Chul-Un Hong

Taurine increases cell proliferation and generates an increase in [Mg2+]i accompanied by ERK 1/2 activation in human osteoblast cells

Taurine has been reported to influence bone metabolism, and its specific transport system, the taurine transporter, is expressed in osteoblasts. The mean [Mg2+]i was 0.51 ± 0.01 mM in normal culture media. Taurine caused an increase in [Mg2+]i by 0.72 ± 0.04 mM in human osteoblast (HOB) cells. This increment in [Mg2+]i was inhibited significantly by PD98059, nifedipine, lidocaine, and imipramine. Taurine was also shown to stimulate the activation of ERK 1/2. This taurine‐stimulated ERK 1/2 activation was inhibited by PD98059. In the present study, taurine was shown to increase cell proliferation and generate an increase in [Mg2+]i accompanied by ERK 1/2 activation in HOB cells.

Taurine Prevents Hypertension and Increases Exercise Capacity in Rats With Fructose-Induced Hypertension

BACKGROUND Fructose-induced hypertension was used to test the hypothesis that taurine supplementation and/or exercise can prevent hypertension and increase exercise capacity. METHODS Five groups of 15 Sprague-Dawley rats were allocated and designated as control, high fructose-fed (fructose), high fructose-fed plus exercise (FE), high fructose-fed plus 2% taurine supplement (FT) and high fructose-fed plus 2% taurine supplement and exercise (FET) groups. Noninvasive systolic blood pressure (SBP) was recorded weekly and invasive arterial blood pressure (ABP) was recorded at the end of the 4-week trial. Three consecutive swimming tests were performed in the selected rats from each group and the plasma biomarkers were measured in the remaining rats. RESULTS Noninvasive SBP differed significantly (P < 0.001) from week 3, both noninvasive and invasive ABP increased significantly (P < 0.001), and exercise capacity significantly decreased (P < 0.001) in the fructose group compared with the control group. The individual effects of swimming and taurine supplementation were incapable of preventing the development of hypertension and SBP significantly (P < 0.001) increased in the FE and FT groups; exercise capacity in those groups remained similar to control. The combined effects of exercise and taurine alleviated hypertension and significantly increased exercise capacity in the FET group. Insulin resistance increased significantly and plasma nitric oxide (NO) decreased significantly in the F, FE, and FT groups. Both parameters remained similar to control values in the FET group with an increasing antioxidant activity. CONCLUSION Taurine supplementation in combination with exercise prevents hypertension and increases exercise capacity by possibly antioxidation and maintaining NO concentrations.

The antioxidant, taurine reduced lipopolysaccharide (LPS)-induced generation of ROS, and activation of MAPKs and Bax in cultured pneumocytes.

Lipopolysaccharide (LPS) can cause damage to the epithelia of the respiratory tract. However, taurine can protect the lung tissue from such oxidant-induced inflammation. This study examined the effects of a LPS treatment on the intracellular calcium levels ([Ca(2+)]i) as well as the specific mechanisms of LPS-induced cell death in pneumocytes. In addition, the effects of taurine on the LPS-induced increase in the accumulation of reactive oxygen species (ROS) in pneumocytes were investigated. The [Ca(2+)]i in cultured pneumocytes was determined using microfluorescence techniques. The level of activation of the mitogen-activated protein kinases (MAPKs) and Bax protein were measured by Western blotting. LPS at 10 and 100 ng/ml induced cell death and decreased the viability of MRC-5 cells. Moreover, the intracellular Ca(2+) and ROS levels were increased by LPS. The LPS treatment led to the phosphorylation of ERK1/2, JNK and the activation of Bax. A pretreatment with 20 mM taurine reduced the LPS-induced production of ROS and MARK activity. These results show that a LPS treatment induces cell death in MRC-5 cells by increasing the intracellular ROS and Ca(2+) levels. The increase in the intracellular level of ROS promotes MAPKs activation and Bax translocation. Overall, LPS induces lung cell death by activating MAPKs. Furthermore, taurine decreased the LPS-induced generation of ROS and activation of MAPK and Bax.

