• BMB Reports
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• v.28 no.4
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• pp.293-300
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• 1995

The radical centers detected in the reaction of metmyoglobin (MetMb) with hydrogen peroxide ($H_2O_2$) have been studied by using a spin trapping technique. A broad 5-line asymmetric electron spin resonance (ESR) spectrum, with $2A_{max}=4.07\;mT$ and $2A_{min}=2.97\;mT$, obtained after incubation of MetMb with $H_2O_2$ in the presence of a spin trap, 5,5-dimethyl pyrroline-N-oxide (DMPO) was gradually weakened with time and disappeared completely by 6 min after addition of guanidine-HCl (14 M). When a higher concentration (6 M) of the agent was added, the signal disappeared within 40 see and the DMPO/OH signal appeared immediately. Then, a new 8-line signal with similar intensities grew gradually and was fixed by 45 min, coexisting with the DMPO/OH signal. This new signal was found to be composite, consisting of two different radical species. One of the 6-line signals, with $a_N$ 1.49 mT and $a_H$ 0.988 mT, was assigned to the DMPO/phenoxyl radical adduct. The second 6-line signal with $a_N$ 1.55 mT and $a_H$ 2.22 mT was assigned to carbon-centered radical adduct. When 3,3,5,5-tetramethylpyrrolin-N-oxide (TMPO), was employed in the place of DMPO, another broad asymmetric 5-line signal was detected with $2A_{max}=3.99\;mT$ and $2A_{min}=3.04\;mT$, which is virtually identical to that obtained from the DMPO system The shape of the spectrum of the TMPO adduct changed drastically, with lapse of time resulting in a broad singlet after 40 min. The broad singlet was assigned to the porphyrin radical adduct. Incubation of globin with Fenton reagent in the presence of DMPO initially gave a DMPO/OH signal. Then, a new 12-line signal began to grow after one minute and fixed after 15 min. coexisting with the DMPO/OH signal, This 12-line signal was assigned to DMPO/phenoxyl with $a_N$ 1.47 mT, $a_{{\beta}H}$ 0.99 mT and $a_{{\gamma}H}$ 0.13 mT. A minor concentration of carbon-centered radical adduct was also detected. This radical composition is identical to that of guanidine HCl treated MetMb/DMPO/$H_2O_2$ system, indicating that the radical producing conditions are somehow common in both systems. Heme iron can be released by excess $H_2O_2$ in the MetMb/$H_2O_2$ system, providing for Fenton reagent. When MetMb was pretreated with tyrosine blocking agent, $KI_3$ the broad 5.line MetMb-derived signal was not detected in the MetMb/DMPO/$H_2O_2$ system, whereas no such effect was detected on such system of Hb in which the radical center was assigned to cysteine residue not tyrosine, indicating that tyrosine residue is a main radical center produced in the MetMb/$H_2O_2$ system Thus, the present data strongly support the previous indication that the apomyoglobin-derived radical center formed in the reaction of MetMb with $H_2O_2$ is a tyrosine residue.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.221-226
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• 2010

Physical detection methods, photostimulated luminescence (PSL), thermoluminescence (TL) and electron spin resonance (ESR) were applied to detect electron beam-irradiated agricultural products, such as red pepper, black pepper, raisin, walnut, beef seasoning and pistachio. The absorbed irradiation doses for representative samples were controled at 0, 1, 3, 5 and 10 kGy. PSL values for non-irradiated samples were <700 counts/60s (lower threshold, $T_1$) except beef seasoning, whereas those of irradiated samples were more than 5,000 photon counts, upper threshold ($T_2$) in black pepper, raisin, and beef seasoning and intermediates values of $T_1-T_2$ in red pepper, walnut, and pistachio. Minerals seperated from the samples for TL measurement showed that non-irradiated samples except pistachio (TL ratio, 0.12) were characterized by no glow curves situated at temperature range of $50{\sim}400^{\circ}C$ with TL ratio (0.01~0.08), while irradiated samples except pistachio at only 1 kGy (TL ratio, 0.08) indicated glow curve at about $150{\sim}250^{\circ}C$ with TL ratio (0.28~3.10). ESR measurements of irradiated samples showed any specific signals to irradiation. The samples of both red pepper and pistachio were produced specific signals derived from cellulose radicals as well as single line signals for black pepper and walnut, and multiple signals derived from crystalline sugar radicals for raisin and beef seasoning. In conclusion, The ESR methods can apply for detection of pistachio exposed to electron beam but PSL and TL are not suitable methods. Furthermore, TL and ESR suggeted that both techniques were more useful detection method than PSL to confirm whether red pepper, walnut and beef seasoning samples have been exposed to electron beam.

