• International Journal of Vascular Biomedical Engineering
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• v.2 no.2
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• pp.16-26
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• 2004

The object of this study is to develop a mathematical model of the hemodialysis system including the mechanism of solute kinetics, water exchange and also cardiovascular dynamics. The cardiovascular system model used in this study simulates the short-term transient and steady-state hemodynamic responses such as hypotension and disequilibrium syndrome (which are main complications to hemodialysis patients) during hemodialysis. It consists of a 12 lumped-parameter representation of the cardiovascular circulation connected to set-point models of the arterial baroreflexes, a kinetic model (hemodialysis system model) with 3 compartmental body fluids and 2 compartmental solutes. We formulate mathematically this model in terms of an electric analog model. All resistors and most capacitors are assumed to be linear. The control mechanisms are mediated by the information detected from arterial pressoreceptors, and they work on systemic arterial resistance, heart rate, and systemic venous unstressed volume. The hemodialysis model includes the dynamics of urea, creatinine, sodium and potassium in the intracellular and extracellular pools as well as fluid balance equations for the intracellular, interstitial, and plasma volumes. Model parameters are largely based on literature values. We have presented the results on the simulations performed by changing some model parameters with respect to their basal values. In each case, the percentage changes of each compartmental pressure, heart rate (HR), total systemic resistance (TSR), ventricular compliance, zero pressure filling volume and solute concentration profiles are represented during hemodialysis.

• Imaging Science in Dentistry
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• v.46 no.1
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• pp.53-56
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• 2016

$M{\ddot{o}}nckeberg$ sclerosis is a disease of unknown etiology, characterized by dystrophic calcification within the arterial tunica media of the lower extremities leading to reduced arterial compliance. Medial calcinosis does not obstruct the lumina of the arteries, and therefore does not lead to symptoms or signs of limb or organ ischemia. $M{\ddot{o}}nckeberg$ sclerosis most commonly occurs in aged and diabetic individuals and in patients on dialysis. $M{\ddot{o}}nckeberg$ arteriosclerosis is frequently observed in the visceral arteries, and it can occur in the head and neck region as well. This report describes a remarkable case of $M{\ddot{o}}nckeberg$ arteriosclerosis in the head and neck region as detected on dental imaging studies. To the best of our knowledge, this is the first case that has been reported in which this condition presented in the facial vasculature. The aim of this report was to define the radiographic characteristics of $M{\ddot{o}}nckeberg$ arteriosclerosis in an effort to assist health care providers in diagnosing and managing this condition.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.10
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• pp.494-501
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• 2001

In this study, the effects of vascular parameter changes and electrodes on VOP measurement based on IPG were simulated mathematically. For the evaluation of the effects of hemodynamic changes on VOP, a mathematical model, which consists of cardiovascular system model and venous occlusion model, was developed and the model solution representing the blood flow and pressure in measuring point was found by 2nd order Runge-Kutta method. And, with sensitivity coefficients obtained from finite element solution of electric field in measuring point, the effects of electrode system on measurement were evaluated. As increasing the resistance, the venous capacitance was not changed but the venous outflows were decreased and the decreased compliance reduced the venous capacitance. And, for several configurations of round electrodes and band electrodes, the sensitivity coefficients were computed using the electric field distribution along deep vein. In conclusion, the proposed mathematical cardiovascular model could be applied to the simulation study on the effects of hemodynamic parameters on DVT diagnosis with IPG. And, also the sensitivity coefficients could provide effective electrode configuration for exact measurement of VOP.

• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.221-230
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• 1999

A new technique for the preparation of porous polyurethane vascular prostheses was investigated. Synthetic vascular grafts with porous wall have been widely proposed, claiming that strength, suture retention, kink resistance, and other handling properties are improved over those with nonporous solid wall. Related to these facts, the control of pores and compliance match have been very important and interesting issues. Two kinds of polymer sheets were compared. One was the porous PU-sheet made at room temerature by the solvent/non-solvent exchange. And the other was the porous PU-sheet fabricated by thermal phase transition and solvent/non-solvent exchange in the thermal controlled bath. According to the result of the above experiments, polyurethane solution was injected into a mold designed for U-type graft. After freezing at low temperature, solvent was dissolved out with alcohol at < $0^{\circ}C$ and water at room temperature to form porous vessels. The average pore size and pore occupation were easily changed by changing polyurethane concentration and freezing rate. This technique can give a proper pore size for tissue ingrowth, and suitable compliances for matching with arteries and veins. In addition, the fabrication of more complicated shaped vessels such as the U-type vascular grafts is easily controlled by using a mold. This method might give a desired compliact graft for artificial implantaion with the commercially available medical polymers.

