• Clinical and Experimental Reproductive Medicine
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• v.41 no.3
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• pp.97-107
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• 2014

The placenta is a temporary fetomaternal organ capable of supporting fetal growth and development during pregnancy. In particular, abnormal development and dysfunction of the placenta due to cha nges in the proliferation, differentiation, cell death, and invasion of trophoblasts induce several gynecological diseases as well as abnormal fetal development. Autophagy is a catalytic process that maintains cellular structures by recycling building blocks derived from damaged microorganelles or proteins resulting from digestion in lysosomes. Additionally, autophagy is necessary to maintain homeostasis during cellular growth, development, and differentiation, and to protect cells from nutritional deficiencies or factors related to metabolism inhibition. Induced autophagy by various environmental factors has a dual role: it facilitates cellular survival in normal conditions, but the cascade of cellular death is accelerated by over-activated autophagy. Therefore, cellular death by autophagy has been known as programmed cell death type II. Autophagy causes or inhibits cellular death via the other mechanism, apoptosis, which is programmed cell death type I. Recently, it has been reported that autophagy increases in placenta-related obstetrical diseases such as preeclampsia and intrauterine growth retardation, although the mechanisms are still unclear. In particular, abnormal autophagic mechanisms prevent trophoblast invasion and inhibit trophoblast functions. Therefore, the objectives of this review are to examine the characteristics and functions of autophagy and to investigate the role of autophagy in the placenta and the trophoblast as a regulator of cell death.

• BMB Reports
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• v.34 no.1
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• pp.80-84
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• 2001

The human papillomavirus E7 protein can form a specific complex with a retinoblastoma tumor suppressor gene product (p105-Rb) that results in the release of the E2F transcription factor, which is critical for the growth-deregulation and transforming properties of the viral E7 oncoprotein. In an attempt to apply interaction between the E7 oncoprotein and a target cellular protein Rb for an in vitro screening system for drugs against human papillomavirus infection, we primarily investigated the E7Rb binding through a pull down assay and enzyme-linked immunosorbent assay. The pull down assay showed that both glutathione S-transferase-tagged E7 and His-tagged E7 immobilized on resins specifically produced complexes with bacterially expressed Rb in a dose-dependent manner, as determined by immunoblot analyses. This result coincided with that of an enzyme-linked immunosorbent assay, which is a useful system for the mass screening of potential drugs. Taken together, this screening system (based on the interaction between E7 and Rb) can be a promising system in the development of drugs against cervical cancers caused by human papillomavirus infection.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.825-830
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• 1999

The purpose of this study is to improve overall performance of prefoamed lightweight cellular concrete for On-Dol system floor. This study includes 4 sections as follows. \circled1 Analysis of the structural characteristics of On-Dol System focusing on the lightweight cellular concrete insulation layer. \circled2 Establishment of the mixing design equations. \circled3 Development of some admixtures used with foaming agent. \circled4 Improvement of the equipment for onsite production. This study has proven that, compared with the current existing one, the newly developed lightweight cellular concrete has been reduced the usage of cement by 20% and the cracks caused by cement drying shrinkage up to 80% but has shown the increased compression strength by 20% at 7 days curing period. The volume contraction of freshly prepared cellular concrete by the loss of foam was hardly found in newly developed lightweight cellular concrete.

• Molecules and Cells
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• v.47 no.1
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• pp.100006.1-100006.10
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• 2024

Nitric oxide (NO) serves as an evolutionarily conserved signaling molecule that plays an important role in a wide variety of cellular processes. Extensive studies in Drosophila melanogaster have revealed that NO signaling is required for development, physiology, and stress responses in many different types of cells. In neuronal cells, multiple NO signaling pathways appear to operate in different combinations to regulate learning and memory formation, synaptic transmission, selective synaptic connections, axon degeneration, and axon regrowth. During organ development, elevated NO signaling suppresses cell cycle progression, whereas downregulated NO leads to an increase in larval body size via modulation of hormone signaling. The most striking feature of the Drosophila NO synthase is that various stressors, such as neuropeptides, aberrant proteins, hypoxia, bacterial infection, and mechanical injury, can activate Drosophila NO synthase, initially regulating cellular physiology to enable cells to survive. However, under severe stress or pathophysiological conditions, high levels of NO promote regulated cell death and the development of neurodegenerative diseases. In this review, I highlight and discuss the current understanding of molecular mechanisms by which NO signaling regulates distinct cellular functions and behaviors.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.3
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• pp.111-118
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• 2006

This paper presents design and development of a simulator evaluates the performance of a hierarchical cellular system. The proposed hierarchical cellular simulator, consisting of macro, micro, and pico cells, applies the wrap-around technique to reduce simulation time. The simulator is implemented as object oriented class models by using the C++ language in a PC environment. The resulting application can evaluate the interference, SIR(Signal to Interference Ratio), and capacity of a hierarchical cellular system in various configurations. Moreover, it can be used in other applications such as power control, call admission control, hand over scheme.

