The Scaffolding Protein, Grb2-associated Binder-1, in Skeletal Muscles and Terminal Schwann Cells Regulates Postnatal Neuromuscular Synapse Maturation

The vertebrate neuromuscular junction (NMJ) is considered as a “tripartite synapse” consisting of a motor axon terminal, a muscle endplate, and terminal Schwann cells that envelope the motor axon terminal. The neuregulin 1 (NRG1)-ErbB2 signaling pathway plays an important role in the development of the NMJ. We previously showed that Grb2-associated binder 1 (Gab1), a scaffolding mediator of receptor tyrosine kinase signaling, is required for NRG1-induced peripheral nerve myelination. Here, we determined the role of Gab1 in the development of the NMJ using muscle-specific conditional Gab1 knockout mice. The mutant mice showed delayed postnatal maturation of the NMJ. Furthermore, the selective loss of the gab1 gene in terminal Schwann cells produced delayed synaptic elimination with abnormal morphology of the motor endplate, suggesting that Gab1 in both muscles and terminal Schwann cells is required for proper NMJ development. Gab1 in terminal Schwann cells appeared to regulate the number and process elongation of terminal Schwann cells during synaptic elimination. However, Gab2 knockout mice did not show any defects in the development of the NMJ. Considering the role of Gab1 in postnatal peripheral nerve myelination, our findings suggest that Gab1 is a pleiotropic and important component of NRG1 signals during postnatal development of the peripheral neuromuscular system.

Development of a Wearable Pulse Transit Time Monitoring Device / 대한의료정보학회지

OBJECTIVES: We have developed a non.intrusive continuous PTT monitoring system, using a wearable device and wireless communication technology. METHODS: Pulse transit time (PTT) is a non.invasive measurement that shows promise in the continuous monitoring of blood pressure (BP) and the assessment of arterial stiffness. It has potential applications in wearable health monitoring devices. Generally, PTT is measured from the electrocardiogram (ECG) Rwave to a characteristic point on the peripheral pulse by photoplethysmography. However, for home healthcare applications, a system needs to be wearable and wireless. ECG and PPG were sampled at 1200 Hz and transmitted to a personal computer (PC) using Bluetooth communications. Heart rate (HR) and PTT were calculated by the PC from the signals received and waveforms of ECG, PPG, PTT and HR were displayed. RESULTS: In this study, we implemented a system that could be adapted to the wrist and measured ECG and a Photoplethysmogram (PPG). CONCLUSIONS: The wearable continuous PTT monitoring system developed in this study could be useful in home cardiovascular healthcare.

Integrating-Types Biomedical Signal Communication System Combined Power Line and Radio Frequency Communication / 대한의료정보학회지

OBJECTIVES: In order to devise the combination module transmitting bio signal and signal data remotely, as defect of wirewireless combination module was complemented by designing a single combination of wireless module and power supply module, a single system was implemented. METHODS: Currently in case of wireless transmission, it had various problems causing by some factors such as buildings, obstruction, and entanglement of wires and so on. In order to overcome problems of wireless transmission, a single combination module design was researched, which transmits vital signal and sign data using basic electric line installed in the inner building or between others. Even though it was also possible of wireless communication and the internet, in case of a power supply without them, it could be possible to transfer data to underground or top ground in the inner building without any special communication line. RESULTS: Bio signal data was transmitted through a power supply line, a noise problem occurred would be solved by the designed noise filter. The filter showed that noise was cut off about more than 90%. It was also confirmed that the used ECG signals was stably received on transmission experiment. An internal PCB antenna could make the system be wireless communication without the disclosure of an antenna. CONCLUSIONS: In this study, in order to implement a useful system transmitting bio signal and data through wire and wireless management for combination design of wireless module and electrical line module, bio signal transmission system was implemented by design of noise break filter circuit to reduce power noise and PCB internal antenna design.

