• Title/Summary/Keyword: Blood flow rates

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Experimental Study on Cerebral Hemodynamics during Observation of Plants

  • Suda, Ayumu;Lee, Ju-Young;Fujii, Eijiro
    • Proceedings of the Korean Institute of Landscape Architecture Conference
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    • 2007.10b
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    • pp.214-219
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    • 2007
  • Psychological and physiological effects of plants were studied by investigating human responses while observing plants. Eighteen healthy adult male(aged between $19{\sim}25$ years) participated in this study. Semantic differential method(SD method) and multi-channel near-infrared spectroscopy(NIRS) were used to survey verbal and non-verbal response, respectively. Cerebral hemodynamics as a new evaluation index of brain activity was recorded for right brain hemisphere where visual information is mainly delivered. Thirty seconds of cerebral blood flow in forty seven channels were calculated when watching five types of picture images with different rates of hedge against gray block wall; 0:10, 3:7, 5:5, 7:3, 10:0. In the SD results, similar evaluations were found in all subjects. However, the change of cerebral hemodynamics as a non-verbal response varied among subjects. Largely two patterns of hemodynamics change were found with increasing plants rate in picture images; group A showed significant decreases of blood flow volume in many cortical regions, Group B had significant increase of blood flow volume in the occipital region for the scenes seen comparatively more plant. Our findings on the cerebral hemodynamics may indicate that there are two patterns of brain activity during observation of plants; group A in which brain areas associated with visual information and thinking work simultaneously to the visual stimuli; group B in which brain areas associated only with visual information work.

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Influences of Geometric Configurations of Bypass Grafts on Hemodynamics in End-to-Side Anastomosis

  • Choi, Jae-Sung;Hong, Sung-Chul;Kwon, Hyuck-Moon;Suh, Sang-Ho;Lee, Jeong-Sang
    • Journal of Chest Surgery
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    • v.44 no.2
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    • pp.89-98
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    • 2011
  • Background: Although considerable efforts have been made to improve the graft patency in coronary artery bypass surgery, the role of biomechanical factors remains underrecognized. The aim of this study is to investigate the influences of geometric configurations of the bypass graft on hemodynamic characteristics in relation to anastomosis. Materials and Methods: The Numerical analysis focuses on understanding the flow patterns for different values of inlet and distal diameters and graft angles. The Blood flow field is treated as a two-dimensional incompressible laminar flow. A finite volume method is adopted for discretization of the governing equations. The Carreau model is employed as a constitutive equation for blood. In an attempt to obtain the optimal aorto-coronary bypass conditions, the blood flow characteristics are analyzed using in vitro models of the end-to-side anastomotic angles of $45^{\circ}$, $60^{\circ}$ and $90^{\circ}$. To find the optimal graft configurations, the mass flow rates at the outlets of the four models are compared quantitatively. Results: This study finds that Model 3, whose bypass diameter is the same as the inlet diameter of the stenosed coronary artery, delivers the largest amount of blood and the least pressure drop along the arteries. Conclusion: Biomechanical factors are speculated to contribute to the graft patency in coronary artery bypass grafting.

Postprandial Changes in Gastrointestinal Hormones and Hemodynamics after Gastrectomy in Terms of Early Dumping Syndrome

  • Yang, Jun-Young;Lee, Hyuk-Joon;Alzahrani, Fadhel;Choi, Seung Joon;Lee, Woon Kee;Kong, Seong-Ho;Park, Do-Joong;Yang, Han-Kwang
    • Journal of Gastric Cancer
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    • v.20 no.3
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    • pp.256-266
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    • 2020
  • Purpose: This study aimed to examine the early postprandial changes in gastrointestinal (GI) hormones and hemodynamics in terms of early dumping syndrome after gastrectomy for gastric cancer. Materials and Methods: Forty patients who underwent gastrectomy for gastric cancer and 18 controls without previous abdominal surgery were enrolled. Before and 20 minutes after liquid meal ingestion, blood glucose, glucagon-like peptide-1 (GLP-1), and GLP-2 concentrations and superior mesenteric artery (SMA) and renal blood flow were measured. The patients' heart rates were recorded at 5-minute intervals. All subjects were examined for dumping syndrome using a questionnaire based on Sigstad's clinical diagnostic index. Results: The postprandial increases in blood glucose, GLP-1, and GLP-2 levels as well as SMA blood flow and heart rate were greater in patients who underwent gastrectomy than in controls (all P<0.010). Patients who underwent gastrectomy showed a significantly decreased renal blood flow (P<0.001). Among patients who underwent gastrectomy, distal gastrectomy was a significant clinical factor associated with a lower risk of early dumping syndrome than total gastrectomy (hazard ratio, 0.092; 95% confidence interval, 0.013-0.649; P=0.017). Patients who underwent total gastrectomy showed a greater postprandial increase in blood glucose (P<0.001), GLP-1 (P=0.030), and GLP-2 (P=0.002) levels as well as and heart rate (P=0.013) compared to those who underwent distal gastrectomy. Conclusions: Early postprandial changes in GI hormones and hemodynamics were greater in patients who underwent gastrectomy than in controls, especially after total gastrectomy, suggesting that these changes play a crucial role in the pathophysiology of early dumping syndrome.

