• Korean Journal of Exercise Nutrition
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• v.15 no.4
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• pp.153-161
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• 2011

The maintenance of skeletal muscle mass is very important for the prevention of life style-related diseases and the improvement of quality of life. It is well-known that resistance exercise and nutrition (especially amino acids) are the most effective interventions for maintaining skeletal muscle mass. It has been reported that many molecules are involved in the regulation of protein synthesis in response to resistance exercise and nutrition. Understanding the molecular mechanisms regulating muscle protein synthesis is crucial for the development of appropriate interventions. The role of intracellular signaling pathways through the mammalian target of rapamycin (mTOR), a serine/threonine protein kinase in the regulation of muscle protein synthesis, has been extensively investigated for these years. Control of protein synthesis by mTOR is mediated through phosphorylation of downstream targets that modulate translation initiation and elongation step. In contrast, upstream mediators regulating mTOR and protein synthesis in response to resistance exercise and amino acid still needed to be determined. In this brief review, we discuss the current progress of intracellular mechanisms for exercise- and amino acid-induced activation of mTOR pathways and protein synthesis in skeletal muscle.

• Korean Journal of Environmental Agriculture
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• v.31 no.1
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• pp.30-36
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• 2012

BACKGROUND: The resistance of rice bakanae disease pathogens against the fungicide prochloraz has been reported. Understanding the resistance mechanisms is an important for better control of the pathogens. In the present study, we investigated the resistance mechanisms of Fusarium fujikuroi CF337 (CF337) against prochloraz. METHODS AND RESULTS: Morphological changes in the cell wall of CF337 grown in potato dextrose broth (PDB) with or without prochloraz was investigated by transmission electron microscopy. Growth inhibition of CF337 was examined in PDB containing prochloraz or an ABC transporter inhibitor or both of them. Cell wall thickness of CF337 grown in PDB with prochloraz was significantly increased from $80.73{\pm}1.99nm$ to $193.11{\pm}7.07nm$. Significant inhibition in the growth of CF337 was observed in the presence of both prochloraz and the inhibitor, but no growth inhibition was observed in the presence of the inhibitor or prochloraz. Sequence analysis of ATP-binding cassette transporter (ABC) gene of CF337 showed 70 to 80% similarities to the genes of the pathogens resistant to other fungicides. CONCLUSION: Efflux transporter system and changes in cell wall thickness were suggested as resistance mechanisms of CF337 against prochloraz.

• The Journal of Korean Obstetrics and Gynecology
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• v.37 no.2
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• pp.35-57
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• 2024

Objectives: This systematic review of animal studies was designed to examine the therapeutic mechanisms of herbal medicines of insulin resistance in Polycystic ovary syndrome and composition of them. Methods: Studies were searched from PubMed, CNKI and Medline up to February 2024. Data was extracted and organized as animal model characteristics, treatment period, experimental and control group settings, evaluation index of treatment, therapeutic mechanism of herbal medicine and Composition of prescription. Results: In the 15 studies finally selected, the herbal medicine used in the study was effective in regulating the insulin resistance index, sex hormones and blood lipid index and improving the histological morphology of the ovaries. The herbal medicine prescriptions used in each of the 15 papers were different, and Salviae Miltiorrhizae Radix (丹參), Wolfiporia cocos (茯苓) and Epimedii Herba (淫羊藿) were most frequently used herbs, 7 times. Conclusions: The results showed that herbal medicine is effective in treating insulin resistance in Polycystic ovary syndrome through several mechanisms. The herbs used in more than 4 papers had effects such as anti-inflammatory, anti-oxidant, estradiol hormone production control and glycolipid metabolism control. More diverse clinical studies on insulin resistance in Polycystic ovary syndrome are needed.

