268 research outputs found

    Reactive oxygen species regulate urokinase plasminogen activator expression and cell invasion via mitogen-activated protein kinase pathways after treatment with hepatocyte growth factor in stomach cancer cells

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    Abstract Background Reactive oxygen species (ROS) are closely associated with the intracellular signal cascade, thus strongly implicating involvement in tumor progression. However, the mechanism by which ROS are generated and how ROS target downstream molecules to trigger tumor metastasis is unclear. In this study, we investigated the underlying signal pathways in ROS-induced urokinase plasminogen activator (uPA) expression in the human gastric cancer cells, NUGC-3 and MKN-28. Methods and Results Intracellular ROS, as determined using the fluorescent probe, 2'-7' dichlorofluorescein diacetate, decreased after treatment with hepatocyte growth factor (HGF). We confirmed that Rac-1 regulated ROS production after activation of the AKT pathway with HGF. Exogenously added H2O2 promoted the expression of HGF, but not in a dose-dependent manner and also showed negative expression of HGF after co-treatment with H2O2 and HGF. Treatment with NAC, an intracellular free radical scavenger, decreased the enhancement of uPA production and tumor invasion in both cells. We clarified the downstream pathways regulated by ROS after treatment with H2O2, which showed negative control between FRK and p38 kinase activities for uPA regulation. Conclusion HGF regulates Rac-1-induced ROS production through the Akt pathway and ROS regulates uPA production and invasion via MAP kinase, which provides novel insight into the mechanisms underlying the progression of gastric cancer.</p

    Spatiotemporal Characteristics of Drought Occurrences over Japan

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    The drought climate of Japan from 1902 to 2009 was analyzed using an effective drought index (EDI). Drought regions were identified by hierarchical cluster analysis using drought characteristics (duration, severity, and onset and end dates) obtained from 50 observation stations. The results indicated that droughts could be divided into four groups (G1–G4) that reflected the local climate. The four groups were related to precipitation as follows. The summer rainy season affected groups G2–G4, in which droughts occurred mainly during spring and summer and were relieved before and after the rainy season. The G1 group was not affected by the summer rainy season and droughts were spread evenly throughout the year; it even had cases of droughts relieved by winter snow. All groups included dry conditions over the 108-yr period, and the driest conditions occurred in the late twentieth century. The statistical analysis of drought data showed that a total of 23 country-wide droughts occurred and that the most extreme droughts occurred in 1939–41 and 1984–85, with an EDI of −1.55. In addition, four dry seasons (1939–45, 1997–98, 1994–97, and 2005–09) were found using regime shift analysis. Regional droughts occurred 54, 54, 49, and 59 times in groups G1–G4, respectively. On average, short-term droughts with a duration shorter than 6 months occurred 3.5 times per decade, whereas long-term droughts extending over 1 yr occurred 0.3 times per decade. The drought duration and intensity were used to calculate the statistical return period of country-wide droughts. The 1939–41 drought had the longest return period, at 104.7 yr. The 1987–88 and 1995–97 droughts had return periods of 65.9 and 65.5 yr, respectively

    Enhanced black state induced by spatial silver nanoparticles in an electrochromic device

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    The use of three-dimensional (3D) hierarchical indium tin oxide (ITO) branches of electrochromic devices (ECDs) is an effective approach for increasing the optical properties via localized surface plasmon resonance compared with two- dimensional nanostructured electrodes. ECDs with 3D branches were designed to operate in transparent, mirror and black states. Finite- difference time- domain simulation was used to find the electrical field distributions in three types of ECD: glass/ITO with Ag film, glass/ITO branches and glass/ITO branches with Ag nanoparticles. The ECDs had an optical transmittance of 73.76% in the transparent state, a reflectance of 79.77% in the mirror state and a reflectance of 8.78% in the black state. We achieved an ECD with high stability that can show similar to 10 000 switching cycles among the three states.113Ysciescopu

    Biochars as Potential Adsorbers of CH4, CO2 and H2S

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    Methane gas, as one of the major biogases, is a potential source of renewable energy for power production. Biochar can be readily used to purify biogas contaminants such as H2S and CO2. This study assessed the adsorption of CH4, H2S, and CO2 onto four different types of biochars. The adsorption dynamics of biochars were investigated in a fixed-bed column, by determining the breakthrough curves and adsorption capacities of biochars. The physicochemical properties of biochars were considered to justify the adsorption performance. The results showed that CH4 was not adsorbed well by the subjected biochars whereas CO2 and H2S were successfully captured. The H2S and CO2 breakthrough capacity were related to both the surface adsorption and chemical reaction. The adsorption capacity was in the following order: perilla > soybean stover > Korean oak > Japanese oak biochars. The simultaneous adsorption also leads to a competition of sorption sites. Biochars are a promising material for the biogas purification industry

