• 한국발생생물학회지:발생과생식
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• 제19권4호
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• pp.167-180
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• 2015

Arsenic is a toxic metalloid that exists ubiquitously in the environment, and affects global health problems due to its carcinogenicity. In most populations, the main source of arsenic exposure is the drinking water. In drinking water, chronic exposure to arsenic is associated with increased risks of various cancers including those of skin, lung, bladder, and liver, as well as numerous other non-cancer diseases including gastrointestinal and cardiovascular diseases, diabetes, and neurologic and cognitive problems. Recent emerging evidences suggest that arsenic exposure affects the reproductive and developmental toxicity. Prenatal exposure to inorganic arsenic causes adverse pregnancy outcomes and children's health problems. Some epidemiological studies have reported that arsenic exposure induces premature delivery, spontaneous abortion, and stillbirth. In animal studies, inorganic arsenic also causes fetal malformation, growth retardation, and fetal death. These toxic effects depend on dose, route and gestation periods of arsenic exposure. In males, inorganic arsenic causes reproductive dysfunctions including reductions of the testis weights, accessory sex organs weights, and epididymal sperm counts. In addition, inorganic arsenic exposure also induces alterations of spermatogenesis, reductions of testosterone and gonadotrophins, and disruptions of steroidogenesis. However, the reproductive and developmental problems following arsenic exposure are poorly understood, and the molecular mechanism of arsenic-induced reproductive toxicity remains unclear. Thus, we further investigated several possible mechanisms underlying arsenic-induced reproductive toxicity.

• 약학회지
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• 제46권3호
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• pp.185-191
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• 2002

Alzheimer's disease (AD) involves neuronal degeneration with impaired cholinergic transmission, particularly in areas of the brain associated with learning and memory. Several cholinesterase inhibitors are widely prescribed to ameliorate the cognitive deficits in AD patients. In an attempt to examine if tacrine and donepezil, two well-known cholinesterase inhibitors, exhibit additional pharmacological actions in primary cultured rat cortical cells, we investigated the effects on neuronal injuries induced by glutamate or N-methyl-D-aspartate (NMDA), $\beta$-amyloid fragment ( $A_{{beta}25-35)}$), and various oxidative insults. Both tacrine and donepezil did not significantly inhibit the excitotoxic neuronal damage induced by glutamate. However, tacrine inhibited the toxicity induced by NMDA in a concentration-dependent fashion. In addition, tacrine significantly inhibited the $A_{{beta}25-35)}$-induced neuronal injury at the concentration of 50 $\mu$M. In contrast, donepezil did not reduce the NMDA- nor $A_{{beta}25-35)}$-induced neuronal injury. Tacrine and donepezil had no effects on oxidative neuronal injuries in cultures nor on lipid peroxidation in vitro. These results suggest that, in addition to its anticholinesterase activity, the neuroprotective effects by tacrine against the NMDA- and $A_{{beta}25-35)$-induced toxicity may be beneficial for the treatment of AD. In contrast, the potent and selective inhibition of central acetylcholinesterase appears to be the major action mechanism of donepezil.

• Environmental Analysis Health and Toxicology
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• 제27권
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• pp.7.1-7.7
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• 2012

Objectives: Modafinil is a waking drug prescribed to narcolepsy patients, but its usage among healthy individuals is increasing to enhance their alertness or to mitigate fatigue. This study was conducted to investigate practical use and toxic effects on neuro-immune interaction of modafinil. Methods: This study reviewed the significance of psychoactive drugs, and discussed the benefits and risks of the application of modafinil, which seems to be ideal as an anti-psychotic or anti-fatigue agent. Results: Modafinil is known to have less or no adverse effects than those found in traditional psychostimulants such as amphetamine, methylphenidate or cocaine. It can be applied as an anti-psychotic or anti-fatigue agent. However, the waking mechanism of modafinil is yet to be fully revealed. Recent studies reported that modafinil may be subject to abuse and addiction. In addition prolonged sleeplessness induces stress responses and impairs immune function. Conclusions: Modafinil can be used by anyone, who wishes to work late, stay awake, enhance their cognitive reactions, or brighten their moods. Users may already be under a great level of stress, i.e. cancer patients or soldiers in a battle field. A psychoneuroimmunological approach is thus needed to investigate the multi-functional effects of modafinil.

• The Korean Journal of Physiology and Pharmacology
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• 제22권3호
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• pp.343-348
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• 2018

Recent human genetic studies have shown that $G{\beta}5$ is related to various clinical symptoms, such as sinus bradycardia, cognitive disability, and attention deficit hyperactivity disorder. Although the calcium signaling cascade is closely associated with a heterotrimeric G-protein, the function of $G{\beta}5$ in calcium signaling and its relevance to clinical symptoms remain unknown. In this study, we investigated the in vitro changes of store-operated calcium entry (SOCE) with exogenous expression of $G{\beta}5$. The cells expressing $G{\beta}5$ had enhanced SOCE after depletion of calcium ion inside the endoplasmic reticulum. $G{\beta}5$ also augmented Stim1- and Orai1-dependent SOCE. An ORAI1 loss-of-function mutant did not show inhibition of $G{\beta}5$-induced SOCE, and a STIM1-ERM truncation mutant showed no enhancement of SOCE. These results suggested a novel role of GNB5 and Stim1, and provided insight into the regulatory mechanism of SOCE.