• Journal of the Korean Society of Visualization
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• v.14 no.3
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• pp.38-45
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• 2016

Separation of particles based on different sizes, detection of pathogenic bacteria and isolation of leukocytes from whole blood are typical applications of spiral or helical microchannels. The present study focuses on developing a CD4+ T-cell counting device for monitoring HIV/AIDS patients with the aid of a helical minichannel used for a sample cartridge. For the experiment, $10{\mu}m$ sized microbeads were used for visualization with a fluorescence imaging system. Alignment of microbeads was investigated in a stationary and spinning sample cartridge filled with glycerol-water mixtures of different densities. The helical minichannel was spun using a DC motor controlled by an Arduino board with a Bluetooth shield. It was found that when the sample cartridge was made stationary, no bead alignment was achieved for a medium with density (0% and 20% glycerol) lower than that of the beads, but when it was spun at 2000-3000 rpm for 1-4 min, an alignment was obtained at the top of the channel facilitating optical detection and enumeration of those microbeads. Since an alignment of microbeads was achieved for a medium with density as that of blood plasma, the same approach can be applied for aligning and counting CD4+ T-lymphocytes in whole blood samples collected from patients.

• Journal of Food Hygiene and Safety
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• v.15 no.1
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• pp.1-4
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• 2000

Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose on the ESR signal intensity of irradiated crabs and the stability of these radicals under 9 weeks of storage. Swimming and small crabs were irradiated with doses of 0, 1, 3, 5 and 7 kGy using a Co-60 irradiator at ambient temperature. A claw, a walking leg and a cars- pace of the crab pieced and dried were placed in a resonant quart tube within an EPR X-band spectrometer. The irradiated crabs presented an asymmetric absorption in shape at g$_1$=2.002 $\pm$ 0.003 and g$_2$=1.998$\pm$0.005, and were different from the non-irradiated ones. The intensity of the ESR signals was greatest in the claw, intermediate in the carapace and lowest in the walking leg. Samples given low and high doses of irradiation could also be distinguished. The ESR signal after irradiation was stable, even after a 9-week storage.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.57-61
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• 2002

Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose and storage time on the free radical concentrations in gamma-irradiated dried seasoning powder. Seasoning powders of dried squid flavor, shrimp flavors, kimchi flavor, spicy beef soup flavor and soy sauce flavor were irradiated with doses of 0, 1, 3, 5, 7 and 9 kGy at room temperature using a Co-60 irradiator. Characteristic signals of free radicals were observed in all the irradiated samples of this experimental while these signals were not detected in non-irradiated samples. Since the free radical concentrations linearly increased with the applied doses (1~9 kGy), highly positive correlation coefficients ($R^2$ = 0.9285~0.9965) were obtained between irradiation doses and free radical concentrations during all the storage times. Free radical concentrations of the irradiated flavored seasoning powder did not change even at 16 weeks of storage at room temperature, while those of dried squid, shrimp and spicy beef soup flavors decreased until 2 weeks of storage after irradiation with 5 kGy or over, and these of soy cause flavors slowly decreased until 8 weeks of storage after irradiation with 3 kGy or over. Although the free radical concentrations decreased with storage times, the characteristic signals of the irradiated seasoning powders of dried squid, shrimp, spicy beef and soy sauce flavors were observed even after 16 weeks of storage at room temperature.

• Preventive Nutrition and Food Science
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• v.9 no.4
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• pp.317-323
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• 2004

Photostimulated Luminescence (PSL), Electron Spin Resonance (ESR) and Thermoluminescence (TL) analysis were conducted to detect irradiation treatment of imported whole and ground spices. The screening by PSL detected no irradiation treatment, except un the ground thyme and bay leaves which exhibited photon counts in the intermediate level. Irradiation of the two spices was detected after irradiating them at 1.0, 3.0, 5.0 and 10.0 kGy, and then subjecting them to PSL analysis, which resulted in the significantly low photons of non-irradiated spices compared to that at 1.0 kGy, indicating that the photon counts varied depending on the amount of inorganic mineral debris in the spices. To confirm a successful detection by using PSL, ESR and TL methods, some spices were selected, irradiated at 5.0 and 10.0 kGy, and subjected to the detection methods. PSL identified the irradiated spices except the cassia, which showed very weak PSL sensitivity, but was identified by ESR analysis. Also, the ESR and TL exhibited the typical signals induced by irradiation treatment and were able to successfully detect all of the irradiated spices. In addition, we found a positive correlation between the intensity of ESR and TL signals and irradiation doses.

• Investigative Magnetic Resonance Imaging
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• v.26 no.1
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• pp.32-42
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• 2022

