• Journal of the Korean Society for Precision Engineering
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• v.33 no.1
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• pp.69-75
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• 2016

Polydimethylsiloxane (PDMS) is used as a scaffold for cell culture. Because both the stress and strain acting on the substrate and the hemodynamic environment are important for studying mechano-transduction of cellular function, the traction force of the surface of a substrate has been measured using fluorescence images of particle distribution. In this study, deformation of the cross-sectional plane of a PDMS block was measured by correlating particle image distributions to validate the particle image strain measurement technique. Deformation was induced by a cone indentor and a shearing parallel plate. Measured deformations from particle image distributions were in agreement with the results of a computational structure analysis using the finite-element method. This study demonstrates that the particle image correlation method facilitates measurement of deformation of a polymer scaffold in the cross-sectional plane.

• The Korea Journal of Herbology
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• v.20 no.3
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• pp.75-81
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• 2005

Objectives : In brain disorders such as ischemic stroke, the final outcome depends largely on the duration and the degree of the ischemia as well as the susceptibility of various cell types in the affected brain region. In the present study, the effects of Nodus Nelumbinis Rhizomatis Extract(NNRe) were tested for the anti-oxidative action of rCBF. Methods : Regional cerebral blood flow(rCBF) were determined by LDF methods. LDF allows for real time, noninvasive, continuous recordings of local CBF. The LDF method has been widely used to trace hemodynamic changes in the superficial or the deep brain structures in experimental stroke research. Results : NNRe treatment showed no change on rCBF in methylene blue, ODQ and L-NNA pretreated rats. 120 minutes of MCAO and followed reperfusion, 0.1% concentration of NNR treatment improved the altered cerebral hemodynamics of cerebral ischemic by increasing rCBF. Conclusions : The ischemia/reperfusion induced oxidative stress may have contributed to cerebral damage in rats, and the present study provides clear evidences for the beneficial effect of NNR on ischemia/reperfusion induced brain injury.

• Journal of Neurocritical Care
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• v.11 no.2
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• pp.71-80
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• 2018

Nutritional assessment and support are often overlooked in the critically ill due to other urgent priorities. Unlike oxygenation, organ dysfunction, infection, or consciousness, there is no consensus of indicators. Making it difficult to evaluate the effectiveness of an intervention. Nevertheless, appropriate nutritional support in the critically ill has been associated with less morbidity and lower mortality. But, nutritional support has been considered an adjunct, for body weight maintenance and to help patients during the inflammatory phase of illness. Thus, it has been assigned a lower priority, compared to mechanical ventilation or hemodynamic stability. Recent findings have shown that nutritional support may prevent cellular injury due to oxidative stress and help strengthen the immune response. Large-scale randomized trials and clinical guidelines have shown a shift from nutritional support to nutritional therapy, with an emphasis on the importance of protein, minerals, vitamins, and trace elements. Nutrition is also important in neurocritically ill patients. Since there are few studies or recommendations with regard to the neurocritical population, the general recommendations for nutritional support should be applied.

• Journal of Ginseng Research
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• v.44 no.3
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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.

• Childhood Kidney Diseases
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• v.13 no.2
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• pp.99-117
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• 2009

Diabetic nephropathy is a major cause of chronic renal failure in developing countries, and the prevalence rate has markedly increased during the past decade. Diabetic nephropathy shows various specific histological changes not only in the glomeruli but also in the tubulointerstitial region. In the early stage, the effacement of podocyte foot processes and thickened glomerular basement membrane (GBM) is noticed even at the stage of microalbuminuria. Nodular, diffuse, and exudative lesions, so-called diabetic glomerulosclerosis, are well known as glomerular lesions. Interstitial lesions also exhibit fibrosis, edema, and thickened tubular basement membrane. Diabetic nephropathy is considered to be multifactorial in origin with increasing evidence that one of the major pathways involved in the development and progression of diabetic nephropathy as a result of hyperglycemia. Hyperglycemia induces renal damage directly or through hemodynamic alterations, such as, glomerular hyperfiltration, shear stress, and microalbuminuria. Chronic hyperglycemia also induces nonhemodynamic dysregulations, such as, increased production of advanced glycosylation endproducts, oxidative stress, activation of signal pathway, and subsequent various cytokines. Those pathogenic mechanisms resulted in extracellular matrix deposition including mesangial expansion and GBM thickening, glomerular hypertrophy, inflammation, and proteinuria. In this review, recent opinions on the histopathologic changes and pathophysiologic mechanisms leading to initiation and progression of diabetic nephropathy will be introduced.