Nitrite‐Induced Methemoglobinaemia Affects Blood Ionized and Total Magnesium Level by Hydrolysis of Plasma Adenosine Triphosphate in Rat

The objective of this study was to evaluate the effects of sodium nitrite (NaNO(2))-induced methemoglobinaemia on plasma ATP (adenosine triphosphate) and corresponding changes of blood-ionized magnesium (iMg(2+)) as well as total magnesium (tMg(2+)) in a time-dependent manner. This study was performed on male Sprague-Dawley rats to which NaNO(2) was injected (10 mg/kg i.p.) to induce methemoglobinaemia. Methemoglobin (MetHb) in blood was measured before (0 min.) and after 10, 30, 60 and 120 min. of NaNO(2) injection. At respective time points, the tMg(2+), blood ions and gases were measured by atomic absorption spectrometry and ion selective electrode, respectively. Haematological parameters were checked by automatic blood cell count, and blood films were observed under light microscope. Plasma ATP was measured by bioluminescence assay using a luminometer, and plasma proteins were measured by an automatic analyser. Blood cell count (RBC, WBC and platelet), haematocrit, and haemoglobin were found to be decreased with the advancement of MetHb concentration. With the gradual increase of MetHb concentration, the plasma ATP decreased and blood iMg(2+) and plasma tMg(2+) increased significantly as time passed by in comparison with the pre-drug values. A significant decrease of the ratio of ionized calcium to iMg(2+), Na(+) and increase of K(+) was observed. In conclusion, NaNO(2)-induced methemoglobinaemia is a cause of hydrolysis of plasma ATP which is responsible for the increase of blood iMg(2+) and plasma tMg(2+) in rats.

Characteristics of the Muscle Activities of the Elderly wearing the Lower limb Orthosis during Gait on the Treadmill

We have developed a lower limb orthosis with a pneumatic rubber actuator, which is intended for the assistance and the enhancement of lower limb muscular activities of the elderly. For this purpose, we investigated the characteristics of the muscular activities with and without the orthosis in gait motion on treadmill. To find out the characteristics of the muscle activities, we analyzed the gait motion of the subject and flexing and extending motion of the knees and measured muscular power in the lower limb. The subjects wearing the lower limb orthosis were instructed to perform gait on the treadmill and flexing and extending motion of the knees in sitting position for monitoring of electromyogram and muscular activities. We used the C8051F Target Board (SILICON LABORATORIES, Inc., USA) for the orthosis control. The air pressure of the pneumatic actuator was varied from one kgf/cm2 to four kgf/cm2 to find the most suitable air pressure. Through this study, we expect to find the effect of the lower limb orthosis in the gait motion and muscular activities along with the most suitable air pressure in the pneumatic actuator of the orthosis for the enhancement of muscular power for the elderly

Enhancement of oxygen transfer in hollow fiber membrane by the vibration method

The purpose of this study was to assess and quantify the beneficial effects of gas exchange according to the various frequencies of the sinusoidal wave that are excited by a PZT actuator, on patients suffering from acute respiratory distress syndrome (ARDS). In this study, an experimental method for the flow hydrodynamics was developed through a bundle of sinusoidally vibrated hollow fibers to observe how well vibrations might enhance the performance of the VIVLAD. We measured the effect of the various excitation frequencies of the PZT actuator on the gas transfer rates and hemolysis from the maximum gas transfer rate. As a result, the maximum oxygen transfer rate was reached at the maximum amplitude and through the transfer of vibrations to the hollow fiber membranes. The device was maximum excited by a frequency band of 7 Hz at various water flow rates, as this frequency was the 2nd mode resonance frequency of the flexible beam. 675 hollow fiber membranes were also bundled, within the blood flow, into the device.

