• Journal of the Korean Chemical Society
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• v.24 no.4
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• pp.315-321
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• 1980

A steady-state kinetic study on a dye-coupled cytoplasmic polyol dehydrogenase from G. melanogenus was carried by the initial velocity measurements in the direction of the polyol oxidation and the product inhibition by D-fructose. For the initial rate experiments, D-mannitol and D-sorbitol were employed as the specific polyol substrates and 2,6-dichlorophenolin-dophenol (DPIP) as the specific cofactor substrate for the enzyme. When the polyol and DPIP were examined by varying one of substrates and by fixing the second, the corresponding reciprocal plots showed the typical parallel pattern. This suggests that the enzyme from G. melanogenus proceeds by a Ping Pong Bi-Bi mechanism in which the polyol may account as the first reactant-in, and the ketose formed as the first product-out, respectively. The product inhibition patterns obtained by D-fructose (one no-inhibition, one non-competitive, and two competitive) may also provide an additional conformatory evidence for the above mechanism. Based on the kinetic parameters obtained, it was also suggested that the rate-limiting step in the direction of polyol oxidation is associated with the release of the ketose from the Enzyme${\cdot}$Polyol complex.

• Korean Journal of Biological Psychiatry
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• v.23 no.4
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• pp.193-198
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• 2016

Objectives Obsessive-compulsive disorder (OCD) and schizophrenia have many common clinical and neurocognitive features. However, not all of them share the same underlying mechanism. The aim of this study was to discover evidences that indicate a pathophysiological mechanism specific to OCD by comparing correlations of quantitative electroencephalography (QEEG) patterns and neurocognitive function in patients with OCD and schizophrenia. Methods Resting-state QEEG data of total 265 patients were acquired retrospectively and parameters such as absolute power, relative power and peak frequency were analyzed from the data. Stroop test and Trail Making Test results as well as demographic features were reviewed for this study. The correlation of neurocognitive functions and brain electrical activities in each group were assessed and compared by correlation analysis. Results Compared with the OCD group, the schizophrenia group performed poorly in neurocognitive tests. Mean values of QEEG parameters in patients with OCD and schizophrenia did not show significant differences. Both absolute and relative power of alpha rhythm in central and frontal regions showed significant positive correlation with Stroop test results in OCD patients. Conclusions Findings in this study shows distinctive correlations between frontal executive dysfunction and frontal alpha rhythm in the OCD patients, both of which might be a candidate for endophenotype underlying obsessive rumination.

• BMB Reports
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• v.36 no.4
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• pp.337-343
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• 2003

Rhus verniciflua Stokes (RVS) has been used as a traditional herbal medicine. Several earlier studies indicated that an ethanol extract of RVS has both anti-oxidant and anti-tumor properties, although the mechanism for the activity remains to be elucidated. In this report, we prepared a highly purified ethanol extract from RVS, named REEE-1 ($\underline{R}$hus $\underline{e}$thanol $\underline{e}$luted $\underline{e}$xtract-1), and investigated the mechanism involved in its growth-inhibitory effect on the human B and T lymphoma cell lines, BJAB and Jurkat, respectively. Results from tritium uptake proliferation assays showed that the proliferative capacities of both BJAB and Jurkat cells were strongly suppressed in the presence of REEE-1. This was further confirmed through trypan blue exclusion experiments that revealed a dose-dependent decrease in viable cell numbers after REEE-1 treatment. REEE-1-mediated suppression of cell growth was verified to be apoptotic, based on the increase in DNA fragmentation, low fluorescence intensity in nuclei after propidium iodide staining, and the appearance of DNA laddering. In particular, REEE-1 exerted its anti-oxidant activity through the inhibition of hydroxyl radical-mediated degradation by iron ion chelation rather than direct scavenging of hydroxyl radicals. Furthermore, REEE-1 was revealed to be a potential scavenger of superoxide anions. Collectively, our findings suggest that REEE-1 is a natural anti-oxidant that could be used as a cancer chemo-preventive and therapeutic agent.

