• Animal cells and systems
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• v.2 no.2
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• pp.223-227
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• 1998

We isolated two soluble forms of glutamate dehydrogenase isoproteins, GDH I and GDH II, from bovine brain. The regulation of GDH I and GDH II by phosphorylation and dephosphorylation has been examined in various conditions. There were dose- and time- dependent activation of the GDH isoproteins when phosphorylated by cAMP-dependent protein kinase. The phosphorylated GDH had 1.1 mol of covalently bound phosphate/mol of subunit and a 2-fold increased specific activity. The phosphorylated amino acid was identified as serine. When treated with alkaline phosphatase, the activities of the phosphorylated GDH isoproteins were reduced in dose and time dependent manner and returned to those of unphosphorylated enzymes. There were no significant differences between GDH I and GDH II in their sensitivities to the action of phosphorylation and dephosphorylation demonstrating that the microenvironmental structures of the phosphorylation site in GDH isoproteins are similar to each other, These results results suggest that the inter-conversion between less active form of brain GDH isoproteins and more active form is regulated by phosphorylation through cAMP-dependent protein kineses.

• Environmental Mutagens and Carcinogens
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• v.7 no.2
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• pp.59-64
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• 1987

Cytotoxic and genotoxic potential of monosodium glutamate (MSG) were evaluated in primary cultures of rat hepatocytes. When exposed to liver cell culture continuously for 24 hr, MSG did not show any cytotoxic effects up to 0.5% (w/v) level as determined by Tryphan Blue exclusion and lactic dehydrogenase release test. MSG also did not induce unscheduled DNA synthesis or DNA single-strand breaks in hepatocyte cultures up to 1% level. No synergistic effects of MSG were observed on aflatoxin B$_1$-induced DNA damage when 1% MSG was treated to liver cell culture along with aflatoxin B$_1$.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.4
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• pp.996-1001
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• 2003

It is well known that oxidative stress of reactive oxygen species(ROS) may be a causative factor in the pathogenesis of bone disorder. The purpose of this study was to evaluate the cytotoxicity of oxidative stress. Cell viability by MTS assay or INT assay, activity of glutathione peroxidase(GPx), lipid peroxidation(LPO) activity and cell viablity. And also protctive effect of glutamate receptors against ROS-induced osteotoxicity was examined by protein synthesis, alkaline phosphatase (ALP) activity and lactate dehydrogenase (LDH) activity in cultured rat osteoblasts and osteoclasts. XO/HX decreased cell viability and GPx activity, protein synthesis and ALP activity, but increased LPO activity and LDH activity. In the protective effect, N-methyl-D-aspartate (NMDA) receptor antagonists or AMPA/kainate receptor antagonists such as D-2-amino-5-phosphonovaleric acid (APV), 7-chlorokynurenic acid (CKA), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 6,7-dinitroquinoxaline-2,3-dione (DNQX), NMDA receptor antagonists but AMPA/kainate receptor antagonists showed protective effect on xanthine oxidase (XO) and hypoxanthine (HX) in these cultures by the increse of protein synthesis, ALP activity.

• YAKHAK HOEJI
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• v.39 no.4
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• pp.444-449
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• 1995

Primary cultures of rat cortical and chicken embryonic brain cells were employed to establish a reliable screening method for natural products blocldng or enhancing glutamate-induced neurotoxicity. Exposure of primary cultured rat cortical cells or chicken embryonic brain cells to high dose of glutamate resulted in the fragmentation of neutites and consequent neuronal death. The level of cytoplasmic lactate dehydrogenase(LDH), indicator for cell survival in cultures, was significantly reduced at exposure to glutamate. For the practical application of the methods, series of concentrations of plants extracts and positive control were applied prior to the glutamate insult on primary cultures of rat cortical and chicken embryonic, brain cells. Relative LDH level in cells was measured for the estimation of the effect of the test materials on the glutamatergic neurons. The validity of the present screening method for natural products acting on glutamatergic neurons was examined with dextromethorphan, a known glutamatergic antagonist. The treatment of 100 $\mu{M}$ dextromethorphan prevented the reduction of LDH in rat cortical and chicken embryonic brain cells caused by glutamate insult keeping 60% and 90% of LDH level in normal control, respectively. Above results indicate that primary cultures of rat cortical and chicken embryonic brain cells could be proper systems for the screening of potential natural agents acting on glutamatergic, neurons. Between the two types of cultures, primary culture of chicken embryonic brain cells seemed to be a better system for the primary screening, since it is technically easier and economical compared to that of rat cortical cells.

