-
[show abstract]
[hide abstract]
ABSTRACT: To quantify the reduction in workload during intra-aortic balloon pump (IABP) therapy, indirect parameters are used, such as the mean arterial pressure during diastole, product of heart rate and peak systolic pressure, and pressure-volume area. Therefore, we investigated the cardiac energy consumption during IABP therapy using a cardiac electromechanics model. We incorporated an IABP function into a previously developed electromechanical model of the ventricle with a lumped model of the circulatory system and investigated the cardiac energy consumption at different IABP inflation volumes. When the IABP was used at inflation level 5, the cardiac output and stroke volume increased 11%, the ejection fraction increased 21%, the stroke work decreased 1%, the mean arterial pressure increased 10%, and the ATP consumption decreased 12%. These results show that although the ATP consumption is decreased significantly, stroke work is decreased only slightly, which indicates that the IABP helps the failed ventricle to pump blood efficiently.
Journal of Korean medical science 01/2013; 28(1):93-9. · 0.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Key points L-type Ca(2+) channels are inactivated by an increase in intracellular [Ca(2+)], known as Ca(2+)-dependent inactivation (CDI), and are inhibited by Ca(2+) released from the sarcoplasmic reticulum (SR), known as release-dependent inhibition (RDI). RDI was greatly enhanced by the removal of Na(+)-Ca(2+) exchange (Incx), and attenuated by blocking Ca(2+) release from the sarcoplasmic reticulum (SR), and abolished by Ca(2+) chelator. We analysed the role of ICaL, SR and Incx and found Incx prevented CDI by controlling [Ca(2+)] in the junctional subsarcolemmal space ([Ca(2+)](JSS)). With previously developed model and the addition of Ca(2+) binding kinetics of L-type Ca(2+) channels (ICaLs), we successfully reproduced CDI and RDI. From this simulation, we found Incx actively participated in controlling CDI by the regulation of [Ca(2+)](JSS) and by controlling SR Ca(2+) refilling.
The Journal of Physiology 06/2012; 590(Pt 18):4447-63. · 4.72 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: PurposeThis paper will introduce basic information on mitochondrial medicine and the direction of research. This paper will first
introduce basic information on mitochondrial medicine and the direction of research. Then, it will delineate recent research
on biomedical engineering methods and applications of mitochondrial medicine and discuss prospects of this research.
MethodsRecent research on mitochondrial medicine is based mostly on molecular biology. However, because energy production by mitochondria
is linked closely to the macroscopic energy balance of the human body, the need for integrated research, based on systemic
methods, is increasing.
ResultsMitochondrial medicine is expanding as a multidisciplinary field, and biomedical engineering applications are becoming more
important. Using advances in optics or sensor technology, more engineering approaches should be effective in mitochondrial
medicine.
ConclusionsConsidering its broad scope and outcome as a diagnostic method, mitochondrial medicine will be a future paradigm of biomedical
science, although it has numerous limitations at present.
KeywordsMitochondrial medicine–Macroscopic energy balance–Biomedical engineering methods
04/2012; 1(1):21-26.
-
[show abstract]
[hide abstract]
ABSTRACT: A shunt from the left ventricle to the left anterior descending artery is being developed for coronary artery occlusive disease,
in which the shunt or conduit connects the the left ventricle (LV) with the diseased artery directly at a point distal to
the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed
and used to explore various design conditions. Computational fluid dynamic analysis for the shunt hemodynamics was also done
using a commercial finite element package. Simulation results indicate that in complete left anterior descending artery (LAD)
occlusion, flow can be returned to approximately 65% of normal, if the conduit resistance is equal for forward and reverse
flow. The net coronary flow can increase to 80% when the backflow resistance is infinite. The increases in flow rate produced
by asymmetric flow resistance are enhanced considerably for a partial LAD obstruction, since the primary effect of resistance
asymmetry is to prevent leakage back into the ventricle during diastole. Increased arterial compliance has little effect on
net flow with a symmetric shunt, but considerably augments it when the resistance is asymmetric. The computational results
suggest that an LV-LAD conduit will be beneficial when the resistance due to artery stenosis exceeds 27 PRU. if the resistance
is symmetric. Fluid dynamic simulations for the shunt flow show that a recirculating region generated near the junction of
the coronary artery with the bypass shunt. The secondary flow is induced at the cutting plane perpendicular to the axis direction
and it is in the attenuated of coronary artery.
