• Journal of Chest Surgery
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• v.16 no.2
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• pp.199-212
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• 1983

The inhibition/influences of adenine compounds on the heart have been described repeatedly by many investigators, since the first report by Druny and Szent-Gyorgyi [1929]. These studies have shown that adenosine and adenine nucleotides have an over-all effect similar to that of acetylcholine [ACh] by slowing and weakening the heartbeat. The basic cellular and membrane events underlying the inhibitory action of adenosine on sinus rate, however, are not well understood. Furthermore, the physiological role of adenosine in regulation of the heartbeat remains still to be elucidated. Therefore, this study was undertaken in order to examine the response of rabbit SA node to adenosine and to compare the response to that of ACh. Isolated SA node preparation, whole atrial pair, or left atrlal strip was used in each experiment. Action potentials of SA node were recorded through the intracellular glass microelectrodes, which were filled with 3M KCI and had resistance of 30-50 M. All experiments were performed in a bicarbonate-buffered Tyrode solution which was aerated with 3% $CO_2-97%$ $O_2$ gas mixture and kept at $35^{\circ}C$. Spontaneous firing rate of SA node at 35C [Mean + SEM, n=16] was 154 + 3.3 beats/min. The parameters of action potentials were: maximum astolic potential [MDP], -731.7mV: overshoot [OS], 9 + 1.4mV; slope of pacemaker potential [SPP], 94 3.0mV/sec.Adenosine suppressed the firing rate of SA node in a dose dependent manner. This inhibitory effect appeared at the concentration of $10^{-6}M$ and was potentiated in parallel with the increase in adenosine concentration. Changes in action potential by adenosine were dose-dependent increase of MDP and decrease of SPP until $10^{-4}$. Above this concentration, however, the amplitude of action potential decreased markedly due to the simultaneous decrease of both MDP and OS. All these effects of adenosine were not affected by pretreatment of atropine [2mg/l] and propranolol [$5{\times}10^{-6}M$]. ACh [$10^{-6}M$] responses on action potential were similar to those of adenosine by increasing MDP and decreasing SPP. These effects of ACh disappeared by pretreatment of atropine [2mg/1]. Inhibition/effects of adenosine and ACh on sinus rate were enhanced synergistically with the simultaneous administration of adenosine and ACh. Marked decrease of overshoot potential was the most prominent feature on action potential. Dipyridamole [DPM], which is known to block the adenosine transport across cell membrane, definitely potentiated the action of adenosine . Adenosine suppressed the sinus rate and atrial contractility in the same dosage range, even in the reserpinized preparation. Above` results suggest that adenosine suppresses pacemaker activity, like ACh, by acting directly on the membrane of SA node, increasing MDP and decreasing SPP.

• Molecular & Cellular Toxicology
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• v.3 no.2
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• pp.98-106
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• 2007

Genotoxic stress triggers a variety of biological responses including the transcriptional activation of genes regulating DNA repair, cell survival and cell death. In this study, we investigated to examine gene expression profiles and genotoxic response in TK6 cells treated with DNA damaging agents MNNG (N-methyl-N'-nitrosoguanidine) and hydrogen peroxide $(H_2O_2)$. We extracted total RNA in three independent experiments and hybridized cRNA probes with oligo DNA chip (Applied Biosystems Human Genome Survey Microarray). We analyzed raw signal data with R program and AVADIS software and identified a number of deregulated genes with more than 1.5 log-scale fold change and statistical significancy. We indentified 14 genes including G protein alpha 12 showing deregulation by MNNG. The deregulated genes by MNNG represent the biological pathway regarding MAP kinase signaling pathway. Hydrogen peroxide altered 188 genes including sulfiredoxins. These results show that MNNG and $H_2O_2$ have both uniquely regulated genes that provide the potential to serve as biomarkers of exposure to DNA damaging agents.