• Korean Journal of Biological Psychiatry
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• v.5 no.2
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• pp.227-234
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• 1998

Objective : Many evidences suggest that patients with bipolar disorder have functional abnormalities in their postreceptor signal transduction pathways, and mood stabilizing effect of lithium is exerted by modulating this dysfunctioning system. Carbamazepine, an antiepileptic agent, is also known to be effective in the treatment and prevention of bipolar disorder. But the precise mechanism of action of the drug is still poorly understood. This study was performed to elucidate the possible therapeutic mechanism of carbamazepine. Method : The effects of chronic carbamazepine administration on protein kinase A and protein kinase C activities in frontal cortex of rat brain after 2 weeks of drug administration were measured and compared with those of control subjects. Results : Mean(${\pm}SE$) value of activity(phosphate transfer ${\mu}mol/mg$ of $protein{\cdot}min$) of protein kinase A in control and test group was $0.249563{\pm}0.036$ and $0.539853{\pm}0.078$, and that of protein kinase C was $0.654817{\pm}0.053$ and $1.146205{\pm}0.052$ respectively, being increased in test group. And differences between the two groups were statistically significant for both enzymes(protein kinase A ; p<0.01, protein kinase C ; p<0.001). Conclusion : These results show that chronic carbamazepine administration increases protein kinase A and C activities, and concerning the possible mode of therapeutic action in bipolar disorder it is suggested that enhanced enzymes phosphorylate receptor-G-protein-effector complexes to dampen hyperfunctioning neuronal activity and thus stabilize the system.

• BMB Reports
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• v.49 no.5
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• pp.245-246
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• 2016

The level and activity of critical regulatory proteins in cells are tightly controlled by several tiers of post-translational modifications. HIF-1α is maintained at low levels under normoxia conditions by the collaboration between PHD proteins and the VHL-containing E3 ubiquitin ligase complex. We recently identified a new physiologically relevant mechanism that regulates HIF-1α stability in the nucleus in response to cellular oxygen levels. This mechanism is based on the collaboration between the SET7/9 methyltransferase and the LSD1 demethylase. SET7/9 adds a methyl group to HIF-1α, which triggers degradation of the protein by the ubiquitin-proteasome system, whereas LSD1 removes the methyl group, leading to stabilization of HIF-1α under hypoxia conditions. In cells from knock-in mice with a mutation preventing HIF-1α methylation (Hif1α^KA/KA), HIF-1α levels were increased in both normoxic and hypoxic conditions. Hif1α^KA/KA knock-in mice displayed increased hematological parameters, such as red blood cell count and hemoglobin concentration. They also displayed pathological phenotypes; retinal and tumor-associated angiogenesis as well as tumor growth were increased in Hif1α^KA/KA knock-in mice. Certain human cancer cells exhibit mutations that cause defects in HIF-1α methylation. In summary, this newly identified methylation-based regulation of HIF-1α stability constitutes another layer of regulation that is independent of previously identified mechanisms.

• Korean Journal of Medicinal Crop Science
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• v.21 no.2
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• pp.136-141
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• 2013

Chelidonium majus (CM) contains several isoquinoline alkaloids that have been reported to have various biological activities such as anti-inflammatory, antimicrobial, antioxidant, immune-modulatory, and antitumoral. It has been reported that the extract of CM had an antioxidant potential, however the mechanism has not been verified. In this study, we found that CM extract activated FOXO3a. FOXO3a is a transcription factor that involved in various biological processes such as cell cycle arrest, apoptosis, DNA repair, and ROS detoxification. Transcriptional activities of FOXO3a were regulated by post-translational modifications including phosphorylation, acetylation, and ubiquitination. Protein level of FOXO3a was increased by CM extract. Promoter activities of FOXO-transcriptional target genes such as MnSOD, p27 and GADD45 were activated by CM extract in a dose dependent manner. In addition, protein level of MnSOD, major antioxidant enzyme, was increased by CM extract. Thereby ROS level was decreased by CM in old HEF cells. These results suggest that CM extract has an antioxidant activity through FOXO activation.