    Neuroprotective Activity of Sibjeondaebo-tang on Aβ Peptide-Induced Damages

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    Background. Sibjeondaebo-tang (SJDBT) has been used to treat diverse disorders including neuropsychiatric disabilities in traditional Korean medicine. Objective. The present study aims to investigate the potential effects of SJDBT on neuroprotection against Aβ peptide-induced damage using in vitro culture and in vivo rat brain systems. Materials and Methods. PC12 cell viability was analyzed by MTT assay, and neurite arborizations and caspase 3 protein signals in cultured PC12 cells and in vivo cortical neurons were analyzed by immunofluorescence staining. Phospho-Erk1/2 protein was analyzed by immunofluorescence staining and western blot analysis. Results. In PC12 cells, atrophied cell body and reduced neurite extension by Aβ treatment were recovered by SJDBT treatment. Caspase 3 protein signals were increased in Aβ-treated PC12 cells, but SJDBT treatment decreased apoptotic cell death. Caspase 3 activation in cortical neurons, which was induced similarly by Aβ treatment, was reduced by SJDBT treatment. Furthermore, phospho-Erk1/2 protein levels, which had been decreased by Aβ treatment, were elevated in the cortical neurons by SJDBT treatment. Conclusion. These data show that SJDBT may play a role in protecting from damages induced by Aβ in neuronal tissue and further suggest that SJDBT can be explored as the potential therapeutic target for AD treatments in human

    Foraging Behavior and Diet of Northward Migrating Bar-Tailed Godwits (Limosa laponica) and Great Knots (Calidris tenuirostris) at a Key Stopover Site

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    After the completion of the Saemangeum reclamation, the Geum Estuary has emerged as a key feeding and rooting site (staging site) for shorebirds in South Korea. However, there has yet to be any study conducted on the behavior and diet of shorebirds in this region. In this study, we first compared behavior and diet of two representative shorebird species with different morphologies, Bar-tailed Godwits (Limosa laponica) and Great Knots (Calidris tenuirostris) that co-occur in the tidal flat of Yubu Island near the Geum Estuary. During the April to May of 2016, using a camera equipped with a telescope, we recorded 36 individuals during low tide. Behavior was significantly different between the two shorebird species (Chi-square test, P = 0.037), although feeding success rate was similar between the two species (ANOVA, P &gt; 0.05); the Bar-tailed Godwit showed more probings and less peckings than the Great Knot. In addition, Bar-tailed Godwits walked less (ANOVA, P &lt; 0.001) and were less alert (ANOVA, P &lt; 0.005) than Great Knots. On the other hand, diet composition was significantly different between them (Chi-square test, P = 0.010); Both species fed mainly upon Mollusca but the Great Knot fed on noticeably more Annelida (lugworms) than the Bar-tailed Godwit. Among Mollusca, both species consumed more gastropods than bivalves (ANOVA, P &lt; 0.001).Based on these results, it is thought that Bar-tailed Godwits may save energy through less pecking together with less walking and less being alert, since it fed on less food than Great Knots. These results on behavior and diet will be helpful for conservation of the two species in the Geum Estuary tidal flats, a key stopover site of many shorebirds in the East Asian-Australasian Flyway (EAAF)

    Management of Cerebrospinal Fluid Leakage by Pump-Regulated Volumetric Continuous Lumbar Drainage Following Anterior Cervical Decompression and Fusion for Ossification of the Posterior Longitudinal Ligament

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    Objective Cerebrospinal fluid (CSF) leakage is a major concern related to anterior cervical decompression and fusion for ossification of the posterior longitudinal ligament (OPLL). We propose a management algorithm for CSF leakage following anterior cervical decompression and fusion for OPLL involving the use of pump-regulated volumetric continuous lumbar drainage. Methods We retrospectively reviewed patients who underwent anterior cervical decompression and fusion for OPLL and were managed with the proposed algorithm between March 2018 and July 2022. The proposed management algorithm for CSF leakage by pump-regulated volumetric continuous lumbar drainage was as follows. On exposure of the arachnoid membrane with or without CSF leakage, a dural sealant patch was applied to manage the dural defect. In case of persistent CSF leakage despite application of the dural sealant patch, patients underwent pump-regulated volumetric continuous lumbar drainage. Results Fifty-one patients were included in the study. CSF leakage occurred in 14 patients. Of these 14 patients, 9 patients underwent lumbar drain insertion according to the proposed management algorithm. Successful resolution of CSF leakage was observed in 8 of the 9 patients who underwent lumbar drainage. All patients were encouraged to ambulate without concern of CSF overdrainage due to gravity, because it could be avoided with pump-regulated volumetric continuous CSF drainage. Therefore, complications associated with absolute bed rest or CSF overdrainage were not observed. Conclusion The proposed management algorithm with pump-regulated volumetric continuous lumbar drainage showed safety and efficacy for management of CSF leakage following anterior decompression and fusion for OPLL