• Korean Journal of Bronchoesophagology
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• v.5 no.2
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• pp.113-118
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• 1999

Background & Objectives : Nasal resistance which is halfly responsible for airway resistance is known to be influenced by hypoxia, hypercapnia, exercise, pregnancy, alcohol, ammonia and smoking. Smoking is a common part of our sociocultural environment and we have many a times been introduced to its various adverse effects, which have usually been more focused on lung problems. The purpose of this study is to determine any relationship between smoking and nasal resistance and to evaluate it's effective sites. Materials and Methods : Acoustic rhinometry was performed in 25 smokers and 25 nonsmokers who had no nasal symptoms nor abnormal rhinoscopic findings, and used an acoustic rhinometry to measure the distance from nose-piece to the C-notch, cross sectional area at the C-notch, and volume of the nasal cavity from nose-piece to 7cm. The authors compared the data between the two groups. Results : The cross sectional area at the C-notch was significantly decreased(p<0.05) in smoking group. The distance to the C-notch and the volume of nasal cavity were decreased likely in smoking group but there were no significant difference(p>0.05). Conclusion : Smoking reduced the cross sectional area at the C-notch, so increased the nasal resistance. The underlying mechanisms seems to be decreased nasal mucosal reactivity and congestion of the nasal mucosa. The authors believe there should follow more studies on pathophysiologic mechanisms and the histopathologic changes which involve the effect of smoking on nasal structures.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.10
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• pp.4879-4881
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• 2012

Epidermal growth factor receptor (EGFR) overexpression is associated with resistance to chemotherapy and radiotherapy. The EGFR modulates DNA repair after radiation-induced damage through an association with the catalytic subunit of DNA protein kinase. DNA double-strand breaks (DSBs) are the most lethal type of DNA damage induced by ionizing radiation, and non-homologous end joining is the predominant pathway for repair of radiation-induced DSBs. Some cell signaling pathways that respond to normal growth factors are abnormally activated in human cancer. These pathways also invoke the cell survival mechanisms that lead to resistance to radiation. The molecular connection between the EGFR and its control over DNA repair capacity appears to be mediated by one or more signaling pathways downstream of this receptor. The purpose of this mini-review was not only to highlight the relation of the EGFR signal as a regulatory mechanism to DNA repair and radiation resistance, but also to provide clues to improving existing radiation resistance through novel therapies based on the above-mentioned mechanism.

• Steel and Composite Structures
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• v.7 no.5
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• pp.377-390
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• 2007

In the design of concrete filled composite columns, it is assumed that the load transfer between the steel tube and concrete core has to be achieved by the natural bond. However, it is important to investigate the mechanisms of shear transfer due to the possibility of steel-concrete interface separation. This paper deals with the contribution of headed stud bolt shear connectors and angles to improve the shear resistance of the steel-concrete interface using push-out tests. In order to determine the influence of the shear connectors, altogether three specimens of concrete filled composite column were tested: one without mechanical shear connectors, one with four stud bolt shear connectors and one with four angles. The experimental results showed the mechanisms of shear transfer and also the contribution of the angles and stud bolts to the shear resistance and the force transfer capacity.

• The Plant Pathology Journal
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• v.26 no.2
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• pp.149-153
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• 2010

Biological and structural mechanisms of the nematode disease development in chili pepper caused by the root-knot nematode, Meloidogyne incognita, were investigated. Out of 39 chili pepper cultivars/lines tested, six were found resistant, while 33 were susceptible to M. incognita, of which a susceptible cultivar Chilseongcho and three resistant cultivar/lines CM334, 02G132 and 03G53 with different resistance degrees were selected for microscopic studies on the disease development. Gall formation was greatly reduced in the resistant cultivars/lines. Nematode penetration occurred both in the susceptible and resistant chili pepper roots; however, the penetration rates were significantly lowered in the three resistant peppers compared to the susceptible pepper cv. Chilseongcho. In the susceptible pepper, giant cells were extensively formed with no discernible necrosis around the nematode feeding sites. In the highly resistant pepper cultivar CM334, no giant cell was formed, but extensive necrosis formation was observed around the penetrating nematodes. In the other two resistant pepper lines (02G132 and 03G53), both giant cells and prominent necroses were formed, and the necrotic responses appeared to inhibit the further development of giant cells or accelerate their early degeneration. Although the nematode penetration was retarded significantly in the resistant cultivar/lines, all of the above results suggest that the disease resistance of pepper may be related to post-infectional defense mechanisms (nematode growth and development) more than pre-infectional ones (penetration and establishment). Variations in structural modifications in the resistant cultivar/lines may reflect their genetic differences related to the nematode resistance.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5915-5916
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• 2012