Purpose: To evaluate the clinical benefit of 2D contrast-enhanced T2 fluid-attenuated inversion recovery (CE-T2 FLAIR) image for detecting leptomeningeal metastasis (LM) in the brain metastasis work-up for lung cancer. Materials and Methods: From June 2017 to July 2019, we collected all consecutive patients with lung cancer who underwent brain magnetic resonance image (MRI), including contrast-enhanced 3D fast spin echo T1 black-blood image (CE-T1WI) and CE-T2 FLAIR; we recruited clinico-radiologically suspected LM cases. Two independent readers analyzed the images for LM in three sessions: CE-T1WI, CE-T2 FLAIR, and their combination. Results: We recruited 526 patients with suspected lung cancer who underwent brain MRI; of these, we excluded 77 (insufficient image protocol, unclear pathology, different contrast media, poor image quality). Of the 449 patients, 34 were clinico-radiologically suspected to have LM; among them, 23 were diagnosed with true LM. The calculated detection performance of CE-T1WI, CE-T2 FLAIR, and combined analysis obtained from the 34 suspected LM were highest in the combined analysis (AUC: 0.80, 0.82, and 0.89, respectively). The inter-observer agreement was also the highest in the combined analysis (0.68, 0.72, and 0.86, respectively). In quantitative analyses, CNR of CE-T2 FLAIR was significantly higher than that of CE-T1WI (Wilcoxon signed rank test, P < 0.05). Conclusion: Adding CE-T2 FLAIR might provide better detection for LM in the brain-metastasis screening for lung cancer.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.683-690
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• 2009

The purpose of this study is to evaluate the usefulness of high-b-values diffusion weighted magnetic resonance imaging for the preoperative detection of focal rectum cancers. 60patients with diffusion weighted imaging were evaluated for the presence of rectal cancers. Forty were male and twenty were female, and their ages ranged from 38 to 71 (mean, 56) years. Used equipment was 1.5Tesla MRI((GE, General Electric Medical System, Excite HD). Examination protocols were used the fast spin echo T2, T1 weighted imaging. All examination protocols were performed by the same location with diffusion weighted imaging for accuracy detection. The b-values used in DWI were 250, 500, 750, 1000. 1500, 2000$(s/mm^2)$. The rectum, bladder to tumor contrast-to-noise ratio (CNR) of MR images were quantitativlely analyzed using GE software Functool tool, four experienced radiologists and three radiotechnologists qualitatively evaluated image quality in terms of image artifacts, lesion conspicuity and rectal wall. These data were analysed by using ANOVA and Freedman test with each b-value(p<0.05). Contrast to noise ratio of rectum, bladder and tumor in b-value 1000 were 27.21, 24.44, respectively(p<0.05) and aADC value was $0.73\times10^{-3}$. As a qualitative analysis, the conspicuity and discrimination from the rectal wall of lesions were high results as $4.0\pm0.14$, $4.4\pm0.16$ on b-value 1000(p<0.05), image artifacts were high results as $4.8\pm0.25$ on b-value 2000(p<0.05). In conclusion, DWI was provided useful information with depicting the pre-operative detection of rectal cancers, High-b-value 1000 image was the most excellent DWI value.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.609-613
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• 2015

The onset of instability induced by impulsive spin-down of the rigid-body flow placed in the gap between two coaxial cylinders is analyzed by using the energy method. In the present stability analysis the growth rate of the kinetic energy of the base state and also that of disturbances are taken into consideration. In the present system the primary flow is a transient, laminar one. But for the Reynolds number equal or larger than a certain one, i.e. $Re{\geq}Re_G$ secondary motion sets in, starting at a certain time. For $Re{\geq}Re_G$ the dimensionless critical time to mark the onset of vortex instabilities, ${\tau}_c$, is here presented as a function of the Reynolds number Re and the radius ratio ${\eta}$. For the wide gap case of small ${\eta}$, the transient instability is possible in the range of $Re_G{\leq}Re{\leq}Re_S$. It is found that the predicted ${\tau}_c$-value is much smaller than experimental detection time of first observable secondary motion. It seems evident that small disturbances initiated at ${\tau}_c$ require some growth period until they are detected experimentally.

• Clinical and Experimental Pediatrics
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• v.63 no.3
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• pp.88-95
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• 2020

Accurate localization of the seizure onset zone is important for better seizure outcomes and preventing deficits following epilepsy surgery. Recent advances in neuroimaging techniques have increased our understanding of the underlying etiology and improved our ability to noninvasively identify the seizure onset zone. Using epilepsy-specific magnetic resonance imaging (MRI) protocols, structural MRI allows better detection of the seizure onset zone, particularly when it is interpreted by experienced neuroradiologists. Ultra-high-field imaging and postprocessing analysis with automated machine learning algorithms can detect subtle structural abnormalities in MRI-negative patients. Tractography derived from diffusion tensor imaging can delineate white matter connections associated with epilepsy or eloquent function, thus, preventing deficits after epilepsy surgery. Arterial spin-labeling perfusion MRI, simultaneous electroencephalography (EEG)-functional MRI (fMRI), and magnetoencephalography (MEG) are noinvasive imaging modalities that can be used to localize the epileptogenic foci and assist in planning epilepsy surgery with positron emission tomography, ictal single-photon emission computed tomography, and intracranial EEG monitoring. MEG and fMRI can localize and lateralize the area of the cortex that is essential for language, motor, and memory function and identify its relationship with planned surgical resection sites to reduce the risk of neurological impairments. These advanced structural and functional imaging modalities can be combined with postprocessing methods to better understand the epileptic network and obtain valuable clinical information for predicting long-term outcomes in pediatric epilepsy.