되어 이미 심각한 오염현상이 진행되었음을 보여주었다. Cl 오염은 구로동 지역의 50 m 이하 천부지하수에서 관찰되었으나 구로동의 구로공단지역에서는 먹는 물 수질기준 이하의 낮은 함량을 보였다. 구로동지역은 70%, 고척동지역은 42%, 궁동지역은 14%의 지하수 시료에서 오염물질이 먹는 물 수질기준을 초과하는 오염현상이 조사되었다.