• Molecules and Cells
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• 제23권3호
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• pp.259-271
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• 2007

Investigation of molecular and cellular mechanisms of synaptic plasticity is the major focus of many neuroscientists. There are two major reasons for searching new genes and molecules contributing to central plasticity: first, it provides basic neural mechanism for learning and memory, a key function of the brain; second, it provides new targets for treating brain-related disease. Long-term potentiation (LTP), mostly intensely studies in the hippocampus and amygdala, is proposed to be a cellular model for learning and memory. Although it remains difficult to understand the roles of LTP in hippocampus-related memory, a role of LTP in fear, a simplified form of memory, has been established. Here, I will review recent cellular studies of LTP in the anterior cingulate cortex (ACC) and then compare studies in vivo and in vitro LTP by genetic/pharmacological approaches. I propose that ACC LTP may serve as a cellular model for studying central sensitization that related to chronic pain, as well as pain-related cognitive emotional disorders. Understanding signaling pathways related to ACC LTP may help us to identify novel drug target for various mental disorders.

• 생물정신의학
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• 제25권4호
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• pp.89-100
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• 2018

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that delivers 1-2 mA of current to the scalp. Several clinical studies have been conducted to confirm the therapeutic effect of major depressive disorder (MDD) patients with tDCS. Some studies have shown tDCS's antidepressant effect, while the others showed conflicting results in antidepressant effects. Our aim of this review is to understand the biological bases of tDCS's antidepressant effect and review the results of studies on tDCS's antidepressant effect. For the review and search process of MDD treatment using tDCS, the US National Library of Medicine search engine PubMed was used. In this review, we discuss the biological mechanism of tDCS's antidepressant effect and the existing published literature including meta-analysis, systematic review, control trial, open studies, and case reports of antidepressant effects and cognitive function improvement in patients with MDD are reviewed. We also discuss the appropriate tDCS protocol for MDD patients, factors predictive of response to tDCS treatment, the disadvantages of tDCS in MDD treatment, and side effects.

• 턱관절균형의학회지
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• 제8권1호
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• pp.11-15
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• 2018

Recently, clinical efficacies of the intraoral balancing appliance therapy have been reported by several researchers, and it has been found that there are various kinds of diseases that can be effectively applied. However, studies on cerebrovascular disease, one of the main diseases with a high mortality rate, are still poorly reported, and studies of temporomandibular joint disorder (TMD)-induced changes in brain function suggest that cerebrovascular disease is more appropriate as an adaptive disorder of the temporomandibular joint (TMJ) balancing device. In the developed countries, the importance of research on the structure and function of the brain has been recognized and spurred on the related research. In Korea, the research on brain function and cognitive disorders should have promoted more massively. In order to regain its former reputation in the Korean medicine in the field of cerebrovascular disease, it should be spurred on basic research and clinical case studies. In addition, extensive and in-depth studies including animal studies are needed to establish the basis of underlying mechanisms of the TMJ balancing therapies.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제32권3호
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• pp.85-92
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• 2021

Attention-deficit/hyperactivity disorder (ADHD) leads to functional decline in academic performance, interpersonal relationships, and development in school-aged children. Early diagnosis and appropriate intervention can significantly reduce the functional decline caused by ADHD. Currently, there is no established biological marker for ADHD. Some studies have suggested that various indicators from the quantitative electroencephalogram (QEEG) may be useful biological markers for the diagnosis of ADHD. Until the 2010s, theta/beta ratio (TBR) was a biomarker candidate for ADHD that consistently showed high diagnostic value. However, limitations of TBR have recently been reported. Studies have demonstrated that phase-amplitude coupling, especially theta phase-gamma amplitude coupling, are related to cognitive dysfunction and may assist in the diagnosis of ADHD. As yet, the underlying mechanism is not clearly established, and the clinical efficacy of these biomarkers needs to be proven through well-controlled studies. Based on the heterogeneous characteristics of ADHD, subgrouping through QEEG plays a key role in diagnosis and treatment planning. Sophisticated, well-designed studies and meta-analyses are necessary to confirm these findings.

• Asia Marketing Journal
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• 제18권2호
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• pp.1-23
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• 2016

People receive support from others to solve problems that are difficult to solve on their own. During service encounters, customers also receive help from other customers. Inter-customer helping is a type of Customer Citizenship Behavior (CCB), which has become more prevalent with increased use of self-service technologies (SSTs). However, not all helps are created equal. The current research investigates the effects of the two types of help, autonomy- and dependency-oriented help during service encounters. Autonomy-oriented help refers to a partial hint to the problem, whereas dependency-oriented help refers to the full solution to the problem. Through experimental studies, we provide evidence that depending on the types of help received during service encounters, customers show different levels of satisfaction toward the firm. The results from Studies 1A and 1B show that autonomy- (vs. dependency-) oriented help leads to higher customer satisfaction. In addition, the current research demonstrates the mechanism for such effect. The results from Study 2 show that the relationship between the types of help and customer satisfaction is mediated by instrumentality and anxiety, which represent cognitive and affective paths respectively.

• Educational Technology International
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• 제19권2호
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• pp.199-228
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• 2018

The main purposes of this study were (a) to analyze the research trend of educational use of tangible technology, (b) to identify tangible learning mechanisms, and potential benefits of learning with tangible technology, and (c) to provide references and future research directions. We conducted a systematic literature review to search for academic papers published in recent five years (from 2013 to 2017) in the major databases. Forty papers were coded and analyzed by the established coding framework in four dimensions: (a) basic publication information, (b) learning context, (c) learning mechanism, and (d) learning benefits. Overall, the results show that tangible technology has been used more for young learners in the kindergarten and primary school contexts mainly for science learning, to achieve both cognitive and affective learning outcomes, by coupling tangible objects with tabletops and desktop computers. From the synthesis of the review findings, this study suggests that the affordances of tangible technology useful for learning include embodied interaction, physical manipulations, and the physical-digital representational mapping. With such technical affordances, tangible technologies have the great potential in three particular areas in education: (a) learning spatial relationships, (b) making the invisible visible, and (c) reinforcing abstract concepts through the correspondence of representations. In conclusion, we suggest some areas for future research endeavors.