• Archives of Pharmacal Research
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• v.22 no.5
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• pp.437-447
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• 1999

Type I diabetes, also known as insulin-dependent diabetes mellitus (IDDM) results from the destruction of insulin-producing pancreatic $\beta$ cells by a progressive $\beta$ cell-specific autoimmune process. The pathogenesis of autoimmune IDDM has been extensively studied for the past two decades using animal models such as the non-obese diabetic (NOD) mouse and the Bio-Breeding (BB) rat. However, the initial events that trigger the immune responses leading to the selective destruction of the $\beta$ cells are poorly understood. It is thought that $\beta$ cell auto-antigens are involved in the triggering of $\beta$ cell-specific autoimmunity. Among a dozen putative $\beta$ cell autoantigens, glutamic acid decarboxylase (GAD) has bee proposed as perhaps the strongest candidate in both humans and the NOD mouse. In the NOD mouse, GAD, as compared with other $\beta$ cell autoantigens, provokes the earliest T cell proliferative response. The suppression of GAD expression in the $\beta$ cells results in the prevention of autoimmune diabetes in NOD mice. In addition, the major populations of cells infiltrating the iselts during the early stage of insulitis in BB rats and NOD mice are macrophages and dendritic cells. The inactivation of macrophages in NOD mice results in the prevention of T cell mediated autoimmune diabetes. Macrophages are primary contributors to the creation of the immune environment conducive to the development and activation of $\beta$cell-specific Th1-type CD4+ T cells and CD8+ cytotoxic T cells that cause autoimmune diabetes in NOD mice. CD4+ and CD8+ T cells are both believed to be important for the destruction of $\beta$ cells. These cells, as final effectors, can kill the insulin-producing $\beta$ cells by the induction of apoptosis. In addition, CD8+ cytotoxic T cells release granzyme and cytolysin (perforin), which are also toxic to $\beta$ cells. In this way, macrophages, CD4+ T cells and CD8+ T cells act synergistically to kill the $\beta$ cells in conjunction with $\beta$ cell autoantigens and MHC class I and II antigens, resulting in the onset of autoimmune type I diabetes.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.111-121
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• 2010

Differential tolerance to protoporphyrinogen oxidase (Protox)-inhibiting herbicides, oxyfluorfen was observed between leaf ages in squash. Physiological responses to oxyfluorfen, including leaf injury, cellular leakage, accumulation of tetrapyrroles, and antioxidative enzymes activity, were investigated in leaf age classes of squash to identify mechanisms of oxyfluorfen tolerance. Leaf 1, 2, and 3 injuries for Joongangaehobak were >10,000, 1,286, and 1.6-fold higher than that of leaf 4, after treatment of oxyfluorfen. On the other hand, leaf 1, 2, and 3 injuries for Sintowjahobak were 725, 366, and >0.6-fold higher than that of leaf 4, after treatment of oxyfluorfen. However, in contrast to oxyfluorfen treatment results, leaf injury of squash leaf 4 treated with paraquat was much smaller than in leaves 1, 2 and 3. Electrolyte leakage from the tissues treated with oxyfluorfen was higher in the youngest leaf (Leaf 4) than in the older leaves 1, 2, and 3. Differential leaf response to oxyfluorfen of squash appears to be due in large part to differences in protoporphyrin IX (Proto IX), Mg-Proto IX, and Mg-Proto IX monomethyl ester accumulation in treated leaves. In contrast, leaf 4 had higher activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase than leaf 1 after treatment with oxyfluorfen. However, the induction in antioxidant activity in leaf 4 was not enough to overcome the toxic effects of a Protox inhibitor, oxyfluorfen, so the leaf eventually died.

• Journal of Life Science
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• v.26 no.10
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• pp.1137-1152
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• 2016

Cells sense, respond, and adapt to a low oxygen environment called hypoxia, which is widely involved in a variety of human diseases. Adaptation to low oxygen concentrations includes gene expression changes by inducing hypoxic genes and reducing aerobic genes. Recently, the mitochondrial respiratory chain has been implicated in the control of these oxygen-regulated genes when cells experience hypoxia. In order to obtain an insight into an effect of the mitochondrial respiratory chain on cellular response to hyxpoxia, we here examined whole genome transcript signatures of respiration-proficient and respiration-deficient budding yeasts exposed to hypoxia using DNA microarrays. By comparing whole transcriptomes to hypoxia in respiration-proficient and respiration-deficient yeasts, we found that there are several classes of oxygen-regulated genes. Some of them require the mitochondrial respiratory chain for their expression under hypoxia while others do not. We found that the majority of hypoxic genes and aerobic genes need the mitochondrial respiratory chain for their expression under hypoxia. However, we also found that there are some hypoxic and aerobic genes whose expression under hypoxia is independent of the mitochondrial respiratory chain. These results indicate a key involvement of the mitochondrial respiratory chain in oxygen-regulated gene expression and multiple mechanisms for controlling oxygen-regulated gene expression. In addition, we provided gene ontology analyses and computational promoter analyses for hypoxic genes identified in the study. Together with differentially regulated genes under hypoxia, these post-analysis data will be useful resources for understanding the biology of response to hypoxia.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.54-54
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• 2003