• Nutrition Research and Practice
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• v.3 no.4
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• pp.315-322
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• 2009

This study was designed to evaluate the effect of individualized diabetes nutrition education. The nutrition education program was open to all type 2 diabetes patients visiting the clinic center and finally 67 patients agreed to join the program. To compare with 67 education group subjects, 34 subjects were selected by medical record review. The education program consisted of one class session for 1-2 hours long in a small group of 4~5 patients. A meal planning using the food exchange system was provided according to the diet prescription and food habits of each subject. Measurements of clinical outcomes and dietary intakes were performed at baseline and 3 months after the education session. After 3 months, subjects in education group showed improvement in dietary behavior and food exchange knowledge. In education group, intakes of protein, calcium, phosphorus, vitamin $B_2$, and folate per 1,000 kcal/day were significantly increased and cholesterol intake was significantly decreased. They also showed significant reductions in body weight, body mass index (BMI), and fasting blood concentrations of glucose (FBS), HbA1c, total cholesterol, and triglyceride. However, no such improvements were observed in control group. To evaluate telephone consultation effect, after the nutrition education session, 34 subjects of the 67 education group received telephone follow-up consultation once a month for 3 months. The others (33 subjects) had no further contact after the nutrition education session. Subjects in the telephone follow-up group showed a decrease in BMI, FBS, and HbA1c. Moreover, the subjects who did not receive telephone follow-up also showed significant decreases in BMI and FBS. These results indicated that our individually planned education program for one session was effective in rectifying dietary behavior problems and improving food exchange knowledge, and quality of diet, leading to an improvement in the clinical outcomes. In conclusion, our individualized nutrition education was effective in adherence to diet recommendation and in improving glycemic control and lipid concentrations, while follow-up by telephone helped to encourage the adherence to diet prescription.

• Clinical and Experimental Pediatrics
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• v.56 no.12
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• pp.526-533
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• 2013

Purpose: Obesity is an important risk factor for hypertension in adolescents. We investigated the relationship of obesity-related indices (body mass index [BMI], waist-to-height ratio [WHR], and body fat percentage [%BF]) with blood pressure and the hemodynamic determinants of blood pressure in Korean adolescents. Methods: In 2008, 565 adolescents, aged 12-16 years, were examined. The %BF of the participants was measured by bioelectrical impedance analysis. Echocardiography and brachial artery pulse tracing were used to estimate the stroke volume (SV), cardiac output (CO), total vascular resistance (TVR), and total arterial compliance (TAC). Results: We noted that BMI, WHR, and %BF were positively correlated with systolic blood pressure (SBP) and diastolic blood pressure (DBP). The positive correlation between BMI and blood pressure (SBP and DBP) persisted after adjustment for WHR and %BF. However, after adjustment for BMI, the positive associations between blood pressure (SBP and DBP) and WHR as well as %BF, were not noted. With regard to the hemodynamic factors, BMI, but not WHR and %BF, was an independent positive factor correlated with SV and CO. TVR had an independent negative association with BMI; however, it was not associated with WHR or %BF. Moreover, we noted that BMI, WHR, and %BF did not affect TAC. Conclusion: In Korean adolescents, BMI had an independent positive correlation with SBP and DBP, possibly because of its effects on SV, CO, and TVR. WHR and %BF are believed to indirectly affect SBP and DBP through changes in BMI.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.10
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• pp.4609-4614
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• 2016