Red Blood Cell Velocity Field in Rat Mesenteric Arterioles Using Micro PIV Technique

  • Sugii, Y;Nishio, S;Okamoto, K;Nakano, A;Minamiyama, M;Niimi, H
    • International Journal of Vascular Biomedical Engineering
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    • v.1 no.1
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    • pp.24-31
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    • 2003
  • As endothelial cells are subject to flow shear stress, it is important to determine the detailed velocity distribution in microvessels in the study of mechanical interactions between blood and endothelium. This paper describes a velocity field of the arteriole in the rat mesentery using an intravital microscope and high-speed digital video system obtained by a highly accurate PIV technique. Red blood cells (RBCs) velocity distributions with spatial resolutions of $0.8{\times}0.8{\mu}m$ were obtained even near the wall in the center plane of the arteriole. By making ensemble-averaged time-series of velocity distributions, velocity profiles over different cross-sections were calculated for comparison. The shear rate at the vascular wall also evaluated on the basis of the ensemble-averaged profiles. It was shown that the velocity profiles were blunt in the center region of the vessel cross-section while they were steep in the near wall region. The wall shear rates were significantly small, compared with those estimated from the Poiseuille profiles.

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Physiological approach of CADASIL animal model and its predictable implication (CADASIL 동물모델의 생리학적 접근 및 연구적 가치의 예측)

  • Jung, Sung-Cherl;Ko, Eun-A
    • Journal of Medicine and Life Science
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    • v.16 no.3
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    • pp.55-59
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    • 2019
  • Cerebral vessels are functionally and structurally specialized to provide adequate blood flow to brain which shows high metabolic rates. Cerebral hemorrhage or ischemic infarction due to cerebrovascular injury or occlusion can cause the immediate brain damage, and if not treated rapidly, can lead to serious or permanent brain damages, and sometimes life-threatening. Unlike these popular cerebrovascular diseases, there are diseases caused by genetic problems. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is one of them. CADASIL does not show the high incidence, but it is considered to be significantly affected by regional obstructiveness such as islands and therefore, to be an important genetic disease in Jeju. This paper aims to summarize the possibility of animal model research that can provide preclinical data for CADASIL disease research and to evaluate its applicability in future research plans.

A Phase-based Method for Blood Flow Impedance in the Windkessel Model

  • Choi, Joon-Hyuck;Kang, Nam-Lyong;Choi, Sang-Don
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.11 no.3
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    • pp.53-64
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    • 2007
  • Considering a sinusoidally varying blood pressure In left ventricle in Cho - Kensey's Windkessel model, we expressed the impedance elements in terms of the phase differences among the pressure and flow rates in the artery and the peripherical tubes. The relationships were further simplified for the real human cardiac system. We expect that the results would give some valuable information for examination and treatment in oriental medicine as well as in western medicine.

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Blood Flow Rate Estimation using Proximal Isovelocity Surface Area Technique Based on Region-Based Contour Scheme and Surface Subdivision Flow Model (영역기반 윤곽선 기법과 표면 분할 유동모델에 기반한 근위 등속 표면적 기법을 이용한 혈류량 추정)

  • Jin, Kyung-Chan;Cho, Jin-Ho
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.38 no.1
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    • pp.45-52
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    • 2001
  • The proximal isovelocity surface area (PISA) method is an effective way of measuring the regurgitant blood flow rate in the mitral valve. This method defines the modelling required to describe the geometry of the isotach of the PISA. In the normal PISA flow model, the flow rate is calculated assuming that the surface of the isotach is either hemispherical or non-hemispherical numerically. However, this paper evaluated the estimate flow rate using a direct surface subdivision flow model based on the height field after isotach extraction using a region-based scheme. To validate the proposed method, the various PISA flow models were compared using pusatile color Doppler images with flow rates ranging from $30\;cm^3/sec\;to\;60\;cm^3/sec$ flow rate. Whereas the hemispherical flow model had a mean value of $29\;cm^3/sec$ and underestimated the measured flow rate by 35%, the proposed model and non-hemispherical model produced a c;ame mean value of $45\;cm^3/sec$, moreover, both flow models produced a similar pulsatile flow rate.

