• Preventive Nutrition and Food Science
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• v.10 no.3
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• pp.257-261
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• 2005

Marine sponges are known to produce a number of cytotoxic secondary metabolites. In the course of searching for cytotoxic metabolites from marine organisms, we have evaluated cytotoxic activities of six marine secondary metabolites isolated from various sponges. The cytotoxic compounds 1-6 were isolated by the application of various chromatographic methods, including column chromatography and HPLC. The molecular structures were mostly determined using mass spectrometry (MS) and Nuclear Magnetic Resonance (NMR) Spectroscopy. Furanosestererpenes (compounds 1-3) from Psammocinia sp., cyclitol derivatives (compounds 4 and 5) from Sarcotragus sp., and bromotyrosine-type compound (6) from an association of two sponges Jaspis wondoensis and Poecillastra wondoensis were evaluated for their cytotoxic activity against three cancer cell lines; Hep G2, HeLa, and MCF-7. All tested compounds exhibited cyctoxicity at concentrations ranging from $5\;\mug/mL\;to\;25\;\mug/mL.$ Particularly, among the tested compounds, compound 6 showed the highest potency displaying at least $80\%$ of cytotoxicity at $5\;\mug/mL$ level against all three cancer cell lines.

• Journal of the Korean Society for Railway
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• v.8 no.1
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• pp.41-50
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• 2005

Steel -Concrete Composite two girder railway bridges applying high performance steel with extra thick plate have economic and aesthetic advantages due to the simplification of manufacturing and construction process. However, steel bridges are seldom adopted in domestic railway bridge, since steel bridges are not efficient as R.C bridges considering dynamic characteristics and noise, etc. While highway bridges do not have lower horizontal bracing and larger interval of diaphragm cross beam, railway bridges install lower horizontal bracings to control the torsion due to heavy eccentrical line load. Accurate finite element analysis were performed with the parameters of existence of bracing and bracing shape, with the cross beam interval and stiffness, etc. To find out the effects of secondary members such as horizontal bracings and diaphragms, static md dynamic analysis have been performed by using finite element method. In this study, few member plate-girder bridges are analyzed with variable span lengths to examine the dynamic behavior and limits of damping. And though lateral bracings are members against torsion, but lateral bracing's absence is no big problem. Time history analysis using mode superposition method makes proof of this result.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.5
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• pp.431-440
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• 2021

Background: Neurovascular compression (NVC) is a well-known cause of trigeminal neuralgia (TN). However, patients with idiopathic TN (ITN) do not have evidence of NVC on magnetic resonance imaging (MRI), and other patients may remain asymptomatic despite evidence of NVC on MRI. This suggests that there may be additional risk factors for TN development other than NVC. Although epidemiological factors, such as age and sex differences, are useful for understanding the pathophysiology of TN, detailed statistics for each TN subtype are currently unavailable. Therefore, this study aimed to classify patients with TN into the following groups based on data extracted from past medical records: classical TN (CTN), secondary TN, and ITN. Methods: The characteristics of the groups and their differences were explored. Results: CTN was more common in women than in men, as previously reported, whereas ITN was more common in men than in women. The ratio of pain sites located on the right side of the face was high in all groups. Patients with CTN were also prone to NVC on the asymptomatic side. Conclusion: By investigating TN subtype, it may be possible to elucidate the pathophysiology of TN. This would greatly improve treatment outcomes.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.25 no.3
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• pp.316-321
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• 2023

Developmental venous anomalies (DVAs) are composed of mature venous vessels that lack malformed or neoplastic elements. Although the hemorrhage risk is considered negligible, some patients may have neurological symptoms attributable to acute infarction or intracranial hemorrhage secondary to thrombosis, in the absence of a coexisting cavernous malformation. We report the case of a 42-year-old patient who presented with acute left-hand paresis secondary to a subcortical hemorrhage. This bleeding originated from a DVA in the corticospinal tract area and was surgically drained through an awake craniotomy. To accomplish this, we used a trans-precentral sulcus approach. After the complete removal of the coagulum, small venous channels appeared, which were coagulated. No associated cavernoma was found. Although the main DVA trunk was left patent, no signs of ischemia or venous infarction were observed after coagulating the small venous channels found inside the hematoma cavity. Two weeks after the procedure, the patient's hand function improved, and he was able to resume desktop work. DVA-associated hemorrhage within the cortico-spinal tract could be safely removed with modern awake mapping techniques. This technique allowed the patient to rapidly improve his hand function.

• Journal of Veterinary Clinics
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• v.27 no.2
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• pp.186-189
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• 2010

A 14-year-old neutered female Chihuahua was presented because of seizure episodes and circling to the left side. Based on neurological examination, the lesion was localized on left forebrain. The mass in the left nasal cavity and breaching of the nasal septum were seen magnetic resonance images. And there was a presence of contrast enhanced mass involving the rostral left brain. Based on diagnostic image analysis, this lesion strongly suggested secondary brain tumor infiltrated by nasal cavity. The patient's symptoms were well controlled by a combination therapy of prednisolone and lomustine (CCNU), and survived for two months after diagnosis. This case was definitively diagnosed as a nasal neuroendocrine carcinoma based on histopathological findings. This report describes the clinical findings, imaging characteristics, and pathologic features of secondary brain tumor which caused by infiltration of nasal neuroendocrine carcinoma in a dog.

