• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1313-1320
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• 2005

Stenosed coronary artery may play an important role in various coronary heart diseases. However, it has not been known how much stenosed coronary artery affects coronary circulation system, quantitatively. The present study developed a mathematical model for microcirculation in the left common coronary artery (LCCA) with adopting a previously measured morphological data and mechanical properties of the coronary vessels. We examine the effect of percent diameter stenosis on blood flow rate and shear stress for two cases. Case I comprised of one-stenosed element at $10^{th}$ order ($\%$ diameter stenosis are 10, 30, and 50, respectively). Case II consisted of completely occluded element at $10^{th}$ order (number of occluded elements are 0, 1, and 2 out of 8, respectively). As the level of stenosis becomes severe, the shear stress increases significantly but the flow rate reduction was relatively small. However, for the occluded case, there was linearly proportional reduction of flow rate according to number of occluded elements. Either such high shear stress associated with coronary artery stenosis or reduced flow rate due to occlusion may cause atherosclerosis and myocardial ischemia.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권2호
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• pp.71-84
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• 2015

A low-profile flow sensor has been designed, fabricated, and characterized to demonstrate the feasibility for monitoring hemodynamics in cerebral aneurysm. The prototype device is composed of three micro-membranes ($500-{\mu}m$-thick polyurethane film with $6-{\mu}m$-thick layers of nitinol above and below). A novel super-hydrophilic surface treatment offers excellent hemocompatibility for the thin nitinol electrode. A computational study of the deformable mechanics optimizes the design of the flow sensor and the analysis of computational fluid dynamics estimates the flow and pressure profiles within the simulated aneurysm sac. Experimental studies demonstrate the feasibility of the device to monitor intra-aneurysmal hemodynamics in a blood vessel. The mechanical compression test shows the linear relationship between the applied force and the measured capacitance change. Analytical calculation of the resonant frequency shift due to the compression force agrees well with the experimental results. The results have the potential to address important unmet needs in wireless monitoring of intra-aneurysm hemodynamic quiescence.

• The Korean Journal of Physiology and Pharmacology
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• 제23권5호
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• pp.329-334
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• 2019

Diabetes is associated with an increased risk of cardiovascular complications. Dipeptidyl peptidase-4 (DPP-IV) inhibitors are used clinically to reduce high blood glucose levels as an antidiabetic agent. However, the effect of the DPP-IV inhibitor gemigliptin on ischemia/reperfusion (I/R)-induced myocardial injury and hypertension is unknown. In this study, we assessed the effects and mechanisms of gemigliptin in rat models of myocardial I/R injury and spontaneous hypertension. Gemigliptin (20 and 100 mg/kg/d) or vehicle was administered intragastrically to Sprague-Dawley rats for 4 weeks before induction of I/R injury. Gemigliptin exerted a preventive effect on I/R injury by improving hemodynamic function and reducing infarct size compared to the vehicle control group. Moreover, administration of gemigliptin (0.03% and 0.15%) powder in food for 4 weeks reversed hypertrophy and improved diastolic function in spontaneously hypertensive rats. We report here a novel effect of the gemigliptin on I/R injury and hypertension.

• Communications for Statistical Applications and Methods
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• 제28권4호
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• pp.339-350
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• 2021

In medical research, the risk factors associated with human diseases need to be identified to predict the incidence rate and determine the treatment plan. Logistic regression analysis is primarily used in order to select risk factors. However, individuals who are unfamiliar with statistics outcomes have trouble using these methods. In this study, we develop a nomogram that graphically represents the numerical association between the disease and risk factors in order to identify the risk factors for delirium and to interpret and use the results more effectively. By using the logistic regression model, we identify risk factors related to delirium, construct a nomogram and predict incidence rates. Additionally, we verify the developed nomogram using a receiver operation characteristics (ROC) curve and calibration plot. Nursing home, stroke/epilepsy, metabolic abnormality, hemodynamic instability, and analgesics were selected as risk factors. The validation results of the nomogram, built with the factors of training set and the test set of the AUC showed a statistically significant determination of 0.893 and 0.717, respectively. As a result of drawing the calibration plot, the coefficient of determination was 0.820. By using the nomogram developed in this paper, health professionals can easily predict the incidence rate of delirium for individual patients. Based on this information, the nomogram could be used as a useful tool to establish an individual's treatment plan.