Prostate gland contains neuroendocrine cells (PNECs) are playing important roles in physiological and pathophysiological processes of the prostate gland. Here, we investigated the role of purinoceptors in PNECs freshly isolated from rat ventral prostate (RPNECs) that show immunoreactivity to chromogranin A. Fura-2 ratiometry revealed that ATP evokes both fast Ca$\^$2+/ influx and store Ca$\^$2+/ release in RPNECs. A whole-cell patch clamp study demonstrated fast inactivating cationic current activated by ATP or by ${\alpha}$,${\beta}$-MeATP, which was blocked by ATP-TNP. The activation of P2X inward current was tightly associated with a sharp increase in [Ca$\^$2+/]$\sub$c/. The presence of P2X1/3 subtypes were proved by RT-PCR analysis. For the stored Ca$\^$2+/ release, ATP and UTP showed similar effects, suggesting the dominant role or P2Y2 subtypes, also confirmed by RT-PCR. Both P2X (${\alpha}$,${\beta}$-MeATP) and P2Y (UTP) stimulation induced changes in the cell morphology (initial shrinkage and blob formation on the surface) reversibly. Exocytotic membrane trafficking events were monitored with the membrane-bound fluorescent dye, FM1-43 using confocal microscopy. In spite of the similar Ca$\^$2+/ responses, UTP was far less effective in triggering exocytosis than ${\alpha}$,${\beta}$ -MeATP. Since serotonin is reportedly stored in the secretory granule of PNECs, we directly examined whether the aforementioned agonists elicit release of serotonin using carbon fiber electrode-amperometry. In accordance with the results of FM1 -43 experiments, ${\alpha}$,${\beta}$-MeATP efficiently evoke serotonin secretion while not with UTP. In summary, the P2X-mediated Ca$\^$2+/ influx plays crucial roles in the exocytosis of RPNECs. Although a global increase in [Ca$\^$2+]$\sub$c/ might be related with the morphological changes, a sharp rise of [Ca$\^$2+/]$\sub$c/ in the putative sub-plasmalemmal ‘microdomains’ might be a decisive factor for the exocytosis.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.53-59
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• 2002

Background: Clinical observations and laboratory studies have supported an immune basis for most acquired aplastic anemias, with the majority of patients responding to immunosuppressive therapy. Fas, a member of the tumor necrosis factor (TNF) receptor superfamily is a critical downregulator of cellular immune responses. Proinflammatory cytokines like interferon gamma (IFN-${\gamma}$) and TNF-${\alpha}$ can induce Fas expression and render hematopoietic progenitor cells susceptible to Fas-induced growth suppression and apoptosis. Methods: In order to investigate the involvement of apoptosis in the pathogenesis of aplastic anemia (AA), we measured the expression of Fas antigen and caspase-3 on bone marrow (BM) mononuclear cells (MNCs) of AA in the presence or absence of IFN-${\gamma}$, TNF-${\alpha}$, or macrophage inflammatory protein 1-${\alpha}$ (MIP-$1{\alpha}$). Results: We confirmed that AA BM MNCs were more apoptotic and highly expressed Fas antigen than normal donors. Stimulation by IFN-${\gamma}$, TNF-${\alpha}$, or MIP-$1{\alpha}$ increased Fas antigen and caspase-3 expression in AA BM MNCs than BM MNCs of normal donors. Anti-Fas monoclonal antibody enhanced IFN-${\gamma}$, TNF-${\alpha}$, or MIP$1{\alpha}$ mediated caspase-3 expression in BM MNCs of normal donors. Among these three cytokines, IFN-${\gamma}$ enhanced apoptosis most strongly via Fas-caspase-3 pathway. Conclusion: These results suggest that Fas signal pathway may play a role in the pathophysiology of aplastic anemia and negative hematopoietic regulators like IFN-${\gamma}$ can induce apoptosis of bone marrow progenitors in part by Fas induction.

