Hyun Sook Lee

Detection of BRAFV600E mutation on fine needle aspiration specimens of thyroid nodule refines cyto‐pathology diagnosis, especially in BRAFV600E mutation‐prevalent area

Backgroundu2002 Between 10 and 30% of the fine needle aspiration biopsies (FNABs) of thyroid nodules are diagnosed as ‘indeterminate’. A molecular diagnostic method is needed to reduce unnecessary surgery in this group. In Korea, most thyroid cancer is the classic papillary type and the BRAFV600E mutation is highly prevalent.

Analysis of differential BRAF(V600E) mutational status in multifocal papillary thyroid carcinoma: evidence of independent clonal origin in distinct tumor foci

Papillary thyroid cancers often occur as multiple foci. Multifocal cancers have been considered to have a poor prognosis because they are thought to be the consequence of intrathyroidal spread of the papillary cancer. However, to the authors knowledge there has been little investigation into whether multifocal thyroid papillary carcinomas arise from the intrathyroidal spread of a single carcinoma or from independent primary tumors. To answer this question, the BRAFV600E mutational status of individual tumor foci was examined. This approach was justified because in the Korean population a high proportion (65%) of papillary carcinomas harbor the BRAF mutation.

Involvement of the protein kinase C pathway in thyrotropin-induced STAT3 activation in FRTL-5 thyroid cells.

The binding of thyrotropin (TSH) to the TSH receptor (TSHR) activates two signaling pathways: the cAMP-protein kinase A (PKA) and the protein kinase C (PKC) systems. We have recently demonstrated that TSH activates the Janus kinases (JAK)/signal transducer and activator of transcription (STAT) pathway via TSHR. This study aimed to investigate whether the cAMP/PKA or the PKC system is involved in STAT3 activation in response to TSH. Treatment with TSH activated STAT3 phosphorylation in FRTL-5 thyrocytes and human TSHR-expressing Chinese hamster ovary cells. TSH-induced STAT3 activation was inhibited by a blocking antibody directed against TSHR that was isolated from patients with primary myxoedema. Increased intracellular cAMP activated STAT3 but inhibition of PKA did not affect STAT3 activation. On the other hand, the PKC stimulant PMA induced STAT3 phosphorylation and the PKC inhibitors inhibited it. Moreover, inhibition of PKC blocked STAT3 activation induced by a stimulator of cAMP. Our data suggest that TSH activates STAT3 via TSHR and cAMP- and PKC-dependent pathways, and provide evidence that PKC may be involved in the pathway downstream from cAMP.

Design of Alternating Magnetic Field Stimulator Using Duty Factor

We have developed an alternating magnetic field stimulation system consisting of a switched-mode power supply and a digital control circuit which modulates a duty ratio to maintain a magnetic field intensity of a few mT even while the frequency increases up to 4 kHz with a controllable coil temperature below 30 oC in air. This duty ratio modulation and water circulation are advantageous for cell culture under ac-magnetic field stimulation by preventing the incubator from exceeding a cell-viable temperature of 37 oC. Although the temperature of the coil when subjected to a sinusoidal voltage rapidly increased, that of our system modulated by the duty factor did not change. This is a potentially valuable method to investigate the effects of intermediate frequency magnetic field stimulation on biological entities such as cells, tissues and organs.

Assessment of Pulsed Magnetic Field Stimulus by Using Finger Photoplethysmogram and Pressure Pulse Waveform

Photoplethysmogram (PPG) and pressure pulse waveform (PPW) were compared and evaluated for the efficacy of stimulating knuckles by using the pulsed magnetic field. Both signals were observed simultaneously while the knuckles were exposed for 10 min to the pulsed magnetic field, with maximum field intensity of 0.8 T and transition time of 0.126 msec. After 5 min stimulation of the knuckles, the results showed that the aging indexes calculated from the second derivative of the PPG were increased from ?1.913 to 0.072, and that of the PPW from ?0.063 to 0.387. However, for the relatively long-term stimulation for 10 min, we found that the values of both the aging indexes of the second derivatives and augmentation index of the PPW returned to the starting level. The changes observed in characteristic factors such as the aging indexes of the second derivatives and augmentation index of the PPW indicate the potential of pulsed magnetic field stimulation as a therapeutic method for the treatment of patients with peripheral vascular disease.