• International Journal of Oral Biology
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• v.34 no.2
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• pp.97-103
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• 2009

L-trans-pyrrolidine-2,4-dicarboxylate (PDC) is a potent inhibitor of glutamate transporters. In our current study, we investigated whether the neuronal death induced by PDC involves mechanisms other than excitotoxicity in mixed mouse cortical cultures. Cortical cultures at 13-14 days in vitro were used and cell death was assessed by measuring the lactate dehydrogenase efflux into bathing media. Glutamate and PDC both induced neuronal death in a concentration-dependent manner but the neurotoxic effects of glutamate were found to be more potent than those of PDC. Treatment with 10, 100 and 200 ${\mu}$M PDC equally potentiated 50 ${\mu}$M glutamate-induced neuronal death. The neuronal death induced by 75 ${\mu}$M glutamate was almost abolished by treatment with the NMDA antagonists, MK-801 and AP-5, but was unaffected by NBQX (an AMPA antagonist), trolox (antioxidant), BDNF or ZVAD-FMK (a pan-caspase inhibitor). However, the neuronal death induced by 200 ${\mu}$M PDC was partially but significantly attenuated by single treatments with MK-801, AP-5, trolox, BDNF or ZVAD-FMK but not NBQX. Combined treatments with MK-801 plus trolox, MK-801 plus ZVAD-FMK or MK-801 plus BDNF almost abolished neuronal death, whereas combined treatments with trolox plus ZVADFMK, trolox plus BDNF or ZVAD-FMK plus BDNF did not enhance the inhibitory action of any single treatment with these drugs. These results demonstrate that the neuronal death induced by PDC involves not only in the excitotoxicity induced by the accumulation of glutamate but also the oxidative stress induced by free radical generation. This suggests that apoptotic neuronal death plays a role in PDCinduced oxidative neuronal injury.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.296-300
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• 1990

For interspecific portoplast fusion, Brevibacterium flauum lOAHR (Rifr axg his) and Corynebacterium glutamicum 11TS ($Sm-r$ trp) were induced by UV and NTG treatment. The protoplast fusion frequency between E. flavum XOAHR and C. glutamicum llTS was $3.7\times 10^{-6}$ with the lysozyme treatment (300 P $\mu g$ml) for 18 hrs. Genotypes of recombinants were analized as FMM ($Rif^r\; Sm^r$), FA (Rift $Sm^r$ arg), FH ($Rif^r\; Sm^r$ his), FT ($Rif^r\; Sm^r$ trp), FAH ($Rif^r\; Sm^r$ arg trp), FAT ($Rif^r\; Sm^r$ arg trp), and FAHT ($Rif^r\; Sm^r$ arg his trp). FAH 1 produced 12 fold of glutamate production compared to parental type, E. flauum 10AHR. In glutamine productivity, it produced 2.6 fold to parental type, C. glutamicum 11TS. Production of glutamate or glutamine by recombinants was involved in the specific activities of glutamate dehydrogenase (GDH) and glutamine synthetase (GS), respectively.

• Korean Journal of Pharmacognosy
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• v.31 no.1
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• pp.23-27
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• 2000

The effect of seventy kinds of medicinal plants on the activities of GABA-metabolizing enzymes as glutamate dehydrogenase I (GDH I), glutamate dehydrogenase II (GDH II), GABA transaminase (GABA-T), succinic semialdehyde dehydrogenase (SSADH) and succinic semialdehyde reductase (SSAR) were estimated. The following plants extracts from Acori graminei Rhizoma, Longnae Arillus, Gastrodiae Herba, Lycii Fructus, Ligusticum officinale, Ferula assafoetida, Corydalis Tuber, Eucommiae Cortex, Zizyphi spinosi Semen activated the activity of GDH I to more than 35%, and the following ones from Visci Ramulus, Ligusticum officinale, Myristicae Semen, Ferulae Resina, Scolopendrae Corpus, Corydalis Tuber, Eucommiae Cortex, Zizyphi spinosi Semen did that of GDH II. The plant extracts from Cynanchi Radix, Astragali Semen, Angelicae dahuricae Radix, Biotae orientalis Folium, Uncariae Ramulus et Uncus, Polygalae Radix, Cynomorii Herba inhibited that of GABA-T to 35% and over, and the following ones from Hyoscyamus niger, Cynanchi Radix, Acori graminei, Caesalpiniae Lignum, Cannabis Semen, Sedum aizoon, Sedum kamtschaticum, Schisandrae Fructus, Lilii Bulbus, Biotae orientalis Folium, Uncariae Ramulus et Uncus, Myristicae Semen, Akebiae Fructus, Cynomorii Herba, Buddleiae Flos, Mucunae Caulis, Zizyphi Fructus, Paeoniae Radix rubra did that of SSADH to 70% and over; the following ones from, Caesalpiniae Lignum, Sedum kamtschaticum, Schisandrae Fructus, Astragali Semen, Angelicae dahuricae Radix, Dioscorea nipponica, Myristicae Semen, Akebiae Fructus, Cynomorii Herba, Scutellariae Radix did that of SSAR.

