• Progress in Medical Physics
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• v.28 no.4
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• pp.135-143
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• 2017

Chemical Exchange Saturation Transfer (CEST) imaging is a method to detect solutes based on the chemical exchange of mobile protons with water. The solute protons exchange with three different patterns, which are fast, slow, and intermediate rates. The CEST contrast can be obtained from the exchangeable protons, which are hydroxyl protons, amine protons, and amide protons. The CEST MR imaging is useful to evaluate tumors, strokes, and other diseases. The purpose of this study is to review the mathematical model for CEST imaging and for measurement of the chemical exchange rate, and to measure the chemical exchange rate using a 3T MRI system on several amino acids. We reviewed the mathematical models for the proton exchange. Several physical models are proposed to demonstrate a two-pool, three-pool, and four-pool models. The CEST signals are also evaluated by taking account of the exchange rate, pH and the saturation efficiency. Although researchers have used most commonly in the calculation of CEST asymmetry, a quantitative analysis is also developed by using Lorentzian fitting. The chemical exchange rate was measured in the phantoms made of asparagine (Asn), glutamate (Glu), ${\gamma}-aminobutyric$ acid (GABA), glycine (Gly), and myoinositol (MI). The experiment was performed at a 3T human MRI system with three different acidity conditions (pH 5.6, 6.2, and 7.4) at a concentration of 50 mM. To identify the chemical exchange rate, the "lsqcurvefit" built-in function in MATLAB was used to fit the pseudo-first exchange rate model. The pseudo-first exchange rate of Asn and Gly was increased with decreasing acidity. In the case of GABA, the largest result was observed at pH 6.2. For Glu, the results at pH 5.6 and 6.2 did not show a significant difference, and the results at pH 7.4 were almost zero. For MI, there was no significant difference at pH 5.6 or 7.4, however, the results at pH 6.2 were smaller than at the other pH values. For the experiment at 3T, we were only able to apply 1 s as the maximum saturation duration due to the limitations of the MRI system. The measurement of the chemical exchange rate was limited in a clinical 3T MRI system because of a hardware limitation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.131-136
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• 2016

Marine organisms are sources of many bioactive compounds, such as essential fatty acids, essential amino acids, vitamins, and minerals, making them useful candidates for the production of safe bioactive substances. They also synthesize glutamic acid, which can be used to produce γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system (CNS), via fermentation with Lactobacillus brevis BJ-20. This study investigated the degree to which fermented sea tangle (FST) inhibits enzymes such as acetylcholine esterase (AChE) and prolyl endopeptidase (PEP) and affects memory of normal mice using the T-maze test. FST inhibited more than 90% of AChE at 1 mg/mL and 50% of PEP at 8 mg/mL. Oral FST (100 mg/kg) significantly improved performance of normal mice on the T-maze. Therefore, sea tangle fermented with L. brevis BJ20 effectively contributes to memory improvement and might be a useful functional food ingredient.

• Journal of Yeungnam Medical Science
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• v.19 no.2
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• pp.136-143
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• 2002

Even though the nonketotic hyperglycemia is a metabolic disorder, it complicates hemichorea-hemiballism rarely. Moreover, generalized chorea-ballism associated with nonketotic hyperglycemia in diabetes mellitus is very rare, so it has not been reported in Korean literature. Although the precise pathophysiologic mechanisms of these disorders are still poorly understood, deficiency of gamma aminobutyric acid (GABA) in nonketotic hyperglycemia or reduced GABAnergic inhibition by striatal lesion may increase inhibitory output to subthalamic nucleus. These result loss of pallidal inhibition and produce contralateral hemichorea-hemiballism. The striatal lesions, such as transient ischemia with reactive astrocytosis or small amount of petechial hemorrhage, are related with changes of magnetic resonance image (MRI) findings presumably. We report a diabetic old woman who developed generalized chorea-ballismus as a very rare complication of nonketotic hyperglycemia. Her brain MRI showed high signal intensity in left lentiform nucleus and right pallidum on T1 weighted images and low signal intensity in bilateral putamen on T2 weighted images with highly enhanced corresponding lesions on T1 weighted enhancement images.