An Analytical Comparison in Electoencephalography and Electrocardiography under Pulsed Magnetic Field and Acupuncture Stimulus on Acupoint PC9

We have investigated the changes of electroencephalography (EEG) and electrocardiography (ECG) under pulsed magnetic field (PMF) and acupuncture stimulus on acupoint PC9. In order to compare quantitatively the effect of PMF and acupuncture stimulus, the difference of alpha activities are calculated from EEG spectra, and the spectrum curves of ECG were analyzed in the frequency domain of heart rate variability (HRV). The increase of alpha activities after both stimuli could be explained that the impulse of stimulus on PC9 might pass through sensory nerve following meridian and approach the cerebral cortex, causing the central nervous system (CNS) to be activated for pacifying emotion and calming the mind. The decrease in sympathovagal activity of HRV after both stimuli indicates that parasympathetic nerves were activated and the sympathetic nerves were in constrained condition. These findings suggest that PMF could be patient-friendly alternative non-invasive medical treatment for influencing human physiology, in comparison with acupuncture inserting the needle and inducing nervous and anxious state to subject.

Analysis of Electroencephalogram and Electrocardiogram at an Acupoint PC9 during Pulsed Magnetic Field Stimulus

We investigated the effects of pulsed magnetic fields (PMF) stimulus on electroencephalogram (EEG) alpha activity and heart rate variability (HRV) from electrocardiogram (ECG) measurements with various stimulus durations at acupoint PC9. The alpha activity in the EEG and the ratio of low frequency power and high frequency power (LHR) in the HRV, a reflection of sympathovagal activity, were increased and decreased, respectively, after PMF stimulus of 3 min. Our spectral analysis quantitatively proved that the changes in the EEG alpha activity were consistent with an autonomic function in the ECG. These findings suggest that appropriate PMF stimulus results in the same effect as that of acupuncture applied to the acupoint PC9, which is closely related to the parasympathetic activity of the autonomic nervous system.

The Effect of Magnetic Field Direction on the EEG and PPG Obtained from Pulsed Magnetic Stimulus at Acupoint PC9

Compared to acupuncture, the pulsed magnetic field (PMF) stimulus is a useful tool for treatment of many physical conditions and health maintenance due to its advantages as a noninvasive and nontoxic medical treatment. The purpose of this study was to investigate the effect of PMF stimulus direction at PC9 on the alpha activity of electroencephalogram (EEG) and vascular aging calculated from photoplethysmograph (PPG). It can be concluded that the direction of PMF stimulus affects the increase of alpha activity of EEG and PPG, indicating the vascular stiffness and the sclerosis level of blood vessels weakly relevant to the direction of PMF stimulus.

Comparative Analysis of Photoplethysmography under Pulsed Magnetic Field and Low Level Laser Stimulus: Motivation for Blood Flow Increase using Stimulus on Acupoint LI4 (Hegu)

The purpose of this study was to investigate the effect of pulsed magnetic field (PMF) and low frequency low level laser (LFLLL) stimuli on acupoint LI4 (Hegu) using photoplethysmography (PPG). Our PMF system was designed to generate maximum intensity of 0.20 T at a transition time of 0.16 ms, with pulse intervals of 1 Hz. The diode laser with wavelength of 650 nm and power of 5 mW was also employed. It was observed the change of the pulsating blood volume through measuring PPG signals from both hands. These results imply that stimulating acupoint LI4 with PMF and LFLLL improves the circulation of peripheral vascular system. In particular, PMF stimulation brings a big improvement of the blood flow even with short term stimulation of 3-4 minutes compared to LFLLL stimulus.

Magnetization Angle and Thickness Dependence of Perpendicular Exchange Anisotropy in [Pd/Co] n /FeMn Films

The magnetization angle and thickness dependence of magnetic anisotropy in the exchange-biased [Pd/Co]×5/FeMn multilayers with an out-of-plane anisotropy were investigated to determine the origin of perpendicular exchange biasing. As the Co thickness increased to 1.5 ㎚ in the [Pd(0.8 ㎚)/Co(t)]×5/FeMn(120 ㎚) films, the hysteresis loops were converted from square loops at a thin Co (＜0.4 ㎚) to complicated round ones at a thick Co. The irregularly asymmetric step (IAS) at the left top of the loop appeared in the loop of the 0.6-㎚ Co film due to an inhomogeneity in the exchange anisotropy. As the Pd thickness increased to 1.6 ㎚, the step disappeared, and the perpendicular magnetic anisotropy was maximized in the Co thickness between 0.6 and 0.9 ㎚. The conversion of the magnetization loop along the magnetization angle coincided with the equation H (eff) = Ho cos θ. The IAS of the 0.8-㎚ Pd film disappeared after thermal annealing up to 200℃ under an external magnetic field.