Journal of Mechanical Science and Technology 04/2012; 19(5):1158-1168. · 0.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We developed a computational model to investigate the hemodynamic effects of a pulsatile left ventricular assist device (LVAD)
on the cardiovascular system. The model consisted of 16 compartments for the cardiovascular system, including coronary circulation
and LVAD, and autonomic nervous system control. A failed heart was modeled by decreasing the end-systolic elastance of the
ventricle and blocking the mechanism controlling heart contractility. We assessed the physiological effect of the LVAD on
the cardiovascular system for three types of LVAD flow: co-pulsation, counter-pulsation, and continuous flow modes. The results
indicated that the pulsatile LVAD with counter-pulsation mode gave the most physiological coronary blood perfusion. In addition,
the counter-pulsation mode resulted in a lower peak pressure of the left ventricle than the other modes, aiding cardiac recovery
by reducing the ventricular afterload. In conclusion, these results indicate that, from the perspective of cardiovascular
physiology, a pulsatile LVAD with counter-pulsation operation is a plausible alternative to the existing LVAD with continuous
flow mode.
The Journal of Physiological Sciences 04/2012; 59(4):307-316. · 1.61 Impact Factor
-
Computational and Mathematical Methods in Medicine 01/2012; 2012:260396. · 0.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Left ventricular assist device (LVAD) support under cannulation connected from the left atrium to the aorta (LA-AA) is used as a bridge to recovery in heart failure patients because it is non-invasive to ventricular muscle. However, it has serious problems, such as valve stenosis and blood thrombosis due to the low ejection fraction of the ventricle. We theoretically estimated the effect of the in-series cannulation, connected from ascending aorta to descending aorta (AA-DA), on ventricular unloading as an alternative to the LA-AA method. We developed a theoretical model of a LVAD-implanted cardiovascular system that included coronary circulation. Using this model, we compared hemodynamic responses according to various cannulation methods such as LA-AA, AA-DA, and a cannulation connected from the left ventricle to ascending aorta (LV-AA), under continuous and pulsatile LVAD supports. The AA-DA method provided 14% and 18% less left ventricular peak pressure than the LA-AA method under continuous and pulsatile LVAD conditions, respectively. The LA-AA method demonstrated higher coronary flow than AA-DA method. Therefore, the LA-AA method is more advantageous in increasing ventricular unloading whereas the AA-DA method is a better choice to increase coronary perfusion.
Journal of Korean medical science 12/2011; 26(12):1591-8. · 0.84 Impact Factor
-
Dae-Sung Lee,
Won Sun Park,
Soo-Jin Heo,
Seon-Heui Cha,
Daekyung Kim,
You-Jin Jeon,
Sae-Gwang Park,
Su-Kil Seo,
Jung Sik Choi,
Sung-Jae Park, Eun Bo Shim,
Il-Whan Choi,
Won-Kyo Jung
[show abstract]
[hide abstract]
ABSTRACT: Marine algae have been utilized in food as well as medicine products for a variety of purposes. The purpose of this study was to determine whether an ethanol extract of Polyopes affinis (P.affinis) can inhibit the pathogenesis of T helper 2 (Th2)-mediated allergen-induced airway inflammation in a murine model of asthma. Mice that were sensitized and challenged with ovalbumin (OVA) evidenced typical asthmatic reactions such as the following: an increase in the number of eosinophils in the bronchoalveolar lavage (BAL) fluid; a marked influx of inflammatory cells into the lung around blood vessels and airways as well as the narrowing of the airway luminal; the development of airway hyperresponsiveness (AHR); the presence of pulmonary Th2 cytokines; and the presence of allergenspecific immunoglobulin E (IgE) in the serum. The successive intraperitoneal administration of P. affinis ethanolic extracts before the last airway OVA-challenge resulted in a significant inhibition of all asthmatic reactions. These data suggest that P. affinis ethanolic extracts possess therapeutic potential for the treatment of pulmonary allergic disorders such as allergic asthma.