• 한국임상수의학회지
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• 제29권3호
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• pp.203-206
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• 2012

심부전의 치료는 심방의 용적 과부하를 줄이기 위한 이뇨제, 심실 압력 과부하를 줄이기 위한 혈관확장제, 심근의 수축력을 향상시키기 위한 강심제 치료로 이루어진다. 이 중 이뇨제가 개의 심부전 조절에서 가장 중요하다. 하지만 장기간의 이뇨제 사용으로 급성 신부전이나 전해질 이상과 같은 부작용이 발생할 수 있다. 따라서 이 연구는 개에서 부작용이 적으면서 더 나은 이뇨효과를 가지는 생약성분의 이뇨제를 찾기 위해 설계되었다. 5마리의 건강한 개를 대상으로 한 예비실험에서 목통(Akebia quinata Decaisne) 추출물은 경도에서 중등도의 이뇨효과(furosemide 2 mg/kg 용량 효과의 0.3-0.5배의 효력)를 보였으며 혈청화학 수치와 전해질 변동은 거의 없었다. 실험 개체 수가 적고 기간이 충분하지 않지만 이 실험을 통해 심부전 환자에서 furosemide의 사용량을 줄이거나 대체할 수 있는 생약성분의 이뇨제 성분을 발굴하였다.

• Journal of Trauma and Injury
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• 제34권2호
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• pp.81-86
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• 2021

Purpose: This study investigated the clinical outcomes of trauma patients with blunt thoracic aortic injuries at a single institution. Methods: During the study period, 9,501 patients with traumatic aortic injuries presented to Trauma Center of Gil Medical Center. Among them, 1,594 patients had severe trauma, with an Injury Severity Score (ISS) of >15. Demographics, physiological data, injury mechanism, hemodynamic parameters associated with the thoracic injury according to chest computed tomography (CT) findings, the timing of the intervention, and clinical outcomes were reviewed. Results: Twenty-eight patients had blunt aortic injuries (75% male, mean age, 45.9±16.3 years). The majority (82.1%, n=23/28) of these patients were involved in traffic accidents. The median ISS was 35.0 (interquartile range 21.0-41.0). The injuries were found in the ascending aorta (n=1, 3.6%) aortic arch (n=8, 28.6%) aortic isthmus (n=18, 64.3%), and descending aorta (n=1, 3.6%). The severity of aortic injuries on chest CT was categorized as intramural hematoma (n=1, 3.6%), dissection (n=3, 10.7%), transection (n=9, 32.2%), pseudoaneurysm (n=12, 42.8%), and rupture (n=3, 10.7%). Endovascular repair was performed in 71.4% of patients (45% within 24 hours), and two patients received surgical management. The mortality rate was 25% (n=7). Conclusions: Traumatic thoracic aortic injuries are life-threatening. In our experience, however, if there is no rupture and extravasation from an aortic injury, resuscitation and stabilization of vital signs are more important than an intervention for an aortic injury in patients with multiple traumas. Further study is required to optimize the timing of the intervention and explore management strategies for blunt thoracic aortic injuries in severe trauma patients needing resuscitation.

• 센서학회지
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• 제22권1호
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• pp.38-43
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• 2013

In this study, the artery's compliance model and the pulsation waveform model was proposed to estimate blood pressure without applying HPF (High Pass Filter) on signal measured by the oscillometric method. The method proposed in the study considered two ways of estimating blood pressure. The first method of estimating blood pressure is by comparing and analyzing changes in pulsation waveform's dicrotic notch region during each cardiac period. The second method is by comparing and analyzing morphological changes in the pulsation waveform during each cardiac period, which occur in response to the change in pressure applied on the cuff. To implement these methods, we proposed the compliance model and the pulsation waveform model of the artery based on hemodynamic theory, and then conducted various simulations. The artery model presented in this study only took artery's compliance into account. Then, a pulsation waveform model was suggested, which uses characteristic changes in the pulsation waveform to estimate blood pressure. In addition, characteristic changes were observed in arterial volume by applying artery's pulsation waveform to the compliance model. The pulsation waveform model was suggested to estimate blood pressure using characteristic changes of the pulsation waveform in the arteries. This model was composed of the sum of sine waves and a Fourier's series in combination form up to 10th harmonics components of the sinusoidal waveform. Then characteristic of arterial volume change was observed by inputting pulsation waveform into the compliance model. The characteristic changes were also observed in the pulsation waveform by mapping the arterial volume change in accordance with applied cuff's pressure change to the pulsation waveform's change according to applied pressure changes by cuff. The systolic and diastolic blood pressures were estimated by applying positional change of pulsation waveform's dicrotic notch region.