• Korean Journal of Pharmacognosy
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• v.29 no.3
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• pp.187-192
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• 1998

The ethyl acetate fraction of Uncariae Ramulus et Uncus, which showed anticonvulsant effects against pentylenetetrazole (PTZ) treated mice, were subjected to column chromatography to isolate ursolic acid and hyperin from active eluate. Hyperin decreased the elevated activities of GABA-T and xanthine oxidase and lipid peroxide level dose-dependently in PTZ treated mice brain tissue in vitro, but no effect on superoxide dismutase activity. The effects on such enzyme and component seemed to be related with biosynthesis or metabolism of neurotransmitters.

• Journal of Life Science
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• v.18 no.7
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• pp.940-946
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• 2008

Neurotransmitter transporters, which remove neurotransmittesr from the synaptic cleft, are regulated by second messenger such as protein kinases and binding proteins. Neuronal ${\gamma}-aminobutyric$ acid transporters (GATs) are responsible for removing the inhibitory neurotransmitter ${\gamma}-aminobutyric$ acid (GABA) from the synaptic cleft. ${\gamma}-aminobutyric$ acid transporters 2 (GAT2/BGT1) is involved in regulating neurotransmitter recycling, but the mechanism how they are stabilized and regulated by the specific binding protein has not yet been elucidated. Here, we used the yeast two-hybrid system to identify the specific binding protein(s) that interacts with the C-terminal region of GAT2 and found a specific interaction with the mammalian LIN-7b (MALS-2). MALS-2 protein bound to the tail region of GAT2 but not to other GAT members in the yeast two-hybrid assay. The "T-X-L" motif at the C-terminal end of GAT2 is essential for interaction with MALS-2. In addition, this protein showed specific interactions in the glutathione S-transferase (GST) pull-down assay. An antibody to GAT2 specifically co-immunoprecipitated MALS associated with GAT2 from mouse brain extracts. These results suggest that MALS may stabilize GAT2 in brain.

• Korean Journal of Food Science and Technology
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• v.45 no.3
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• pp.350-355
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• 2013

The quality of fermented dropwort extract (FDE) and fermented dropwort vinegar (FDV) was assessed for free sugar, organic acid and free and total amino acid content. Major organic acids were lactic acid in FDE and acetic acid in FDV. Free sugars in FDE were fructose and glucose, and those in FDV were fructose, sucrose, and maltose. Aspartic acid was the major free amino acid in both FDE and FDV. Additionally, the main free amino acids in FDE were alanine and ${\gamma}$-amino-n-butyric acid (GABA), while those in FDV were arginine and valine. Moreover, to investigate the protective effects of FDE and FDV against oxidative stress induced by t-BHP and $H_2O_2$, C6 cells were treated with FDE or FDV prior to inducing the oxidative damage. FDE and FDV inhibited cell death significantly in a dose-dependent manner. These data imply that FDE and FDV may be effective in neuronal cell protection against oxidative damage.

• Horticultural Science & Technology
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• v.32 no.6
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• pp.845-852
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• 2014

Among various abiotic stress factors, soil salinity decreases the photosynthetic rate, growth, and yield of plants. Recently, many genes have been reported to enhance salt tolerance. The objective of this study was to characterize the Brassica rapa Salt Stress Resistance (BrSSR) gene, of which the function was unclear, although the full-length sequence was known. To characterize the role of BrSSR, a B. rapa Chinese cabbage inbred line ('CT001') was transformed with pSL94 vector containing the full length BrSSR cDNA. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that the expression of BrSSR in the transgenic line was 2.59-fold higher than that in the wild type. Analysis of phenotypic characteristics showed that plants overexpressing BrSSR were resistant to salinity stress and showed normal growth. Microarray analysis of BrSSR over-expressing plants confirmed that BrSSR was strongly associated with ERD15 (AT2G41430), a gene encoding a protein containing a PAM2 motif (AT4G14270), and GABA-T (AT3G22200), all of which have been associated with salt tolerance, in the co-expression network of genes related to salt stress. The results of this study indicate that BrSSR plays an important role in plant growth and tolerance to salinity.