Vibration Characteristics of Piezoelectric Lead Zirconate Titanate by Fluid Flow in Intravascular Oxygenator

In this paper, we describe the enhancement in oxygen transfer rate in hollow-fiber-membrane (HFM) modules using a plumbum piezoelectric lead zirconate titanate (PZT) actuator and a piezoelectric poly vinylidene fluoride (PVDF) sensor. We developed a vibrating intravascular lung assist device (VIVLAD) for patients having chronic respiratory problems and performed experiments on hydrodynamic flow through a bundle of sinusoidal vibrating hollow fibers. These modules were used to provide some insight into how wall vibrations might enhance the performance of an intravascular lung assist device. The experimental design and procedure are then applied to the fabrication of a device used to assess the effectiveness of membrane vibrations. The test section was a cylindrical duct with an inner diameter of 30 mm. The flow rate was controlled by a pump and monitored by a built-in flowmeter. The vibration apparatus was composed of a piezovibrator, a function generator, and a power amplifier. The direction of vibration was radial to the fluid flow. Gas flow rates of up to 6 L/min through 120-cm-long hollow fibers were achieved by exciting the piezovibrator. The time and frequency responses of PVDF sensors were investigated through various frequencies in VIVLAD. In these devices, the flow of blood and the source of oxygen were separated by a semipermeable membrane that allows oxygen and carbon dioxide to diffuse into and out of the fluid, respectively. Results of the experiments have shown that a vibrating intravascular lung assist device performs effectively.

Basic Study to Develop Biosensors Using Surface Acoustic Waves

In this paper, we present a study of the bonding between piezoelectric substrates and semiconductor materials. We have studied [O. S. Wolfbesis: Fiber Optic Chemical Sensors and Biosensors, 1st ed. (CRC Press, Boca Raton, 1991) p. 21.] the surface state (hydrophilic) of GaAs, LiNbO3 and quartz substrates after different treatments methods [R. Hughes, A. Ricco, M. Butler and S. Martin: Science 254 (1991) 74.], the effects of migration of water molecules out of bonding surfaces induced by microwave and laser radiation. When Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) is used as a piezoelectric material, we have evaluated if PMN-PT can be made practically available for a new surface acoustic wave (SAW) biosensor detecting protein. The experimental results clarified that improvements in the bonding process are effective in obtaining a stronger bonding interface between the piezoelectric substrate and semiconductor materials. The frequency filtering of the central frequency of the PMN-PT substrate is also superior to that of the LiTaO3 substrate, but the result was not completely satisfactory. However, the electromechanical coupling coefficient of the PMN-PT substrate is excellent, therefore it will be used as a SAW sensor, in the near future, provided that new interdigital transducer (IDT) design will also be available to increase the frequency of filtering.

Dynamic Analysis and Structural Optimization of a Fiber Optic Sensor Using Neural Networks

The objective of this work is to apply artificial neural networks for solving inverse problems in the structural optimization of a fiber optic pressure sensor. For the sensor under investigation to achieve a desired accuracy, the change in the distance between the tips of the two fibers due to the applied pressure should not interfere with the phase change due to the change in the density of the air between the two fibers. Therefore, accurate dynamic analysis and structural optimization of the sensor is essential to ensure the accuracy of the measurements provided by the sensor. To this end, a normal mode analysis and a transient response analysis of the sensor were performed by combining commercial finite element analysis package, MSC/NASTRAN, and MATLAB. Furthermore, a parametric study on the design of the sensor was performed to minimize the size of the sensor while fulfilling a number of constraints. In performing the parametric study, the need for a relationship between the design parameters and the response of the sensor was fulfilled by using a neural network. The whole process of the dynamic analysis using commercial finite element analysis package and the parameter optimization of the sensor were automated within the MATLAB environment.

Experimental Studies on the Training of Postural Control Using an Unstable Platform

We performed experimental studies on the training of postural control using a training system which consists of an unstable platform, a computer, a computer interface, a monitoring device, and training programs. Using this system with the training programs that we have developed, we performed a variety of experiments of training the abilities of postural control of subjects. To evaluate the effects of the training, the parameters on how long a subject can maintain a focus on a target, the mean absolute deviation of the trace, and the fatigue of the muscles in lower limbs were measured. The experimental results showed that the training system can improve the ability of postural control of the subject. Therefore, the training system could be applied to clinical rehabilitation training for posture control as a new balance training system