• Journal of the Korean neurological association
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• v.36 no.4
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• pp.294-301
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• 2018

Background: Neuroimaging can play a crucial role in discovering potential abnormalities to cause secondary headache. There has been a progress in the fields of headache diagnosis and neuroimaging in the past two decades. We sought to investigate neuroimaging findings according to headache disorders, age, sex, and imaging modalities in first-visit headache patients. Methods: We used data of consecutive first-visit headache patients from 9 university and 2 general referral hospitals. The International Classification of Headache Disorders, third edition, beta version was used in headache diagnosis. We finally enrolled 1,080 patients undertook neuroimaging in this study. Results: Among 1,080 patients (mean age: $47.7{\pm}14.3$, female: 60.8%), proportions of headache diagnosis were as follows: primary headaches, n=926 (85.7%); secondary headaches, n=110 (10.2%); and cranial neuropathies and other headaches, n=43 (4.1%). Of them, 591 patients (54.7%) received magnetic resonance imaging (MRI). Neuroimaging abnormalities were found in 232 patients (21.5%), and their proportions were higher in older age groups and male sex. Chronic cerebral ischemia was the most common finding (n=88, 8.1%), whereas 76 patients (7.0%) were found to have clinically significant abnormalities such as primary brain tumor, cancer metastasis, and headache-relevant cerebrovascular disease. Patients underwent MRI were four times more likely to have neuroimaging abnormalities than those underwent computed tomography (33.3% vs. 7.2%, p<0.001). Conclusions: In this study, the findings of neuroimaging differed according to headache disorders, age, sex, and imaging modalities. MRI can be a preferable neuroimaging modality to identify potential causes of headache.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.216-223
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• 2006

The high efficiency full-bridge LLC resonant converter using a contact-less transformer Is proposed for the photovoltaic power generation system. For the series resonance with a series capacitor, the LLC resonant converter utilizes the leakage inductance and magnetizing inductance of a contact-less transformer Unlike the conventional series resonant converter operated to the continuous resonant current at above resonance frequency, the proposed converter operates to the discontinuous resonant current at the narrow frequency control range below resonance frequency. Due to the discontinuous mode resonant current, the proposed converter can be achieved the zero voltage switching (ZVS) in the primary switches and the zero current switching (ZCS) in the secondary rectification diodes without my auxiliary circuit. In this paper, the experimental results of the proposed full-bridge LLC resonant converter using a contact-less transformer are verified on the simulation based on the theoretical analysis and the 150W experimental prototype.

• Journal of Biomedical Engineering Research
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• v.31 no.5
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• pp.401-406
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• 2010

Recently, many implantable medical devices have been developed and manufactured in many countries. In these devices, generally, energy is supplied by a transcutaneous method to avoid the skin penetration due to the power wires. As the most transcutaneous power transmission methods, the electromagnetic coupling between two coils and resonance at a specific frequency has been used widely. However, in case of a transcutaneous power transmitter with a fixed switching frequency to drive an electromagnetic coil, inefficient power transmission and thermal damage by the undesirable current variation may occur, because the electromagnetic coupling state between a primary coil and a secondary coil is very sensitive to skin thickness of each applied position and by person. In order to overcome these defects, a transcutaneous power transmitter of which operating frequency can be automatically tracked into the resonance frequency at each environment has been designed and implemented. Through the results of experiments for different coil surroundings, we have been demonstrated that the implemented transcutaneous power transmitter can track automatically into a varied resonance frequency according to arbitrary skin thickness change.

• Journal of Korean Neurosurgical Society
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• v.29 no.1
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• pp.101-107
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• 2000

Objectives : The evaluation of peripheral nerve injuries has traditionally relied on a clinical history, physical examination, and electrodiagnostic studies. The purpose of the present study was to examine serial magnetic resonance image(MRI) changes following acute muscle denervation under experimental conditions and to identify potential advantages and disadvantages of this use of MRI. Methods : An experimental transection of right sciatic nerve on Spargue-Dawley rats was performed. MRI was performed with T1-weighted spin-echo and STIR sequences. The imaging findings were compared with EMG in order to determine its sensitivity relative to this standard procedure. A simultaneous histopathological study provided information about the morphological basis of the imaging findings. Signal intensities were expressed as a ratio of abnormal to normal. Results : The signal intensity ratio of muscles with the STIR sequence was increased significantly at 2 weeks after sciatic nerve transection(p<0.05), although definite signal change was seen as early as 4 days postdenervation in one. EMG revealed significant denervation potential from 3 days after nerve transection. Diffuse cell atrophy was revealed hostologically at 2 weeks after transection, which was at the same time of significant signal change in MRI. Conclusion : MRI signal changes in denervated muscles secondary to nerve injury correlate with the degree of muscle atrophy on histologic examination. In addition to EMG, MRI can document the course of muscle atrophy and mesenchymal abnormalities in denervation. These results indicate that MRI can play a complementary role in the evaluation of patients with denervation.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.3
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• pp.106-111
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• 2015

Helicobacter pylori (H. pylori) survives in acidic and fluctuating pH conditions of the stomach. The pH effect on H. pylori proteins is important for the advanced understanding of its evolution and viability, although this bacterium has the molecular machinery that neutralizes the acidic condition. HP1492 is known as a conserved NifU-like protein from H. pylori. NifU is a nitrogen fixation protein that mediates the transfer of iron-sulfur (Fe-S) cluster to iron-sulfur proteins like ferredoxin. Commonly, the monomeric reduced state of NifU can be converted to the dimeric oxidized state by intermolecular disulfide bond formation. Because it remains unclear that HP1492 actually behaves as known NifU protein, we first found that this protein can adopt both oxidized and reduced forms using size exclusion chromatography. Circular dichroism experiment showed that HP1492 is relatively well-structured at pH 6.5, compared to other pH conditions. On the basis of the backbone resonance assignment of HP1492, we further characterized the residues that are sensitive to pH using NMR spectroscopy. These residues showing large chemical shift changes could be mapped onto the secondary structure of the protein. Our results could provide the foundation for structural and biophysical studies on a wide spectrum of NifU proteins.