• Journal of Biomedical Engineering Research
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• v.18 no.2
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• pp.187-196
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• 1997

The three-dimensional flow analysis using the finite volume method is presented to compare the steady flow characteristics of blood with those of blood substitutes such as water and aqueous polymer solution in an idealized double branching model. The model is used to simlllate the region of the abdominal aorta near the celiac and superior mesenteric branches. Apparent viscosities of blood and the aqueous Separan solution are represented as a function of shear rate by the Carreau model, Water and aqueoiu Separan AP-273 500wppm solution are frequently used as blood substitutes in vitro experiments. Water is a typical Newtonian fluid and blood and Separan solution are non-Newtonian fluids. Flow phenomena such as velocity distribution, pressure variation and wall shear stress distribution of water, blood and polymer solution are quite different due to differences of the rheological characteristics of fluids. Flow phenomena of polymer solution are qualitatively similar to those of blood but the phenomena of water are quite different from those of blood and polymer solution. It is recommended that a lion-Newtonian fluid which exhibits very similar rheological behavior to blood be used in vitro experiments. A non-Newtonian fluid whose rheological characteristics are very similar to those of blood should be used to obtain the meaninylll hemodynamic data for blood flow in vitro experiment and by numerical analysis

• Biomedical Science Letters
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• v.19 no.3
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• pp.254-260
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• 2013

The purpose of this study was to survey the effects of Karvonen exercise prescription in coronary artery disease patients reaching age-predicted maximal heart rates with the exercise stress test on hemodynamic responses and cardiorespiratory fitness. The subject group was comprised of acute coronary syndrome (ACS) patients, who were divided into the maximal heart rate (MHR) group that included those who completed the test with their heart rates reaching the number of 220-age and the maximal dyspnea (MD) group that included those who could not continue the test due to respiratory difficulty and were asked to stop the test. Both groups had the exercise stress test before and after the experiment. In the exercise stress test before the experiment, the exercise prescription intensity of Karvonen was set at the target heart rates of 50~85% with a six-week exercise monitoring arrangement. As a result, there were no interactive effects in rest heart rate (RHR) according to time and group, but interactive effects were observed in maximal heart rate (MHR) (P=0.000). Both rest systolic blood pressure (RSBP) and rest diastolic blood pressure (RDBP) had no interactive effects according to time and group. Maximal systolic blood pressure (MSBP) showed significant interactive effects according to time and group (P=0.017). Maximal diastolic blood pressure (MDBP) showed no interactive effects according to time and group, while maximal rate pressure product (MRPP) showed significant interactive effects according to time and group (P=0.003). Maximal time (MT) had no interactive effects according to time and group. $VO_{2max}$ and maximal metabolic equivalent (MMET) showed significant interactive effects according to time and group (P=0.000, P=0.002, respectively), whereas maximal respiratory exchange ratio (MRER) and maximal rating of perceived exertion (MRPE) showed no interactive effects according to time and group. The exercise test that was discontinued as the subjects reached the predicted maximal heart rates considering age did not reach the maximal exercise intensity and accordingly showed low exercise effects when applied to Karvonen exercise prescription intensity. That is, the test should keep going by monitoring cardiac events, MRER and MRPE until the heart rates exceed the predicted MHR by up to 10~12 even after the subject reaches the predicted MHR considering age in the exercise stress test.

• Journal of Yeungnam Medical Science
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• v.14 no.2
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• pp.350-358
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• 1997

We studied the effects of adding a single bolus(500 mg) of sodium thiopental to a continuous infusion of low-dose fentanyl on plasma beta-endorphin immunoreactivity(iBE) responses to cardiopulmonary bypass(CPB) in 28 patients undergoing elective coronary artery bypass grafting or valve procedures. Thiopental was injected just prior to the initiation of CPB. The iBE levels and the hemodynamic indices such, as mean arterial pressure, cardiac output and systemic vascular resistance were measured before CPB, at 30 min and again at 60 min after the initiation of the bypass. The results were as follows. After the initiation of CPB, iBE levels increased at 30 min and 60 min(P=0.006, P=0.004 respectively) in the control group, but not in the thiopental group. There were significant differences in the changes of iBE levels between the groups(F=8.7, G-G=0.002, P=0.001). The hemodynamic indices were similar in both groups. In conclusion, pretreatment with thiopental just before the initiation of CPB prevents the stress-induced beta-endorphin response to CPB.