    Relationship Between Earlobe Crease and Brachial-ankle Pulse Wave Velocity in Non-hypertensive, Non-diabetic Adults in Korea

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    OBJECTIVES: Several studies have found a significant association between the presence of earlobe crease (ELC) and cardiovascular disease (CVD). Brachial-ankle Pulse Wave Velocity (baPWV) is a non-invasive and useful measure of arterial stiffness predicting cardiovascular events and mortality. However, few studies have reported the relationship between ELC and baPWV as a new measure of arterial stiffness. the purpose of this study was to determine whether ELC is related to baPWV in non-diabetic, non-hypertensive, and apparently healthy Korean adults. METHODS: A cross-sectional study was conducted on 573 non-hypertensive, non-diabetic Korean adults aged 20-80 yr. Subjects were stratified into three groups according to gender and menopausal status. baPWV was measured by an automatic waveform analyser. the association between ELC and baPWV was assessed by multiple linear regression analysis after adjusting for conventional cardiovascular disease risk factors including age, gender, blood pressure, lipid profile, and smoking status etc. RESULTS: the overall frequency of ELC was 19.02% and the subjects with ELC showed significantly higher mean baPWV (p<0.0001). Multiple linear regression of subjects revealed that the presence of ELC was independently associated with baPWV (male, p<0.0001; premenopausal female p=0.0162; postmenopausal female p=0.0208). CONCLUSION: ELC had a significant correlation with baPWV, independently controlling for other classical cardiovascular risk factors in adults aged 20 yr or older. ELC is an important surrogate marker of increased arterial stiffness as measured by baPWV in Korean adults.ope

    Biochars as Potential Adsorbers of CH4, CO2 and H2S

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    Methane gas, as one of the major biogases, is a potential source of renewable energy for power production. Biochar can be readily used to purify biogas contaminants such as H2S and CO2. This study assessed the adsorption of CH4, H2S, and CO2 onto four different types of biochars. The adsorption dynamics of biochars were investigated in a fixed-bed column, by determining the breakthrough curves and adsorption capacities of biochars. The physicochemical properties of biochars were considered to justify the adsorption performance. The results showed that CH4 was not adsorbed well by the subjected biochars whereas CO2 and H2S were successfully captured. The H2S and CO2 breakthrough capacity were related to both the surface adsorption and chemical reaction. The adsorption capacity was in the following order: perilla > soybean stover > Korean oak > Japanese oak biochars. The simultaneous adsorption also leads to a competition of sorption sites. Biochars are a promising material for the biogas purification industry

    The Role of HDAC6 in TDP-43-Induced Neurotoxicity and UPS Impairment

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    Transactive response DNA-binding protein 43 (TDP-43)-induced neurotoxicity is currently well recognized as a contributor to the pathology of amyotrophic lateral sclerosis (ALS), and the deposition of TDP-43 has been linked to other neurodegenerative diseases, such as frontotemporal lobar degeneration (FTLD) and Alzheimer&apos;s disease (AD). Recent studies also suggest that TDP-43-induced neurotoxicity is associated with ubiquitin-proteasome system (UPS) impairment. Histone deacetylase 6 (HDAC6) is a well-known cytosolic deacetylase enzyme that suppresses the toxicity of UPS impairment. However, the role of HDAC6 in TDP-43-induced neurodegeneration is largely unknown. In this study, we found that HDAC6 overexpression decreased the levels of insoluble and cytosolic TDP-43 protein in TDP-43-overexpressing N2a cells. In addition, TDP-43 overexpression upregulated HDAC6 protein and mRNA levels, and knockdown of Hdac6 elevated the total protein level of TDP-43. We further found that HDAC6 modulates TDP-43-induced UPS impairment via the autophagy-lysosome pathway (ALP). We also showed that TDP-43 promoted a short lifespan in flies and that the accumulation of ubiquitin aggregates and climbing defects were significantly rescued by overexpression of HDAC6 in flies. Taken together, these findings suggest that HDAC6 overexpression can mitigate neuronal toxicity caused by TDP-43-induced UPS impairment, which may represent a novel therapeutic approach for ALS.1
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