• Journal of Families and Better Life
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• v.31 no.6
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• pp.83-96
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• 2013

The aim of this study was to identify the differences in cellular phone dependency and its use levels of usage purposes according to children's gender, and also to analyze the differences in individual and interpersonal relations development due to cellular phone dependency in children based on gender. Using the first year data of the Korean Child and Youth Panel Survey(KCYPS) 2010, this study analyzed 1,604 fourth graders who have their own cellular phones. For statistical analysis, descriptive statistics were calculated and mean difference analyses were conducted. The results showed that there was no difference between boys and girls in cellular phone dependency. The girls' total phone use level was higher than that of boys and meaningful gender differences in the phone use levels were found in the five phone usage purposes. In both boys and girls, the higher phone dependency groups demonstrated higher levels of phone use in more than eight usage purposes, lower self-resilience and self-regulating learning ability, and less positive peer and teacher relations. These findings show the importance of being concerned about and educating children in the fourth grade about the proper uses of cellular phones.

• Korean Journal of Child Studies
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• v.35 no.1
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• pp.119-133
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• 2014

The purpose of this study is to examine the effects of time perspective, self-control and cellular phone addiction on academic procrastination, and to cellular phone addiction has any mediating effects in relation to the effects of adolescents' time perspective and self-control on academic procrastination. For this study, a survey was conducted with total 651 students in middle and high schools. Those who omitted responses or answered in ways which were otherwise invalid were excluded and finally, questionnaires responded to by 558 students were analyzed. Employing SPSS Win 12.0, average value, standard deviation, frequency analysis, Pearson's correlation analysis, stepwise multiple regression analysis, and simple linear regression analysis were used for the purposes of statistical analysis. In conclusion, first, explanations were made in order of future-oriented time perspective which is subordinate domain of view of time perspective, self-control, and cellular phone addiction. Second, it was found that cellular phone addiction has partially mediating effect on the relationships between future-oriented time perspective which is a subordinate area of adolescents' time perspective, and academic procrastination. Third, it was found that cellular phone addiction has partially mediating effect on the relationships between adolescents' self-control and academic procrastination.

• BMB Reports
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• v.52 no.1
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• pp.35-41
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• 2019

Cellular senescence, a permanent state of cell cycle arrest, is believed to have originally evolved to limit the proliferation of old or damaged cells. However, it has been recently shown that cellular senescence is a physiological and pathological program contributing to embryogenesis, immune response, and wound repair, as well as aging and age-related diseases. Unlike replicative senescence associated with telomere attrition, premature senescence rapidly occurs in response to various intrinsic and extrinsic insults. Thus, cellular senescence has also been considered suppressive mechanism of tumorigenesis. Current studies have revealed that therapy-induced senescence (TIS), a type of senescence caused by traditional cancer therapy, could play a critical role in cancer treatment. In this review, we outline the key features and the molecular pathways of cellular senescence. Better understanding of cellular senescence will provide insights into the development of powerful strategies to control cellular senescence for therapeutic benefit. Lastly, we discuss existing strategies for the induction of cancer cell senescence to improve efficacy of anticancer therapy.

• Journal of Embryo Transfer
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• v.33 no.4
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• pp.237-243
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• 2018

Hedgehog (Hh) pathway plays a key role in development from invertebrate to vertebrate. It is known to be involved in cell differentiation, polarity, proliferation, including the development of vertebrate limb and the establishment of flies' body plan. To investigate how the regulation of Hh pathway affects the development of parthenogenetic murine embryos, the parthenogenetically activated murine embryos were treated with either cyclopamine (Cyc), an antagonist of Hh pathway, or purmorphamine, an agonist of Hh pathway. While Cyc did not affect the blastocyst formation and its total cell number, the chemical reduced the hatching rate of embryos and the expression levels of Fn1 mRNA. The results of the present study show the possibility that Cyc may affect the development of embryos at blastocyst stage by blocking Hh pathway and this may cause detrimental effect to the embryos at peri-, and post-implantation stages.

• BMB Reports
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• v.51 no.10
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• pp.493-499
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• 2018

Cellular senescence is a state of permanent cell-cycle arrest triggered by different internal and external stimuli. This phenomenon is considered to be both beneficial and detrimental depending on the cell types and biological contexts. During normal embryonic development and after tissue injury, cellular senescence is critical for tissue remodeling. In addition, this process is useful for arresting growth of tumor cells, particularly during early onset of tumorigenesis. However, accumulation of senescent cells decreases tissue regenerative capabilities and induces inflammation, which is responsible for cancer and organismal aging. Therefore cellular senescence has to be tightly regulated, and dysregulation might lead to the aging and human diseases. Among many regulators of cellular senescence, in this review, I will focus on microRNAs, small non-coding RNAs playing critical roles in diverse biological events including cellular senescence.