• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.6
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• pp.1546-1551
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• 2005

This Study was designed to investigate the effects of Nelumbinis Rhizomatis Nodus (NRN) on the change of cerebral hemodynamics [regional cerebral blood flow (rCBF), pial arterial diameter (PAD) and mean arterial blood pressure (MABP)] in normal and cerebral ischemic rats. And, this study was designed to investigate the inhibition of lactate dehydrogenase activity in neuronal cells The results were as follows NRN significantly increased rCBF and PAD in a dose-dependent manner, and NRN increased MABP in a dose-dependent manner. This results suggested that NRN significantly increased rCBF by dilating PAD. Both rCBF and PAD were significantly and stably increased by NRN (10 mg/kg, i.p.) during the period of cerebral reperfusion, which contrasted with the findings of rapid and marked increase in control group. NRN significantly inhibited lactate dehydrogenase activity in neuronal cells. This results suggested that NRN prevented the neuronal death. It is suggested that NRN had an anti-ischemic effect through the improvement of cerebral hemodynamics and inhibitive effect on the brain damage.

• The Korean Journal of Pharmacology
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• v.16 no.1 s.26
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• pp.15-24
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• 1980

As it has been reported that opioids such as morphine and methionine-enkephalin induced antidiuresis and antinatriuresis along with decrease in renal hemodynamics when given intracerebroventricularly(ivt), the renal action of ivt naloxone, a pure antagonist of morphine, and its influence upon the morphine action were investigated in this study. Less than $0.3{\mu}M/kg$ naloxone ivt did not change renal funtion. $1{\mu}M/kg$ ivt tended to, increase urine flow rate and induce transient natriuresis. $3{\mu}M/kg$ ivt produced transient: natriuresis. $3{\mu}M/kg$ ivt produced marked diuresis and natriuresis without any changes of renal hemodynamics. $10{\mu}M/kg$ ivt produced significant increases of urine flow rate and excretion of sodium without any changes of renal hemodynamics. Morphine $0.03{\mu}M/kg$ ivt produced marked decrement in renal hemodynamics along with decreases of water and sodium excretion, as previously shown by Kang. These effects of ivt morphine were completely abolished by the pretreatment with $0.3{\mu}M/kg$ naloxone. These observations provide further evidence that opiate receptors and endorphins in the brain might play an important role in the center-mediated regulation of the renal function in the rabbit.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.1
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• pp.104-110
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• 2002

Citri Reticulatae Viride Pericarpium extract(CRVP) have been used in oriental medicine for many centuries as a therapeutic agent for Soothing the liver and regulating the circulation of qi(疏肝理氣), and promoting digestion and removing stagnated food(消積化滯). The effects of CRVP on the vascular system is not known. The purpose of this Study was to investigate the effects of CRVP on the pial arterial diameter and regional cerebral blood flow(rCBF) in normal rats and ischemic cerebrovascular pathologic model rats. The changes in rCBF was determinated by Laser-Doppler Flowmetry(LDF), and the changes in pial arterial diameter were determinated by video microscopy methods and video analyzer. The results were as follows ; 1. Pial arterial diameter was significantly increased by CRVP in a dose-dependent manner. 2. Pretreatment with L-NNA significantly inhibited CRVP induced increased rCBF and pial arterial diameter. 3. Both the methylene chloride fraction and the hexane fraction of CRVP dose-dependently improved the altered cerebral hemodynamics of cerebral ischemic animal by increasing rCBF. 4. Pretreatment with L-NNA and indomethacin significantly inhibited CRVP(MC) induced increased rCBF. 5. Pretreatment with L-NNA and indomethacin significantly inhibited CRVP(hexane) induced increased rCBF. 6. Pretreatment with CRVP maredly stabilized the changes rCBF and pial arterial diameter during the period of cerebral reperusion. In conclusion, CRVP causes a diverse response of rCBF and pial arterial diameter, and CRVP dose-dependently improved the altered cerebral hemodynamics of cerebral ischemic animal by increasing rCBF and pial arterial diameter. These results suggest that the improvement of cerebral hemodynamics is also mediated by nitric oxide synthase and cyclooxygenase.

• Annals of Clinical Neurophysiology
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• v.1 no.1
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• pp.64-69
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• 1999

Background : Syncope was defined as transient loss of consciousness and postural tone. The mechanisms of changes in cerebral hemodynamics during syncope have not been fully evaluated. Transcranial Doppler Ultrasonography can continuously monitor the changes in cerebral hemodynamics during head-up tilt (HUT). TCD could reveal the different patterns of changes in cerebral hemodynamics during syncope. Syncope without hypotension or bradycardia could be detected by TCD. We investigated the changes in cerebral blood flow velocity during HUT using TCD in 33 patients with a history of recurrent syncope or presyncope of unknown origin. Methods & Results : The positive responses were defined as presyncope or syncope with hypotension, bradycardia, or both. During HUT without isoproterenol infusion, there were a $86{\pm}23%$ drop in DV and a $41{\pm}34%$ drop in SV in 5 patients with positive reponses, and mean changes in those were less than 10% in patients with negative reponses (p=.00, p=.00). During HUT with isoproterenol infusion, TCD showed a $80{\pm}18%$ drop in diastolic velocity in 14 patients with positive reponses, and a $47{\pm}10%$ drop in that in patients with negative reponses (p=.00), however the change in systolic velocity did not differ. TCD showed three patterns during positive responses; loss of all flow, loss of end diastolic flow, and a decrease in diastolic velocity. Loss of consciousness occurred in the patients with loss of all flow or end-diastolic flow during positive reponses. Conclusions : TCD shows different patterns of changes in cerebral hemodynamics during HUT. TCD can be used to investigate the pathophysiology of neurocardiogenic syncope.