• Journal of Applied Biological Chemistry
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• v.54 no.3
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• pp.225-229
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• 2011

This research was carried out to elucidate the impacts of dissolved oxygen (DO) concentration to phosphorus release mechanism from soil into water in lakes. $PO_4-P$ contributed to the growth of the total phosphorus (T-P). $PO_4-P$ was steadily increasing because water was accumulating $PO_4-P$. T-P was closely related to turbidity, pH, and DO. We found that DO had decreased because DO was consumed in organic matter decomposition, and that the resulting anaerobic decomposition occurred whenever water had run out of DO. We also found that pH had decreased sharply by production of organic acid by the anaerobic decomposition and that T-P decreased because a decrease in pH removed turbidity by precipitation. T-P was dissolved without microbial decomposition. This mechanism was of great importance in lakes because phosphorus is released from soil into water.

• Applied Biological Chemistry
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• v.44 no.1
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• pp.1-6
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• 2001

To elucidate the apoptosis mechanism of Trichoplusia ni cell, fundamental studies for apoptosis induction and suppression were performed. Hygromycin B, a known inducer of apoptosis, started the inhibition of T. ni cell growth at $200\;{\mu}/ml$ concentration. Furthermore, at $400\;{\mu}/ml$ concentration, DNA fragmentation was detected on day 2 of incubation. Although both dexamethasone and sodium butyrate inhibited T. ni cell growth, DNA fragmentation was not detected by both treatments. Also, when apoptosis induced T. ni cells with $200\;{\mu}/ml$ hygromycin B were treated with caspase inhibitor (Ac-DEVD-CHO), the apoptotsis was suppressed by 36%. In addition, N-acetylcysteine, another apoptosis repressor, also inhibited the apoptosis of T. ni cells. In order to express the anti-apoptosis gene (bcl-2), T. ni cells were transiently transformed with bcl-2 and its expression was confirmed by western blot analysis. These results showed the potential of developing new insect cell lines with suppressed apoptosis.

• Journal of KIISE:Software and Applications
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• v.32 no.6
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• pp.461-472
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• 2005

In this paper, we design and implement a graphical bio-ontology management system based on OWL(Web Ontology Language). It allows domain experts to easily manage sophisticated bio-ontologies in which biological knowledge is encoded. The knowledge can be seamlessly modeled into the ontology by well defined graphical notations, which capture most of subtle semantics inherently existing between biological terms. Our system provides a new construction mechanism, which can determine a considerable part of relationships between terms by their inheritance and inverse-inheritance. For keeping their semantics to be consistent, the mechanism supplies domain experts with information available from relationships being constructed or already constructed. The constructed ontology is basically formatted by OWL, which may benefit from its powerful semantic expressiveness. Additionally, it can be automatically translated into other standard languages without semantic loss, such as RDF/RDFS, DAML+OIL and so on. The main characteristics of our system is that it enables domain experts to delicately model the bio-ontology by the visualized construction mechanisms adopting well-defined graphical notations based on OWL.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.5
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• pp.411-416
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• 2002

Recently, the trial and success of malicious cyber attacks has been increased rapidly with spreading of Internet and the activation of a internet shopping mall and the supply of an online internet, so it is expected to make a problem more and more. Currently, the general security system based on Internet couldn't cope with the attack properly, if ever, other regular systems have depended on common softwares to cope with the attack. In this paper, we propose the positive selection mechanism and negative selection mechanism of T-cell, which is the biological distributed autonomous system, to develop the self/non-self recognition algorithm, the anomalous behavior detection algorithm, and AIS (Artificial Immune System) that is easy to be concrete on the artificial system. The proposed algorithm can cope with new intrusion as well as existing one to intrusion detection system in the network environment.