Effects of Enflurane on Pulse Transit Time / 대한마취과학회지

BACKGROUND: In Anesthetic state, many hemodynamic parameters including blood pressure, heart rate and arterial compliance are changed. Moreover pulse transit time (PTT) is influenced by heart rate, blood pressure changes, and the compliance of the arteries. METHODS: In this study, we investigated PTT changes in patients under enflurane anesthesia. PTT of the finger was measured by photoplethysmography (PPG) and electrocardiography (ECG). PTT values were calculated as the time interval between the peak of the ECG R wave and the peak of the second derivatived of the PPG in the finger tip. RESULTS: ECG amplitude and heart rate increased reflecting hemodynamic chnages after enflurane anesthesia, and the PTT increased after enflurane anesthesia treatment by 16.68 ms (n = 24). Moreover, PTT was found to be inversely proportion to aging. CONCLUSIONS: The increase of PTT in the finger due to relaxation of the arterial wall muscle after enflurane anesthesia was used as an indicator of sympathetic block on muscle tone. This result suggests that PTT is strongly related with anesthetic state. And PTT may be one of useful surrogative methods for anesthetic monitoring, but PTT is unfortunately only qualitative.

Simulation of the Cardiovascular System Using PID Control Model / 대한의료정보학회지

OBJECTIVE: The electric analog circuit model can be used to analyse the various function of the cardio vascular system and the dynamic characteristics on each part of human body. According to the previous studies, viscous resistance, flow inertia, and vascular compliance in the cardiovascular system are analogous to resistance, inductance, and capacitance in electric circuit, so the cardiovascular system models have been represented by the electric circuit models. These approaches were to propose suitable models for the interested part of body and to simulate the various characteristics on the cardiovascular system. METHODS: This paper tried to put the characteristics of morphologic structure into the suggested electric circuit model. After setting parameter values of the model the dynamic characteristics of the cardio vascular system is simulated using VisSim, which is one of the simulation tools. RESULTS: The derived simulation results have represented major cardiovascular functions of normal adults. Also simulation results reflect the variation due to the pathophysiological state. CONCLUSION: The controller by baroreceptor, which is one of controllers to control the cardiovascular system, is appended in the model. The dynamic response characteristics and the procedure to restore blood pressure to normal state was observed by simulation lasted a certain period of bleeding.

The Effect of Peripheral Pulse Arrival Time(PPAT) Measurement in Evaluating Endothelial Function: a Comparison with Flow-Mediated Vasodilation(FMD)

BACKGROUND AND OBJECTIVES: Endothelial dysfunction is an early change in the process of atherosclerosis. To evaluate endothelial function, expensive and specialized medical devices like high-resolution vascular ultrasound are necessary. Therefore, we sought to compare this atherosclerotic parameter of endothelial function using the inexpensive and simple method of peripheral pulse arrival time (PPAT) measurement. SUBJECTS AND METHODS: Before and after meals, we measured PPAT and flow-mediated vasodilation (FMD). Resting PPAT in both arms was measured with a PPAT device that was designed by the authors. Hyperemic effect was tested in both arms after raising the blood pressure to 250 mmHg for 5 minutes by using a blood pressure cuff, after which the cuff was released to 0 mmHg. PPAT was measured within the first 1 minute to observe the hyperemic response. FMD was measured in the same process by 7 MHz high-resolution ultrasound in the left brachial artery. The percent change was calculated from the baseline value and that of the hyperemic response. RESULTS: In low-fat diet, PPAT change was not different (3.8% vs. 4.7%, p>0.05). In high-fat diet, PPAT tended to be shorter, but without statistical significance (4.8% vs. 2.7%, p>0.05). In low-fat diet, the change of FMD was not different (11.7% vs. 11.4%, p>0.05). In high-fat diet, there was a significant difference in FMD (11.4% vs. 6.5%, p<0.05). CONCLUSION: The PPAT measurement could be a method for evaluating endothelial function, but is less sensitive than flow-mediated vasodilation.

Characteristics of Seizures and Neuronal Nitric Oxide Synthase Expression of Hippocampus in Hyperthermia-Induced Seizures of Developing Rat