• Biomedical Science Letters
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• v.11 no.3
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• pp.397-405
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• 2005

Noise may cause damage of the auditory system, hypertension, and cardiovascular disease. However, we haven't the data enough to be available for understanding various effects of noise on the human body. The current study was prospectively designed to investigate the changes of the cardiac factors and cerebral hemodynamics following a transient exposure to noise in young people. 80 subjects (mean aged $23.45\pm2.40$ years) participated in this experiment and were exposed to excavator-noise with 90 decibels for 15 minutes using ear-phone. Cardiac factors such as heart rate (HR), blood pressure (BP) and heart rate-systolic pressure product (RPP), and cerebral hemodynamics such as mean blood flow velocities (Vm), pulsatility indexes (PI), resistance indexes (RI) and mean blood flow velocities at breathing-hold (Vh) in the middle (MCA), anterior (ACA) and posterior cerebral arteries (PCA) were measured before (baseline) and during the noise-exposure. Although there were individual differences in above mentioned parameters, HR, systolic and diastolic BP, RPP, MCA-Vm, MCA-PI, MCA-RI, ACA-Vm, ACA-PI, ACA-RI, PCA-Vm, PCA-PI, and PCA-RI during the noise-exposure decreased compared with the baselines (P<0.05 or P<0.01), The findings of the present study suggest that a transient exposure to excavator-noise at rest causes changes in the cardiac factors and cerebral hemodynamics with individual differences. Further studies need to be carried out for clarifying the effects of longer exposure and combined mental activity with noise exposure.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.382-392
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• 2023

Objective : The use of indocyanine green videoangiography (ICG-VA) to assess blood flow in the brain during cerebrovascular surgery has been increasing. Clinical studies on ICG-VA have predominantly focused on qualitative analysis. However, quantitative analysis numerical modelling for time profiling enables a more accurate evaluation of blood flow kinetics. In this study, we established a multiple exponential modified Gaussian (multi-EMG) model for quantitative ICG-VA to understand accurately the status of cerebral hemodynamics. Methods : We obtained clinical data of cerebral blood flow acquired the quantitative analysis ICG-VA during cerebrovascular surgery. Varied asymmetric peak functions were compared to find the most matching function form with clinical data by using a nonlinear regression algorithm. To verify the result of the nonlinear regression, the mode function was applied to various types of data. Results : The proposed multi-EMG model is well fitted to the clinical data. Because the primary parameters-growth and decay rates, and peak center and heights-of the model are characteristics of model function, they provide accurate reference values for assessing cerebral hemodynamics in various conditions. In addition, the primary parameters can be estimated on the curves with partially missed data. The accuracy of the model estimation was verified by a repeated curve fitting method using manipulation of missing data. Conclusion : The multi-EMG model can possibly serve as a universal model for cerebral hemodynamics in a comparison with other asymmetric peak functions. According to the results, the model can be helpful for clinical research assessment of cerebrovascular hemodynamics in a clinical setting.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.214-220
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• 2010

This article described that a high Reynolds number version of a turbulence model was modified by using drag reduction to analyze the turbulent flows of non-Newtonian fluid with visco-elastic viscosity and it was applied hemodynamics which was representative of visco-elastic fluid. The turbulence characteristics of visco-elastic fluid was expanded viscous sublayer region and buffer layer region by drag reduction phenomenon and also Newtonian turbulence models does not predict because viscosity was related with shear rate of fluid flow. Hence numerical simulation using a modified turbulence model was conducted under the same conditions that were applied to obtain the experiment results and previous turbulence models and then the numerical investigation of turbulent blood flow in the stenosed artery bifurcation under periodic acceleration of the human body.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1930-1935
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• 2003

The aim of this study is to apply engineering modeling tools to examine hemodynamics such as blood flow patterns or shear stress distributions, in order to determine the link between hemodynamics and cerebral aneurysms. Image-Based Simulation is used to analyze the realistic middle cerebral artery constructed from computed tomography raw data. As a result of simulation, high wall shear stress is appeared at the bifurcated region. And existence of the recirculation flow at the inlet of bifurcation($D_2$) is predict to affect at the development of the cerebral aneurysm.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.723-724
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• 2002

Computational modeling is presented to investigate the hemodynamics of coronary circulation for the cardiac arrest model during the operation of an ECLS called T-PLS. A lumped parameter model is utilized to delineate the hemodynamics of coronary circulation. For verification of the present method, we compute the coronary circulation for normal case and compare those results with the existing data. Numerical results on the cardiac arrest model show that T-PLS can increase LAD flow significantly.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1521-1529
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• 1998

The objective of this study is to investigate the effects of the hemodynamics on the morphological changes of the human endothelial cells due to the blood flow by in vitro experiment and computer simulation. The morphological changes of the endothelial cells due to the t10w shear stress were observed in the laminar t10w chamber as a function of the exposure time. The observed shapes of the endothelial cells are used to the model shapes of the endothelial cells for numerical study and the pressure and the wall shear stress variations around the endothelial cells are calculated from the numerical results. The endothelial cells elongate along the t10w direction and lessen their heights in the flow field to reduce the pressure and the wall shear stress on the surface.