• Journal of Ginseng Research
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• 제44권3호
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• pp.483-489
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• 2020

Background: Korean Red Ginseng (KRG) has been known to possess many ginsenosides. These ginsenosides are used for curing cardiovascular problems. The present study show the protective potential of KRG against doxorubicin (DOX)-induced myocardial dysfunction, by assessing electrocardiographic, hemodynamic, and biochemical parameters and histopathological findings. Methods: Animals were fed a standard chow and adjusted to their environment for 3 days before the experiments. Next, the rats were equally divided into five groups (n = 9, each group). The animals were administered with KRG (250 and 500 mg/kg) for 10 days and injected with DOX (20 mg/kg, subcutaneously, twice at a 24-h interval) on the 8th and 9th day. Electrocardiography and echocardiography were performed to study hemodynamics. Plasma levels of superoxide dismutase, catalase, glutathione peroxidase, and malondialdehyde were measured. In addition, the dose of troponin I and activity of myeloperoxidase in serum and cardiac tissue were analyzed, and the histopathological findings were evaluated using light microscopy. Results: Administration of KRG at a dose of 250 and 500 mg/kg recovered electrocardiographic changes, ejection fraction, fractional shortening, left ventricular systolic pressure, the maximal rate of change in left ventricle contraction (-dP/dt_max), and left ventricle relaxation (-dP/dt_max). In addition, KRG treatment significantly normalized the oxidative stress markers in plasma, dose dependently. In addition, the values of troponin I and myeloperoxidase were ameliorated by KRG treatment, dose dependently. And, KRG treatment showed better histopathological findings when compared with the DOX control group. Conclusion: These mean that KRG mitigates myocardial damage by modulating the hemodynamics, histopathological abnormality, and oxidative stress related to DOX-induced cardiomyopathy in rats. The results of the present study show protective effects of KRG on cardiac toxicity.

• Journal of Trauma and Injury
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• 제29권1호
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• pp.8-13
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• 2016

Purpose: Specialized general trauma surgeons play an important role in the care of trauma patients. Hemoperitoneum is a severe, but representative, condition following a life-threatened trauma. The objective of this study was to compare the outcomes for polytrauma patients with hemoperitoneum between the periods during which a trauma surgeon was available and that unavailable. Methods: Thirty-one trauma patients with hemoperitoneum who were treated at Korea University Guro Hospital over a period of 4 years were included in this study, and their case records were analyzed retrospectively. The patients were divided into two groups, the 2011 and 2012 group and the 2013 and 2014 group corresponding, respectively, to the periods that a trauma surgeon was not and was working. Vital signs on admission, scores on the injury severity scale and, Glasgow coma scale, elapsed time to diagnostic, and therapeutic, and/or operative interventions were studied. The effects on intensive care unit and hospital lengths of stay, as well as mortality, were also studied. Results: The study population consisted of 16 and 15 patients in group 1 and 2, respectively. The patients in both groups had six unstable hemodynamic on admission. The time to the main procedure (intervention, operation etc.) was longer during the periods when a trauma surgeon was not working than it was during the period when working. This difference did not reached statistical significance. The mortality rates for the two groups were not statistically different either (18.75% vs 26.67%; p=0.928). Conclusion: Having at least one specialized general trauma surgeon on duty may reduce the time to intervention and surgery for severe trauma patients with hemoperitoneum, but appears to have no effect on the mortality rates. In conclusion, having only one trauma surgeon on duty does not improve the quality of care for trauma patients.

• 한국산학기술학회논문지
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• 제14권5호
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• pp.2322-2328
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• 2013

본 연구는 2011년 8월 16일부터 2012년 7월 11일 사이에 고위 척추마취를 겪는 환자에서 나이에 따른 진정정도의 차이를 호흡기 및 순환기 생체징후의 변화와 함께 마취심도감시장치를 이용하여 객관적으로 알아보고자 하였다. 대상자는 하지나 하복부 수술을 시행할 예정인 20세에서 80세 사이의 성인 60명으로 하였으며, 나이에 따라 20세에서 50세 사이, 51세에서 80세 사이의 환자 군으로 나누었다. 두 그룹은 각각 30명의 환자를 대상으로 하였다. 두 군 모두에서 마취심도수치는 수술 전에 비해 낮게 나왔다. 수술 중 가장 낮은 마취심도수치는 노인 군에서 젊은이 군에 비해 낮았다. 가장 낮은 마취심도수치와 나이는 음의 상관관계를 보여주었다. 노인 군은 젊은이 군에 비해 수술 중 90% 이하의 낮은 산소포화도를 가진 환자수도 많았다. 고위 척추마취 하에서 노인 환자들은 젊은이에 비해 증가된 저산소혈증과 함께 깊은 진정 효과를 보였다.