• Korean Journal of Veterinary Research
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• v.45 no.1
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• pp.45-53
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• 2005

GroE that is a heat shock protein composed of GroEL and GroES is known as an immunodominant target of both the humoral and cellular immune responses in bovine brucellosis. This study was carried out to characterize groE gene encoding heat shock proteins of B. abortus isolated in Korea and to evaluate the immunogenicity of the GroE protein expressed in E. coli system. In PCR the specific signals with the size of 2,077 bp were detected in five strains isolated from the mammary lymphnodes of the dairy cattle that were serologically positive and the reference strains. In comparison of the sequences of nucleotides and amino acids among the strains, GroES showed 100% identity in both sequences. GroEL was evaluated 99.0~99.9% in nucleotides and 98.0~100% homology in amino acids. The groE gene including groES and groEL was inserted into pET29a vector and constructed pET29a-GroE recombinant plasmids. The inserted groE was confirmed by digestion with Nco1 and EcoR1 endonucleases and nucleotide sequencing. E. coli BL (DE3) was transformed with pET29a-GroE, named as E. coli BL (DE3)/pET29a-GroE. In SDS-PAGE, it was evident that the recombinant plasmid effectively expressed the polypeptides for GroES (10 kDa) and GroEL (60 kDa) in 0.5, 1 and 2 hours after IPTG induction. The immuno-reactivity of the expressed proteins were proved in mouse inoculation and Western blot analysis.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.349-356
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• 2012

Eicosanoid mediates various cellular immune responses in insects. This study aimed to discover its novel action on the modulation of hemocyte populations in response to an immune challenge. Upon bacterial challenge, the last instar larvae of the beet armyworm, Spodoptera exigua, increased their total hemocyte density in 2 h, and then decreased it to a basal hemocyte density level. This rapid increase in total hemocyte density was explained by an increase of plasmatocyte and spherulocyte densities. When larvae were treated with dexamethasone (a specific phospholipase $A_2$ ($PLA_2$) inhibitor), they did not show any increase in hemocyte density in response to bacterial challenge. However, the addition of arachidonic acid (a catalytic product of $PLA_2$) to larvae treated with dexamethasone recovered the up-regulation of hemocyte density in response to bacterial infection. Among eicosanoid, cyclooxygenase (COX), but not lipoxygenase (LOX), products seemed to mediate the increase of hemocyte density in response to bacterial infection because naproxene (a COX inhibitor) inhibited the hemocyte density increase, though esculetin (a LOX inhibitor) did not. Prostaglandin $E_2$, a COX product, significantly increased the hemocyte density even without bacterial infection. These results suggest that eicosaniod mediates a rapid increase in total hemocyte density in response to immune challenge.

• Molecules and Cells
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• v.41 no.5
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• pp.454-464
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• 2018

Crosstalk between G-protein signaling and glutamatergic transmission within the brain reward circuits is critical for long-term emotional effects (depression and anxiety), cravings, and negative withdrawal symptoms associated with opioid addiction. A previous study showed that Regulator of G-protein signaling 4 (RGS4) may be implicated in opiate action in the nucleus accumbens (NAc). However, the mechanism of the NAc-specific RGS4 actions that induce the behavioral responses to opiates remains largely unknown. The present study used a short hairpin RNA (shRNA)-mediated knock-down of RGS4 in the NAc of the mouse brain to investigate the relationship between the activation of ionotropic glutamate receptors and RGS4 in the NAc during morphine reward. Additionally, the shRNA-mediated RGS4 knock-down was implemented in NAc/striatal primary-cultured neurons to investigate the role that striatal neurons have in the morphine-induced activation of ionotropic glutamate receptors. The results of this study show that the NAc-specific knock-down of RGS4 significantly increased the behaviors associated with morphine and did so by phosphorylation of the GluR1 (Ser831) and NR2A (Tyr1325) glutamate receptors in the NAc. Furthermore, the knock-down of RGS4 enhanced the phosphorylation of the GluR1 and NR2A glutamate receptors in the primary NAc/striatal neurons during spontaneous morphine withdrawal. These findings show a novel molecular mechanism of RGS4 in glutamatergic transmission that underlies the negative symptoms associated with morphine administration.