• 아태비즈니스연구
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• 제11권2호
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• pp.119-132
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• 2020

Purpose - This study seeks to deepen our understanding of abusive supervision and its negative consequences on subordinates. Specifically, it examines the underlying psychological mechanism between abusive supervision and subordinates' work engagement, in particular with its focus on the mediational role of psychological contract breach. Design/methodology/approach - Following the two rounds of pilot interviews, this study collected and analyzed 182 survey data from one construction company and one hospital - the sectors in which abusive supervision is known to be frequent, with one-month interval to avoid common methods variances. Findings - We have two key findings. First, abusive supervision is negatively related to subordinates' work engagement. Second, the psychological contract violation mediates the relationship between abusive supervision and subordinates' work engagement. Research implications or Originality - This study enriches extant research on abusive supervision by deepening our understanding of the underlying mechanism in which abusive supervision causes negative outcomes. On a practical note, companies need further efforts to address abusive supervision, for example, by introducing sophisticated HR practices, including accessible grievance procedures and more serious disciplinary actions, and/or by offering leadership educations to supervisors.

• 대한화학회지
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• 제68권3호
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• pp.139-145
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• 2024

This study aims to elucidate the mechanism involved in the hydrolysis of the hexacyanoferrate(III) complex ion (Fe(CN)₆^3-) and the mechanism leading to the formation of Prussian blue (Fe^III₄[Fe_II(CN)₆]₃·xH₂O, PB) in acidic aqueous solutions at moderately elevated temperatures. Hydrolysis constitutes a crucial step in generating PB through the widely used single-source or precursor method. Recent PB syntheses predominantly rely on the single-source method, where hexacyanoferrate(II/III) is the exclusive reactant, as opposed to the co-precipitation method employing bare metal ions and hexacyanometalate ions. Despite the widespread adoption of the single-source method, mechanistic exploration remains largely unexplored and speculative. Utilizing UV-vis spectrophotometry, negative-ion mode liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and a devised reaction, this study identifies crucial intermediates, including aqueous Fe^2+/3+ ions and hydrocyanic acid (HCN) in the solution. These two intermediates eventually combine to form thermodynamically stable PB. The findings presented in this research significantly contribute to understanding the fundamental mechanism underlying the acid-catalyzed hydrolysis of the hexacyanoferrate(III) complex ion and the subsequent formation of PB, as proposed in the sequential mechanism introduced herein. This finding might contribute to the cost-effective synthesis of PB by incorporating diverse metal ions and potassium cyanide.

• 정신신체의학
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• 제4권2호
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• pp.262-268
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• 1996

신체화를 이해하는데 신체화를 형성하게 된 행동이면의 정신적인 갈등배경을 이해하는 것이 중요하다. 그러나 신체화의 생물학적 과정을 파악하고 증상의 유지요인과 악화요소를 알아보아 변화되어 가는 형성과정을 이해하는 점이 더욱 중요하다. 그리고 문화-사회적 특성에 따라 신체증상호소의 방법이나 내용이 다르다는 점을 염두에 두어야 한다. 신체화를 이해하는 데에는 심리적, 생물학적, 사회, 인종, 역사적인 요소가 모두 함께 영향을 미치므로 통합적인 관점에서 파악해 나가지 않으면 안된다.

• The Korean Journal of Physiology and Pharmacology
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• 제17권1호
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• pp.31-36
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• 2013

The present study was undertaken to investigate the influence of eupatilin on vascular smooth muscle contractility and to determine the mechanism involved. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Eupatilin more significantly relaxed fluoride-induced vascular contraction than thromboxane $A_2$ or phorbol ester-induced contraction suggesting as a possible anti-hypertensive on the agonist-induced vascular contraction regardless of endothelial nitric oxide synthesis. Furthermore, eupatilin significantly inhibited fluoride-induced increases in pMYPT1 levels. On the other hand, it didn't significantly inhibit phorbol ester-induced increases in pERK1/2 levels suggesting the mechanism involving the primarily inhibition of Rho-kinase activity and the subsequent phosphorylation of MYPT1. This study provides evidence regarding the mechanism underlying the relaxation effect of eupatilin on agonist-induced vascular contraction regardless of endothelial function.