• Journal of Radiation Protection and Research
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• v.18 no.2
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• pp.61-69
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• 1993

We examined various enzyme activity changes by intraperitoneal injection uranium in the carp liver. These enzyme activity changes can be used as biochemical indicators of internal exposure to uranium. The results were followings ; 1) Total protein concentration decreased by intraperitoneal injection in the carp liver. 2) Lysosomal acid pretense and ${\beta}-glucuronidase$ activities increased in the liver until sixth intraperitoneal injection of uranium, but Lysosomal acid phosphatase activities decreased in the liver until the sixth injection of uranium. 3) Alkaline phosphatase activities sharply increased and Glutamate oxaloacetate Transaminase activities steadily decreased in the liver until the sixth injection of uranium. 4) Creatine %kinase activities steadily decreased and malate dehydrogenase activities sharply decreased in the liver after the primary injection of uranium. Any malate dehydrogenase activities was not detected after sixth injection of uranium.

• Journal of Life Science
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• v.19 no.7
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• pp.963-967
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• 2009

This study evaluated the neuroprotective effect of extracts from the root bark of Morus alba (MA) against glutamate-induced cytotoxicity in neuronal cells. Glutamate-induced cytotoxicity was shown by MTT reduction assay. The neuroprotective effects of methanol, ethanol, and acetone extracts from MA against glutamate-induced cytotoxicity were measured. Among the three extracts, the methanolic extracts showed the highest protective effect, as determined by the results of an morphological assay, a lactate dehydrogenase release assay. Furthermore, the methanol extracts were fractionated sequentially with hexane, diethyl ether, ethyl acetate, and water layer according to degree of polarity. The hexane fractions exhibited a neuroprotective effect against glutamate-stressed N18-RE-105 cells. Therefore, these results suggest that extracts of MA could be a new potential candidate as a protective substance against glutamate-induced cytotoxicity.

• The Korean Journal of Malacology
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• v.11 no.1
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• pp.51-61
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• 1995

A horizontal starch gal electrophoresis for enzyme proteins extracted from 3 species of Korean planorbid snails; Gyraulus convexiusculus, Hippeutis cantori and Segmentina hemisphaerula was carried out in order to elucidate their genetic relationships.The results from 12 enzymes employed in three different kinds of buffer systems are summarized as follows:1) Two loci from each enzyme of aldehyde oxidase, esterase, glucose phosphate isomerase. isocitrate dehydrogenase, leucine aminopeptidase, malate dehyogenase, peptidase and xanthine oxidase were detected, and only one locus was observed from each of the following four enzymes: 6-phosphogluconate dehydrogenase, glyceraldehyde-phosphate dehydrogenase, glutamate oxaloacetate transaminase and glycerol-3-phosphate dehydrogenase.2) Most of loci in 3 species of planorbid snails employed showed homozygous and monomorphic banding patterns and some of them were specifis as genetic markers among different species. However, a few of loci (EST-1. EST-2 and GPI-2)showed polymorphic banding patterns. 3)Hippeutis cantori and Segmentina hemisphaerula were more closely clustered in a dendrogram with the genetic iddentity value of 0.431, and these two species were lineated with Gyraulus convexiusculus as another cluster at the value of 0.294.In summarizing the above results, three species of Korean planorbid snails employed in this study mostly showed monomorphic enzyme protein banding patterns and genetic differences specific among 3 species.