Journal of Biosciences 12/2011; 36(5):869-77. · 1.65 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Left ventricular-assist devices (LVADs) are used to supply blood to the body of patients with heart failure. Pressure unloading is greater for counter-pulsating LVADs than for continuous LVADs. However, several clinical trials have demonstrated that myocardial recovery is similar for both types of LVAD. This study examined the contractile energy consumption of the myocardium with continuous and counter-pulsating LVAD support to ascertain the effect of the different LVADs on myocardial recovery. We used a three-dimensional electromechanical model of canine ventricles, with models of the circulatory system and an LVAD. We compared the left ventricular peak pressure (LVPP) and contractile ATP consumption between pulsatile and continuous LVADs. With the continuous and counter-pulsating LVAD, the LVPP decreased to 46 and 10%, respectively, and contractile ATP consumption decreased to 60 and 50%. The small difference between the contractile ATP consumption of these two types of LVAD may explain the comparable effects of the two types on myocardial recovery.
The Journal of Physiological Sciences 11/2011; 62(1):11-9. · 1.61 Impact Factor
-
Youn Kyoung Son,
Seong Woo Choi,
Won-Kyo Jung,
Su-Hyun Jo,
In Duk Jung,
Yeong-Min Park,
Il-Whan Choi,
Jeong-Im Sin, Eun Bo Shim,
Nari Kim,
Jin Han,
Won Sun Park
[show abstract]
[hide abstract]
ABSTRACT: We investigated the effects of BMS-204352 (BMS), a big-conductance calcium-activated potassium (BK(Ca)) channel activator, on L-type Ca(2+) channels.
Electrophysiological recordings were performed in isolated rat ventricular myocytes. Whole-cell configuration was used.
BMS caused inhibition of the Ca(2+) current in a dose-dependent manner, with K(d) of 6.00 ± 0.67 μM and a Hill coefficient of 1.33 ± 0.18. BMS did not affect the steady-state activation of L-type Ca(2+) channels. However, for those in steady-state inactivation, BMS shifted the half-maximal potential (V(1/2)) by -11 mV, but the slope value (k) was not altered. Iberiotoxin, inhibitor of membrane BK(Ca) channels and paxilline, inhibitor of mitochondrial BK(Ca) channel did not affect the inhibitory effect of BMS on L-type Ca(2+) channels. Pretreatment with inhibitors of protein kinase A (PKA), protein kinase C (PKC), and protein kinase G (PKG) did not significantly alter the inhibitory effect of BMS on L-type Ca(2+) current. The presence of a selective β-adrenergic receptor agonist, isoproterenol did not affect the inhibitory effect of BMS on L-type Ca(2+) current. Based on these results, we concluded that the inhibition of L-type Ca(2+) channels by BMS is independent of the inhibition of BK(Ca) channels or intracellular signaling pathways.
It is important to take BMS-204352 (BMS) effects on L-type Ca(2+) channels into consideration when using BMS as a BK(Ca) channel activator or therapeutic target in ventricular myocytes.
Life sciences 08/2011; 89(9-10):331-6. · 2.56 Impact Factor
-
Won Sun Park,
Won-Kyo Jung,
Seong Kook Park,
Kyung Wook Heo,
Mi-Seon Kang,
Yung Hyun Choi,
Gi-Young Kim,
Sae-Gwang Park,
Su-Kil Seo,
Sung Su Yea,
Kwang-Hyeon Liu, Eun Bo Shim,
Dae-Joong Kim,
Minyoung Her,
Il-Whan Choi
[show abstract]
[hide abstract]
ABSTRACT: Galectin-9 exhibited potent and selective eosinophil chemoattractant activity and attracted eosinophils in vitro and in vivo. Nasal polyposis is a chronic inflammatory disease of the upper airway characterized by the marked presence of inflammatory cells, particularly eosinophils. Thus, galectin-9 may be implicated in the pathogenesis of nasal polyposis. The study was designed to investigate whether interferon-gamma (IFN-γ) can induce the augmentation of galectin-9 expression and induce the expression of galectin-9 in nasal polyps. We examined the correlation between galectin-9 expression and eosinophil infiltration in nasal polyps. In addition, we identified the signaling pathways involved in the elevation of galectin-9 expression in response to IFN-γ. Our data demonstrate that the involvement of mitogen-activated protein kinases (MAPKs), phosphatidylinositol 3 phosphate kinase (PI3K), and Janus kinase/signal transducer and activator of transcription (JAK/STAT) may play important roles in the selective recruitment of eosinophils in nasal polyp tissues through the production of galectin-9. These findings suggest that galectin-9 expression is associated with eosinophil infiltration in polyps of patients with nasal polyposis.