• Journal of Marine Bioscience and Biotechnology
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• v.13 no.2
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• pp.76-85
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• 2021

Crassostrea gigas were fermented using L. brevis BJ20 to prepare fermented oyster extract (FO). The participants of this study were randomly assigned to FO and placebo (CON) groups. The FO group was given 1.0 g of FO supplementation and the CON group was given sucrose each day for eight weeks. The effects of FO supplementation on body composition, muscula r strength, and blood factors associated with muscle growth were assessed. The FO supplement was enriched with arginine (6,183.3 mg), phenylalanine (217.9 mg), leucine (122.6 mg), isoleucine (59.8 mg), valine (16.4 mg), and γ-amino butyric acid (GABA, 1,053.7 mg). The total fat was significantly decreased in the FO group compared with the CON group (p < 0.05). 60D/S Ext.T/Wo rk and 60D/S Flex.T/Work concomitantly with 60D/S Flex.PeakTQ/BW were significantly increase d by FO treatment compared to CON group (p < 0.05). However, posture stability was not significa ntly different between the groups. The levels of angiotensin-converting enzyme were significantly decreased within the FO group (p < 0.05). The FO group showed significantly decreased levels of tumor necrosis factor-α and increased levels of human growth hormone compared with the CON group (p < 0.01). The levels of insulin-like growth factor-1 increased (p < 0.01) in the FO group while that of creatine kinase and triglyceride decreased significantly compared with the CON group (p < 0.05). These results demonstrated that FO supplementation is effective in preventing sarcopenic obesity and maintaining and strengthening muscular function in elderly wom en. Hence, FO supplements can be used as functional ingredients for these benefits.

• Food Science and Preservation
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• v.16 no.6
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• pp.893-899
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• 2009

We compared the physicochemical properties of commercial brown rice vinegar fermented with and without ethanol. The pH and total acidity did not significantly differ between the two types of vinegar. Sugar content, reducing sugar content, and free sugar concentration were higher in commercial brown rice vinegar fermented with ethanol, whereas browning, turbidity, and overall color darkness were higher in vinegar fermented without ethanol. The ratio of acetic acid to total organic acids was 0.94 - 0.96 and 0.97 - 1.00 in commercial brown rice vinegar fermented with or without ethanol, respectively. A higher content of total amino acids, 93.07 - 509.48 ppm, was found in vinegar fermented without ethanol. Fermentation conditions affected the physicochemical properties of brown rice vinegar, as shown by significantly higher $\gamma$-aminobutyric acid (GABA) content in brown rice vinegar fermented without versus with ethanol.

• Biomolecules & Therapeutics
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• v.25 no.2
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• pp.112-121
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• 2017

Drug-induced liver injury (DILI) is the serious and fatal drug-associated adverse effect, but its incidence is very low and individual variation in severity is substantial. Acetaminophen (APAP)-induced liver injury accounts for >50% of reported DILI cases but little is known for the cause of individual variations in the severity. Intrinsic genetic variation is considered a key element but the identity of the genes was not well-established. Here, pre-biopsy method and microarray technique was applied to uncover the key genes for APAP-induced liver injury in mice, and a cause and effect experiment employing quantitative real-time PCR was conducted to confirm the correlation between the uncovered genes and APAP-induced hepatotoxicity. We identified the innately and differentially expressed genes of mice susceptible to APAP-induced hepatotoxicity in the pre-biopsied liver tissue before APAP treatment through microarray analysis of the global gene expression profiles (Affymetrix $GeneChip^{(R)}$ Mouse Gene 1.0 ST for 28,853 genes). Expression of 16 genes including Gdap10, Lpl, Gabra3 and Ccrn4l were significantly different (t-test: FDR <10%) more than 1.5 fold in the susceptible animals than resistant. To confirm the association with the susceptibility to APAP-induced hepatotoxicity, another set of animals were measured for the expression level of selected 4 genes (higher two and lower two genes) in the liver pre-biopsy and their sensitivity to APAP-induced hepatotoxicity was evaluated by post hoc. Notably, the expressions of Gabra3 and Lpl were significantly correlated with the severity of liver injury (p<0.05) demonstrating that these genes may be linked to the susceptibility to APAP-induced hepatotoxicity.