Human epidermal growth factor receptor (HER) 2 overexpression, observed in 20-25 percent of invasive breast cancers, is well known to be associated with a more aggressive phenotype and poor prognosis, with resistance to certain chemotherapeutic agents. The majority of patients with metastatic breast cancer who initially respond to trastuzumab, demonstrate disease progression within 1 year of treatment initiation. Furthermore, lack of response in some patients and relapse during the course of therapy, continue to challenge researchers and clinicians. A better understanding of the fundamental mechanisms of trastuzumab action is required so that new therapies directed at HER2 can be developed. We present here findings for mechanisms, both of Trastuzumab action and clinical resistance or escape.

• Journal of Yeungnam Medical Science
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• v.30 no.1
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• pp.4-9
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• 2013

Leptin, a 16-kDa cytokine, is secreted by adipose tissue in response to the surplus of fat store. Thereby, the brain is informed about the body's energy status. In the hypothalamus, leptin triggers specific neuronal subpopulations (e.g., POMC and NPY neurons) and activates several intracellular signaling events, including the JAK/STAT, MAPK, PI3K, and mTOR pathway, which eventually translates into decreased food intake and increased energy expenditure. Leptin signal is inhibited by a feedback inhibitory pathway mediated by SOCS3. PTP1B involves another inhibitory pathway of leptin. Leptin potently promotes fat mass loss and body weight reduction in lean subjects. However, it is not widely used in the clinical field because of leptin resistance, which is a common feature of obesity characterized by hyperleptinemia and the failure of exogenous leptin administration to provide therapeutic benefit in rodents and humans. The potential mechanisms of leptin resistance include the following: 1) increases in circulating leptin-binding proteins, 2) reduced transport of leptin across the blood-brain barrier, 3) decreased leptin receptor-B (LRB), and/or 4) the provocation of processes that diminish cellular leptin signaling (inflammation, endoplasmic reticulum stress, feedback inhibition, etc.). Thus, interference of the cellular mechanisms that attenuate leptin signaling improves leptin action in cells and animal models, suggesting the potential utility of these processes as points of therapeutic intervention. Various experimental trials and compounds that improve leptin resistance are introduced in this paper.

• Journal of Applied Reliability
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• v.13 no.3
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• pp.207-216
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• 2013

This paper, we classified LED failure mechanisms that occur due to the delamination and analyzed each of the mechanism that gives the LED PKGs the effect. Usually, the LED is composed of several materials which are LED chips, gold wire, phosphor, epoxy resin, adhesive, reflector and lead frame. These different materials are usually delaminated in trouble conditions which are huge temperature difference, hot and humid or mechanical shocked. When the components are delaminated, a luminance will be lost and moisture be absorbed easily, a thermal resistance be increased attendantly. In this paper, we experimented to investigate failure mechanism of the thermal resistance and failure mechanism of the decrease of luminance that occur due to the delamination. A thermal shock test was performed to reproduce this phenomena by subjecting samples to a cold-hot cyclling process between $-30^{\circ}C$(15min) and $110^{\circ}C$(15min). The samples were inspected at 200, 600 and 1,000 cycles. We measured feature of LED using the spatial analyzer, optical microscope, thermal resistance, photometer, scanning electron microscope (SEM). As a result, the progression of the crack and the thermal resistance and decrease in luminance are proportional to number of thermal shock.