Biochemical and Biophysical Research Communications 06/2011; 411(2):259-64. · 2.48 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this letter, we discuss a sensor-integrated system model for metabolic syndrome prediction with workflow system. This model measures not only a cell temperature variation using invasive method but also controlling simulation for metabolic syndrome prediction. To identify the system realization, we discuss the schemes for predicting metabolic syndrome from measurement of mitochondrial activity by using high precision sensors and integrated simulation model of human energetic under high performance workflow computing environment. To predict metabolic syndrome, we built a sensor-integrated chamber that had network interface to deliver analysis results of human cells, annotation data from public hospital, and metabolic data. Using the proposed system, we showed the possibility to evaluate the functionality of human mitochondria and analyze energy metabolism.
IEEE transactions on bio-medical engineering 03/2011; 58(3):809-13. · 2.15 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: For blood purification systems using a semipermeable membrane, the convective mass transfer by ultrafiltration plays an important role in toxin removal. The increase in the ultrafiltration rate can improve the toxin removal efficiency of the device, ultimately reducing treatment time and cost. In this study, we assessed the effects of pulsatile flow on the efficiency of the convective toxin removal in blood purification systems using theoretical methods.
We devised a new mathematical lumped model to assess the toxin removal efficiency of blood purification systems in patients, integrating the mass transfer model for a human body with a dialyser. The human body model consists of a three-compartment model of body fluid dynamics and a two-compartment model of body solute kinetics. We simulated three types of blood purification therapy with the model, hemofiltration, hemodiafiltration, and high-flux dialysis, and compared the simulation results in terms of toxin (urea and beta-2 microglobulin) clearance and the treatment dose delivered under conditions of pulsatile and non-pulsatile pumping. In vivo experiments were also performed to verify the model results.
Simulation results revealed that pulsatile flow improved the convective clearance of the dialyser and delivered treatment dose for all three types of therapy. Compared with the non-pulsatile pumping method, the increases in the clearance of urea and beta-2 microglobulin with pulsatile pumping were highest with hemofiltration treatment (122.7% and 122.7%, respectively), followed by hemodiafiltration (3.6% and 8.3%, respectively), and high-flux dialysis (1.9% and 4.7%, respectively). EKRc and std Kt/V averaged 28% and 23% higher, respectively, in the pulsatile group than in the non-pulsatile group with hemofiltration treatment.
The pulsatile effect was highly advantageous for all of the toxins in the hemofiltration treatment and for beta2-microglobulin in the hemodiafiltration and high-flux dialysis treatments.
BioMedical Engineering OnLine 01/2010; 9:31. · 1.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper proposes a policy adjuster-driven Grid workflow management system, which supports collaborative heart disease diagnosis
applications. To select policies according to service level agreement of users and dynamic resource status, we devised a policy
adjuster to negotiate workflow management polices and resource management policies using policy decision scheme.
11/2009: pages 93-102;
-
[show abstract]
[hide abstract]
ABSTRACT: The centerpiece of the pathophysiologic mechanism of metabolic syndrome is insulin resistance. Recently, it is becoming evident that mitochondrial dysfunction is closely related to insulin resistance and metabolic syndrome. The underlying mechanism of mitochondrial dysfunction is very complex, which includes genetic factors from both nuclear and mitochondrial genome and numerous environmental factors. Several mitochondrial DNA polymorphisms are associated with the components of metabolic syndrome. Numerous chemicals and drugs may cause mitochondrial dysfunction and insulin resistance. Notably, it was recently reported that serum levels of several mitochondrial toxins, such as persistent organic pollutants are associated with metabolic syndrome, which necessitates further investigation to reveal its precise mechanism. Given that the health impact of metabolic syndrome is tremendous, it is necessary to develop therapeutic modalities to correct mitochondrial dysfunction or at least to halt its aggravation. In this regard, exercise can improve both mitochondrial function and insulin sensitivity, and some pharmaceutical agents were reported to improve mitochondrial function. However, further studies are warranted to find more effective therapeutic strategies to treat mitochondrial dysfunction. By doing so, we can also shed light on the path of research for other diseases related to mitochondrial dysfunction.