• Journal of Ship and Ocean Technology
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• 제8권2호
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• pp.29-40
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• 2004

Interaction of grounded ice ridges with underlying seabed is one of the major considerations in the design of Arctic pipeline system. Previously several ice scour models were developed by researchers to describe the ice scour-seabed interaction mechanism. In this paper, a parametric study on ice scouring mechanism is performed and the limitation of ice scour-seabed interaction models is discussed. Simple laboratory tests are carried out and then the shape pattern of deposited soil around the ice is redefined. New ice scour model assumes trapezoidal cross section based on the field observation data. Ice scour depth and soil resistance forces on seabed are calculated with varying the keel angle of a model ice ridge.

• 생약학회지
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• 제49권4호
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• pp.285-290
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• 2018

Harmine, a beta-carboline alkaloid isolated from the seeds of Peganum harmala has been reported as a promising drug candidate for cancer therapy. However, the effect of harmine on breast cancer remains still unclear. In this study, the effect of harmine on the cell proliferation, migration, and invasion of breast cancer MDA-MB231 cells and the underlying mechanism were investigated. The results indicated that harmine inhibited the proliferation MDA-MB231 cells in a dose-dependent manner and markedly suppressed migration and invasion of MDA-MB231 cells. The mechanism involved in part through Notch signaling. The Notch activity was significantly inhibited by harmine treatment and harmine suppressed the expression of Jagged1 which is a key ligand to activate Notch signaling. These findings suggest a novel mechanism of harmine on anti-cancer activity and harmine may act as a potential therapeutic drug for breast cancer treatment.

• IMMUNE NETWORK
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• 제7권1호
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• pp.18-25
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• 2007

Background: Although glucocorticoids (GCs) are effective in controlling asthma in the majority of patients, a subset of asthmatics fails to demonstrate a satisfactory response, even to systemic GC therapy. This population is referred to as being "steroid-resistant". The actual mechanism underlying steroid resistance in asthma remains to be elucidated. Methods: We have investigated how dexamethasone (DEX) regulates asthmatic phenotypes in a murine model of asthma, in which mice received i.p. immunization twice, followed by two bronchoprovocations with aerosolized OVA with a one-week interval, which we have recently described. Results: Pretreatment with DEX resulted in an inhibition of NF-${\kappa}B$ activation in asthmatic lungs, and also inhibited bronchoalveolar lavage (BAL) levels of NF-${\kappa}B$-dependent cytokines such as TNF-${\alpha}$ and CC chemokines [eotaxin and monocyte chemotactic protein (MCP)-1]. DEX was effective in suppressing airway hyperresponsiveness (AHR) at 10 h, Th2-dependent asthmatic phenotypes such as airway eosinophilia, BAL levels of Th2 cytokines (IL-5 and IL-13), and mucin production. However, DEX failed to suppress BAL levels of CXC chemokines [macrophage inflammatory protein-2 (MIP-2) and keratinocyte-derived chemokine (KC)] and airway neutrophilia. Conclusion: Airway neutrophilia is among the phenomena observed in patients with severe GC-resistant asthma. This study will provide insight into the molecular basis for airway neutrophila seen in steroid-resistant asthma. Further studies are required to delineate the underlying mechanism of CXC chemokine expression in asthma.