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A Study of Design of Hollow Fiber Membrane Modules for using in Artificial Lung by the PZT Actuator

  • Kim, Gi-Beum;Kim, Seong-Jong;Hong, Chul-Un;Lee, Yong-Chul;Kim, Min-Ho
    • Journal of Biomedical Engineering Research
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    • v.27 no.4
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    • pp.143-153
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    • 2006
  • The purpose of this work was to assess and quantify the beneficial effects of gas exchange, while testingto the various frequencies of the sinusoidal wave that was excited by the PZT actuator, for patients suffering from acute respiratory distress syndrome (ARDS) or chronic respiratory problems. Also, this paper considered a simulator to design a hollow type artificial lung, and a mathematical model was used to predict a behavior of blood. This simulation was carried out according to the Montecarno's simulation method, anda fourth order Runge-Kutta method was used to solve the equation. The experimental design and procedure are then applied to the construction of a new device to assess the effectiveness of the membrane vibrations. As a result, the vibration method is very effective in the increase of gas transport. The gas exchange efficiency for the vibrating intravascular lung assist device can be increased by emphasizing the following design features: consistent and reproducible fiber geometry, and most importantly, an active means of enhancing convective mixing of water around the hollow fiber membranes. The experimental results showed the effective performance of the vibrating intravascular lung assist device. Also, we concluded that important design parameters were blood flow rates, fiber outer diameter and oxygen pressure drop. Based on the present results, it was believed that the optimal level of blood flow rates was 200$cm^3$/min.

Effects of Dietary Rna and Adenine on Feed Intake and Kidney Weight and Function in Adult Cockerels

  • Kubota, T.;Karasawa, Yutaka
    • Asian-Australasian Journal of Animal Sciences
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    • v.10 no.3
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    • pp.260-264
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    • 1997
  • This study was conducted with adult cockerels to determine whether dietary RNA affects feed intake and renal weight and function, and if the responses are similar to dietary adenine. Chickens were ad libitum fed a RNA diet (100 g/kg) or an adenine diet (9.1 g/kg) for 14 d and catheterized in right jugular vein, hepatic portal vein and both urethers, and saline together with para-amino hippuric acid and sodium thiosulfate was continuously infused into them to evaluate renal functions. Dietary RNA reduced feed intake and body weight, and dietary adenine increased kidney weight expressed as a proportion of body weight (P < 0.05). Feed intake and body weight on the adenine diet and kidney weight on the RNA diet showed similar though non significant tendencies. No calculi were detected in the kidney in chickens fed either the RNA or adenine diets. Plasma inorganic phosphate (IP), Ca and 1,25 $(OH)_2$ vitamin $D_3$ concentrations were increased by dietary RNA and adenine, although the increases of IP and Ca in adenine-fed chickens were not significant. Uric acid and urea concentrations in the blood plasma were unaffected by dietary RNA or adenine. Both dietary RNA and adenine increased renal blood flow rates 3.5-3.7 fold, renal plasma flow rates 3.4-3.7 fold and glomerular filtration rates (GFR) 2.9-3.0 fold (p < 0.01). Clearance of urea, IP and Ca were also enhanced by dietary RNA, but not by dietary adenine. However, neither RNA nor adenine affected uric acid clearance. Only IP clearance was significantly augmented at the glomerular level by dietary RNA (p < 0.05). Glomerular filtration of uric acid, urea, IP and Ca and reabsorption of urea, IP and Ca at the renal tubule were increased by dietary RNA and adenine (p < 0.05), whereas tubular secretion of uric acid was decreased by both dietary treatments. It is concluded that dietary adenine is effective in changing renal function and P and Ca metabolism in chickens.

Intraaneurysmal Blood Flow Changes for the Different Coil Locations (코일 위치에 따른 동맥류 내부 혈류유동의 변화)

  • 이계한;정우원
    • Journal of Biomedical Engineering Research
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    • v.25 no.4
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    • pp.295-300
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    • 2004
  • Coil embolization technique has been used recently to treat cerebral aneurysms. When a giant or a multilobular aneurysm are treated by roils, filling an aneurysm sac completely with coils is difficult and partial blocking of an aneurysm sac is inevitable. Blood flow characteristics, which nay affect the embolization process of an aneurysm sac, are changed by the locations of coils for the Partially blocked aneurysms. Blood flow fields are also influenced by the geometry of a parent vessel. In order to suggest the coil locations effective for aneurysm embolization, the blood flow fields of lateral aneurysm models were analyzed for the different coil locations and parent vessel geometries. Three dimensional pulsatile flow fields are analyzed by numerical methods considering non-Newtonian viscosity characteristics of blood. Flow rate into the aneurysm sac (inflow rate) and wall shear stress, which are suspected as flow dynamic factors influencing aneurysm embolization, are also calculated. Inflow rates were smaller and the low wall shear stress zones were larger in the neck blocked models compared to the dome blocked models. Smaller inflow and larger low wall shear stress zones in the distal neck blocked model imply that the distal neck should be the effective coil locations for aneurysm embolization.