• The Korean Journal of Pain
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• v.6 no.2
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• pp.231-236
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• 1993

Clonidine, a centrally-acting antihypertensive agent known to reduce central sympathetic outflow and modulate presynaptic transmitter's release, has shown to suppress central noradrenergic hyperactivity induced by immobilization stress in animals, by decreasing the MAC of halothane and the dose of narcotics required to prevent reflex cardiovascular response to noxious stimuli, and to have potent analgesic properties in humans. These characteristics suggest that clonidine might be a useful adjunct to the anesthetic management of patients with preexisting hypertension. Accordingly, we determined the clinical efficacy and safety on analgesia, sedation and hemodynamic stability in the perioperative period. Thirty patients(ASA physical status II-III) with a history of arterial hypertension, scheduled for elective orthopedic surgery were randomly assigned to two groups. We applied CPA-clonidine patch($6.9\;mg/cm^2$, 0.2 mg delivered daily) or placebo patch to each groups, 48 hours prior to induction of anesthesia. Antihypertensive medication was continued until the morning of the scheduled surgery. All patients received premedication of atropine and lorazepam, and induced anesthesia with thiopental and succinylcholine, and maintained with enflurane and 50% nitrous oxide, while sustaining the BP and pulse rate at acceptable range. For the relief of pain postoperatively, diclofenac and fentanyl were administered intramuscularly on demand. The results were as follows: 1) The change of hemodynamic responses in clonidine group was less compared to the placebo group. 2) Intraoperative anesthetic requirement for enflurane in clonidine group were significantly lower than placebo group. 3) Postoperative analgetic requirement in clonidine group were significantly lower than placebo group. In clonidine group, 5 cases out of 15 cases were required no analgetics, and the incidence of administration of additional fentanyl was decreased to 5 cases, comparing with 10 cases in placebo group.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.3
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• pp.192-200
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• 2008

To evaluate the hemodynamic changes and the predictive factors of the clinical outcome in pediatric patients with moyamoya disease, we analyzed pre/post basal/acetazolamide stress brain perfusion SPECT with automated volume of interest (VOIs) method. Methods: Total fifty six (M:F = 33:24, age $6.7{\pm}3.2$ years) pediatric patients with moyamoya disease, who underwent basal/acetazolamide stress brain perfusion SPECT within 6 before and after revascularization surgery (encephalo-duro-arterio-synangiosis (EDAS) with frontal encephalo-galeo-synangiosis (EGS) and EDAS only followed on contralateral hemisphere), and followed-up more than 6 months after post-operative SPECT, were included. A mean follow-up period after post-operative SPECT was $33{\pm}21$ months. Each patient's SPECT image was spatially normalized to Korean template with the SPM2. For the regional count normalization, the count of pons was used as a reference region. The basal/acetazolamide-stressed cerebral blood flow (CBF), the cerebral vascular reserve index (CVRI), and the extent of area with significantly decreased basal/acetazolamide- stressed rCBF than age-matched normal control were evaluated on both medial frontal, frontal, parietal, occipital lobes, and whole brain in each patient's images. The post-operative clinical outcome was assigned as good, poor according to the presence of transient ischemic attacks and/or fixed neurological deficits by pediatric neurosurgeon. Results: In a paired t-test, basal/acetazolamide-stressed rCBF and the CVRI were significantly improved after revascularization (p<0.05). The significant difference in the pre-operative basal/acetazolamide-stressed rCBF and the CVRI between the hemispheres where EDAS with frontal EGS was performed and their contralateral counterparts where EDAS only was done disappeared after operation (p<0.05). In an independent student t-test, the pre-operative basal rCBF in the medial frontal gyrus, the post-operative CVRI in the frontal lobe and the parietal lobe of the hemispheres with EDAS and frontal EGS, the post-operative CVRI, and ${\Delta}CVRI$ showed a significant difference between patients with a good and poor clinical outcome (p<0.05). In a multivariate logistic regression analysis, the ${\Delta}CVRI$ and the post-operative CVRI of medial frontal gyrus on the hemispheres where EDAS with frontal EGS was performed were the significant predictive factors for the clinical outcome (p =0.002, p =0.015), Conclusion: With probabilistic map, we could objectively evaluate pre/post-operative hemodynamic changes of pediatric patients with moyamoya disease. Specifically the post-operative CVRI and the post-operative CVRI of medial frontal gyrus where EDAS with frontal EGS was done were the significant predictive factors for further clinical outcomes.