• Biomolecules & Therapeutics
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• 제20권6호
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• pp.532-537
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• 2012

Avicularin, quercetin-3-${\alpha}$-L-arabinofuranoside, has been reported to possess diverse pharmacological properties such as anti-inflammatory and anti-infectious effects. However, the underlying mechanism by which avicularin exerts its anti-inflammatory activity has not been clearly demonstrated. This study aimed to elucidate the anti-inflammatory mechanism of avicularin in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. Avicularin significantly inhibited LPS-induced excessive production of pro-inflammatory mediators such as nitric oxide (NO) and $PGE_2$ and the protein levels of iNOS and COX-2, which are responsible for the production of NO and $PGE_2$, respectively. Avicularin also suppressed LPS-induced overproduction of pro-inflammatory cytokine IL-$1{\beta}$. Furthermore, avicularin significantly suppressed LPS-induced degradation of $I{\kappa}B$, which retains NF-${\kappa}B$ in the cytoplasm, consequently inhibiting the transcription of pro-inflammatory genes by NF-${\kappa}B$ in the nucleus. To understand the underlying signaling mechanism of anti-inflammatory activity of avicularin, involvement of multiple kinases was examined. Avicularin significantly attenuated LPS-induced activation of ERK signaling pathway in a concentration-dependent manner. Taken together, the present study clearly demonstrates that avicularin exhibits anti-inflammatory activity through the suppression of ERK signaling pathway in LPS-stimulated RAW 264.7 macrophage cells.

• Biomolecules & Therapeutics
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• 제22권3호
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• pp.200-206
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• 2014

N-(p-Coumaryol) tryptamine (CT), a phenolic amide, has been reported to exhibit anti-oxidant and anti-inflammatory activities. However, the underlying mechanism by which CT exerts its pharmacological properties has not been clearly demonstrated. The objective of this study is to elucidate the anti-inflammatory mechanism of CT in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells. CT significantly inhibited LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and $PGE_2$, and protein expressions of iNOS and COX-2. In addition, CT significantly suppressed LPS-induced secretion of pro-inflammatory cytokines such as TNF-${\alpha}$ and IL-$1{\beta}$. To elucidate the underlying anti-inflammatory mechanism of CT, involvement of MAPK and Akt signaling pathways was examined. CT significantly attenuated LPS-induced activation of JNK/c-Jun, but not ERK and p38, in a concentration-dependent manner. Interestingly, CT appeared to suppress LPS-induced Akt phosphorylation. However, JNK inhibition, but not Akt inhibition, resulted in the suppression of LPS-induced responses, suggesting that JNK/c-Jun signaling pathway significantly contributes to LPS-induced inflammatory responses and that LPS-induced Akt phosphorylation might be a compensatory response to a stress condition. Taken together, the present study clearly demonstrates CT exerts anti-inflammatory activity through the suppression of JNK/c-Jun signaling pathway in LPS-challenged RAW264.7 macrophage cells.

• Biomolecules & Therapeutics
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• 제21권3호
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• pp.216-221
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• 2013

Aromadendrin, a flavonol, has been reported to possess a variety of pharmacological activities such as anti-inflammatory, antioxidant, and anti-diabetic properties. However, the underlying mechanism by which aromadendrin exerts its biological activity has not been extensively demonstrated. The objective of this study is to elucidate the anti-inflammatory mechanism of aromadedrin in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. Aromadendrin significantly suppressed LPS-induced excessive production of pro-inflammatory mediators such as nitric oxide (NO) and $PGE_2$. In accordance, aromadendrin attenuated LPS-induced overexpression iNOS and COX-2. In addition, aromadendrin significantly suppressed LPS-induced degradation of $I{\kappa}B$, which sequesters NF-${\kappa}B$ in cytoplasm, consequently inhibiting the nuclear translocation of pro-inflammatory transcription factor NF-${\kappa}B$. To elucidate the underlying signaling mechanism of anti-inflammatory activity of aromadendrin, MAPK signaling pathway was examined. Aromadendrin significantly attenuated LPS-induced activation of JNK, but not ERK and p38, in a concentration-dependent manner. Taken together, the present study clearly demonstrates that aromadendrin exhibits anti-inflammatory activity through the suppression of nuclear translocation of NF-${\kappa}B$ and phosphorylation of JNK in LPS-stimulated RAW 264.7 macrophage cells.