Purpose: To evaluate the therapeutic effects of copper reduction on angiogenesis-related factors in patients with glioblastoma multiforme treated by gamma knife radiosurgery. Materials and Methods: In the present block randomized, placebo-controlled trial, fifty eligible patients with a diagnosis of glioblastoma multiforme who were candidates for gamma knife radiosurgery were randomly assigned into two groups to receive daily either 1gr penicillamine and a low copper diet or placebo for three months. The intervention started on the same day as gamma knife radiosurgery. Serum interleukin-6 (IL-6), tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$), vascular endothelial growth factor (VEGF) and copper levels were measured at baseline and after the intervention. The serum copper level was used as the final index of compliance with the diet. In order to control probable side effects of intervention, laboratory tests were conducted at the beginning, middle and end of the study. Results: The patients had a mean age and Karnofsky Performance Scale of 43.7 years and 75 respectively. Mean serum copper levels were significantly reduced in intervention group. Mean survival time was 18.5 months in intervention group vs. 14.9 in placebo group. VEGF and IL-6 levels in the intervention group were also significantly reduced compared to the placebo group and $TNF-{\alpha}$ increased less. Conclusions: It seems that reducing the level of copper in the diet and dosing with penicillamine leads to decline of angiogenesis-related factors such as VEGF, IL-6 and $TNF-{\alpha}$. Approaches targeting angiogenesis may improve survival and can be used as a future therapeutic strategy.

• Journal of Korean Biological Nursing Science
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• v.16 no.3
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• pp.251-257
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• 2014

Purpose: Little is known about appropriate interval periods between the heparin flushing of implanted ports after completion of chemotherapy. The purpose of this study was to describe the current status of interval of heparin flushing for maintenance of an implanted port in solid tumor patients. Methods: We performed a retrospective review of all patients who had undergone implanted port removal in 2012 at the Seoul St. Mary's Hospital. The subjects were 90 patients who, after completion of chemotherapy, retained their ports for extended periods of time. Results: The mean number of flushes of heparin was 4. Compliance with visits for implanted port maintenance varied with the individual, and the mean accession times were in the range between 13 days and 243 days. The overall mean time between flushes was 66 days. One patient showed resistance during flushing. Conclusion: Our results demonstrate that extending the flushing interval to a maximum of 8 weeks remains medically safe. Less frequent heparin flushing of an implanted port decreases medical expenditure and the workload of medical professionals; it also improves the patient's satisfaction.

• YAKHAK HOEJI
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• v.37 no.5
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• pp.442-452
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• 1993

Previous experimental and clinical investigations suggest a possible role of new nootropic drug, oxiracetam, in improving cognitive performances in patients affected by organic brain syndrome. In this study, the cognitive and behavioral effects of oxiracetam treatment in patients with clinical symptoms of organic brain syndrome were evaluated. Sixty-six patients were enrolled and assigned to either oxiracetam or placebo, according to a randomized, double-blind design between two patient-groups. Either oxiracetam or placebo was orally given bid for 8 weeks ; daily dose of oxiracetam was 1600mg. All the patients, enrolled in this study, were diagnosed as having mild to moderate cognitive dysfunction as defined by a baseline Mini Mental State ExaminationKorean version (MMSE-K) score between 14 and 25. The patients under-went, at baseline, 4 weeks and 8 weeks after, routine laboratory study (CBC, SMA12, U/A, EKG) and the following neuropsychological tests ; MMSE-K, modified Korean Wechsler Intelligence Scale(MKWIS), Nurses' Observation Scale for Geriatric patients(NOSGER). Fifteen patients of whom were dropped out or excluded from the analysis because of poor compliance or violation of the protocol. Fiftyone patients (aged 54~78 years, male 25, female 26) were analyzed (vascular dementia, 30 ; senile dementia of Alzheimer type, 9 ; mixed type, 5 ; other cause, 7). Statistical analysis of the data demonstrated that the two groups were comparable at baseline. At the end of each study period the oxiracetam group scored significantly better on the majority of the tests evaluating cognitive function, psychometricity and the improvement rating scale of subjective symptoms than placebo group, in which worsening trends or no changes were seen on the whole. No side effects were noted during oxiracetam treatment. The present study, showing positive clinical findings after oxiracetam therapy, confirmed that this drug can be useful pharmacological treatment in organic brain syndrome.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.691-697
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• 2013

Recently, u-healthcare device is developed and commercialized for healthcare management and emergency medical. The kinds of the measurable biomedical signals on the device are electrocardiogram, skin temperature, pulse oxygen, heart rate, respiration, etc. Specially, the photoplethysmograph(PPG) signal of these signals is the important signal in measuring oxygen, heart rate and peripheral vascular compliance. The accuracy of PPG signal reduce from influence of the motion artifacts that generated from the movements of user or patient. Therefore, this study suggests a new method to remove the motion artifact that is using optical power modulation and ICA(Independent Component Analysis). For analyzing the proposed method, we used variety of noises made by artificially. In the results of experiments, the proposed method showed good performances than an adaptive filter.