Biochimica et Biophysica Acta 11/2009; 1800(3):282-9. · 4.66 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We previously developed the cold dialysate regeneration system (CDRS) for use in daily home hemodialysis (HD). This study evaluates the long-term efficacy of the CDRS using a mathematical method.
HD with the CDRS was simulated using a method that integrates the mass-transfer model and the dialyzer solute kinetics model with a newly proposed model of CDRS function.
We mathematically assessed the long-term efficacy of HD with the CDRS. The weekly treatment time required for HD with the CDRS was reduced significantly using the daily dialysis method; it required only an 11% longer treatment time to obtain the corrected equivalent renal clearance and a 14% shorter time for the standard Kt/V, compared with thrice weekly treatment with conventional HD.
By developing a mathematical model to test the long-term efficacy of the new CDRS, we showed that HD with the CDRS is an efficient means of daily home hemodialysis therapy.
Blood Purification 10/2009; 29(1):27-34. · 2.10 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We evaluated the quantitative contribution of pulsatile flow to ultrafiltration (UF) in terms of fluid power, membrane stretch, and reduction of membrane layering. An in vitro comparison of the UF rate using pulsatile and roller pumps was performed with distilled water and bovine whole blood. The mean transmembrane pressure (TMPm) and UF rate were higher with the pulsatile pump for the same mean flow rate: 6.6 mm Hg and 21.1 mL/min higher on average for distilled water and 34.2 mm Hg and 31.4 mL/min higher on average for blood. The average UF rate was 8.4 mL/min higher with the pulsatile pump for the same TMPm with bovine blood. However, the relationship between the UF rate and the TMPm was independent of the flow configuration for distilled water. We showed that the higher UF rate in the pulsatile pump is mainly due to greater fluid power and reduction of membrane layering, while the membrane stretch was not an important factor.
Artificial Organs 02/2009; 33(1):69-73. · 2.00 Impact Factor
-
The 10th International Symposium on Pervasive Systems, Algorithms, and Networks, ISPAN 2009, Kaohsiung, Taiwan, December 14-16, 2009; 01/2009
-
[show abstract]
[hide abstract]
ABSTRACT: Sasang Constitutional Medicine (SCM) is a traditional Korean form of medicine widely used in the clinical diagnosis and treatment of disease. This paper reviews the main aspects of SCM and "physiome" with emphasis on integrative and holistic characteristics. Methodological and physiological aspects of SCM are summarized with reference to existing studies. The main characteristics of SCM, such as the four physical constitutions and diagnostic methods, are introduced. Moreover, physiome and systems medicine are introduced as plausible candidates for integrative medicine and are compared to reductionism-based molecular biology. We also discuss the conceptual similarity of SCM with predictive, preventive, personalized, and participatory (P4) medicine. It is emphasized that the integrative and creative combination of SCM and physiome will unlock a new era of holistic medicine.
The Journal of Physiological Sciences 11/2008; 58(7):433-40. · 1.61 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We developed a numerical model that predicts cardiovascular system response to hemodialysis, focusing on the effect of sodium profile during treatment.
The model consists of a 2-compartment solute kinetics model, 3-compartment body fluid model, and 12-lumped-parameter representation of the cardiovascular circulation model connected to set-point models of the arterial baroreflexes. The solute kinetics model includes the dynamics of solutes in the intracellular and extracellular pools and a fluid balance model for the intracellular, interstitial, and plasma volumes. Perturbation due to hemodialysis treatment induces a pressure change in the blood vessels and the arterial baroreceptors then trigger control mechanisms (autoregulation system). These in turn alter heart rate, systemic arterial resistance, and cardiac contractility. The model parameters are based largely on the reported values.
We present the results obtained by numerical simulations of cardiovascular response during hemodialysis with 3 different dialysate sodium concentration profiles. In each case, dialysate sodium concentration profile was first calculated using an inverse algorithm according to plasma sodium concentration profiles, and then the percentage changes in each compartment pressure, heart rate, and systolic ventricular compliance and systemic arterial resistance during hemodialysis were determined. A plasma concentration with an upward convex curve profile produced a cardiovascular response more stable than linear or downward convex curves.
By conducting numerical tests of dialysis/cardiovascular models for various treatment profiles and creating a database from the results, it should be possible to estimate an optimal sodium profile for each patient.
Yonsei Medical Journal 09/2008; 49(4):581-91. · 1.14 Impact Factor