PURPOSE: Our study was aimed to investigate the characteristics of seizures as well as to determine whether the expression of neuronal nitric oxide synthase expression(nNOS) of hippocampus has an affect in the hyperthermic seizure in developing rat. METHODS: Hyperthermic seizures were repeatedly induced twice a week for four weeks in 20-day old Spraque-Dowley rats. Fifty two rats were used as a hyperthermic group and 30 rats used as a normothermic control group. Hyperthermic seizures were induced in a water bath at 45degreesC+/-1 for 4 min. The characteristics of seizures were recorded. Using western blot, hippocampal nNOS expression was measured in normothermic control, hyperthermic non-seizure, and hyperthermic seizure groups, respectively. RESULTS:Eighty seven percent of hyperthermia exposed rats showed generalized tonic-clonic seizure most frequently. The duration of seizure was ranged from 12 to 145 sec(mean 55 sec) and the latency to seizure ranged from 158 to 240 sec(mean 204 sec). The duration of seizure was prolonged but there was no significant difference in the seizure latency as the rat exposed more number of hyperthermia. Interestingly, the expression level of hippocampal nNOS in hyperthermic seizure and hyperthermic non-seizure groups was not different from each other, however, the expression in these groups was lower than that of the control group. CONCLUSION: Our results indicate that nNOS do not have an affect in this repeated hyperthermic seizures. Further studies are required to clarify a role of nNOS in hyperthermic seizure.

Effect of Ethanol on the Regulation of Smooth Muscle Tone in Rat Aorta

BACKGROUND AND OBJECTIVES: The aim of this study was to determine the effect of ethanol on the regulation of vascular tone. MATERIAL AND METHODS: Using rat aorta ring, isometric contraction and 45Ca uptake were measured. Phorbol 12,13-dibutyrate (PDBu), phenylephrine, KCl were used for the regulation of smooth muscle tone. RESULTS: Ethanol induced transient contraction in rat aorta ring by dose-dependent manner. Ethanol suppressed the dose dependent contractile responses of vascular strip by phenylephrine, KCl and PDBu. Endothelium-dependent relaxation by acetylcholine was inhibited by ethanol. Ethanol depressed 45Ca uptake by high KCl but not by phenylephrine or PDBu in rat aorta. n-butanol selectively suppressed tonic contraction by high KCl, but t-butanol did not at the same concentration of butanol in rat aorta. PDBu-induced contraction was selectively suppressed by n-butanol but not by t-butanol. CONCLUSIONS: These findings suggest that the action of ethanol on phospholipase D is involved in the decreased response of rat aorta strip by vasoconstrictors.

Properties of stretch-activated K+ channels in an G292 osteoblast-like cell / 대한치과교정학회지

K+ -selective ion channels were studied in excised inside-out membrane patches from human osteoblast-like cells(G292). There classes of K+ channels were present and could be distinguished on the basis of conductance. Conductances were 270+/-27 pS, 113+/-12 pS, 48+/-8 pS according to their approximate conductances in symmetrical 140 mM KCI saline at holding potential of -80 mV. It was found that the small conductance (48 pS) K+ channel activation was dependent on membrane voltage. In current-voltage relationship, small conductance K+ channel showed outward rectification, and it was activated by the positive potential inside the membrane. In recordings, single channel currents were activayed by a negative pressure outside the membrane. The membrane pressure increased P(open) of the K+ channel in a pressure-dependent manner. In the excised-patch clamp recordings, G292 osteoblast-like cells have been shown to contain three types of K+ channels. Only the small conductance (48 pS) K+ channel is sensitive to the membrane stretch. These findings suggest that a hyperpolarzing current, mediated in part by this channel, may be associated with early events during the mechanical loading of the osteoblast. In G292 osteoblast-like cells, K+ channel is sensitive to membrane tension, and may represent a unique adaptation of the bone cell membrane to mechanical stress.

A Model of Human Nose and Paranasal Sinuses for the Study of Sinus Ventilation / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The pathogenesis of chronic paranasal sinusitis has been gradually clarified, but there have been conflicting arguments on the ventilation of paranasal sinus. The aim of the present study is to establish an objective, quantitative and reproducible method for the investigation of the ventilation of paranasal sinuses. MATERIALS AND METHODS: With the axial images of high resolution computed tomography, a fine model of human paranasal sinus was made. The model was fitted with pressure sensors, and the pressure changes in the nasal cavity, frontal, maxillary and sphenoid sinuses were measured by pressure sensors and digital physiograph during nasopharyngeal respiration. RESULTS: Results demonstrated negative pressures compared to the atmospheric pressure during inspiration and positive pressures during expiration in the sinonasal cavities, and the highest and lowest pressures were measured in the nasal cavity. CONCLUSION: This study introduces another method for the investigation on the sinus ventilation through a model study. And this study model has demonstrated that the ventilation of paranasal sinuses depends on nasal respiration. Furthermore, the method is useful to evaluate the results of nasal and sinus surgeries in the case of an obstructed ostium, deviated septum or hypertrophied turbinates.