• The Korean Journal of Physiology and Pharmacology
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• v.16 no.6
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• pp.423-429
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• 2012

Brain ischemia leads to overstimulation of N-methyl-D-aspartate (NMDA) receptors, referred as excitotoxicity, which mediates neuronal cell death. However, less attention has been paid to changes in synaptic activity and morphology that could have an important impact on cell function and survival following ischemic insult. In this study, we investigated the effects of reperfusion after oxygen/glucose deprivation (OGD) not only upon neuronal cell death, but also on ultrastructural and biochemical characteristics of postsynaptic density (PSD) protein, in the stratum lucidum of the CA3 area in organotypic hippocampal slice cultures. After OGD/reperfusion, neurons were found to be damaged; the organelles such as mitochondria, endoplasmic reticulum, dendrites, and synaptic terminals were swollen; and the PSD became thicker and irregular. Ethanolic phosphotungstic acid staining showed that the density of PSD was significantly decreased, and the thickness and length of the PSD were significantly increased in the OGD/reperfusion group compared to the control. The levels of PSD proteins, including PSD-95, NMDA receptor 1, NMDA receptor 2B, and calcium/calmodulin-dependent protein kinase II, were significantly decreased following OGD/reperfusion. These results suggest that OGD/reperfusion induces significant modifications to PSDs in the CA3 area of organotypic hippocampal slice cultures, both morphologically and biochemically, and this may contribute to neuronal cell death and synaptic dysfunction after OGD/reperfusion.

• Communications for Statistical Applications and Methods
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• v.22 no.3
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• pp.233-239
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• 2015

This study compares two generalized Lindley distributions and assesses consistency between theoretical and analytical results. Data (complete and censored) assumed to follow the Lindley distribution are generated and analyzed using two generalized Lindley distributions, and maximum likelihood estimates of parameters from the generalized distributions are obtained. Size and power of tests of hypotheses on the parameters are assessed drawing on asymptotic properties of the maximum likelihood estimates. Results suggest that whereas size of some of the tests of hypotheses based on the considered generalized distributions are essentially ${\alpha}$-level, some are possibly not; power of tests of hypotheses on the Lindley distribution parameter from the two distributions differs.

• BMB Reports
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• v.45 no.8
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• pp.464-469
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• 2012

Endothelial cells (ECs) apoptosis induced by oxidized low-density lipoprotein (ox-LDL) is thought to play a critical role in atherosclerosis. MicroRNAs (miRNAs) are a class of noncoding RNAs that posttranscriptionally regulate the expression of genes involved in diverse cell functions, including differentiation, growth, proliferation, and apoptosis. MiRNA let-7 family is known to be involved in the regulation of cell apoptosis. However, the function of let-7 in ox-LDL induced ECs apoptosis and atherosclerosis is still unknown. Here, we show that let-7c expression was markedly up-regulated in ox-LDL induced apoptotic human umbilical cord vein endothelial cells (HUVECs). Let-7c over-expression enhanced apoptosis in ECs whereas inhibition of let-7c could partly alleviate apoptotic cell death mediated by ox-LDL. Searching for how let-7c affected apoptosis, we discovered that antiapoptotic protein Bcl-xl was a direct target of let-7c in ECs. Our data suggest that let-7c contributes to endothelial apoptosis through suppression of Bcl-xl.

• The Korea Journal of Herbology
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• v.21 no.4
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• pp.189-195
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• 2006

Objectives : It has been reported previously that the roots of Scutellaria baicalensis (known as Huang-Gum in Korean, henceforth referred to as S. baicalensis) could prevent neuronal cell death after global cerebral ischemia. In Genuine Korean medicine, S. baicalensis is known to relieve fever in upper body, and it was thus thought to be able to alleviate deteriorations in brain function. Methods : The protective effects of S. baicalensis against post-stroke memory retardation using 4-vessel occlusion model were examined in the present study. Results : S. baicalensis was shown to significantly alleviate the deficits in learning and memory by increasing the fraction of time spent in the quadrant in which the platform was initially placed ($34.9\;{\pm}\;3.2%$, p < 0.05) compared to that of the ischemia group ($28.0\;{\pm}\;2.5%$). The cytoprotective effect of S. baicalensis on CA1 hippocampal neurons was evaluated by measuring the neuronal cell density. Neuronal cell density in S. baicalensis extracts-treated ischemia group ($138.0\;{\pm}\;13.6\;cells/mm^2$) was significantly increased compared to saline-treated ischemia group ($22.1 \;{\pm}\;9.3\;cells/mm^2$, p < 0.05). In the study of OX-42 immunohistochemistry, S. baicalensis could decrease the micrgial activation in hippocampus after brain ischemia. Conclusion : These results may provide experimental support for the use of S. baicalensis in treating post-stroke memory impairment.

• IMMUNE NETWORK
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• v.24 no.3
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• pp.15.1-15.18
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• 2024

Osteoarthritis (OA) involves cartilage degeneration, thereby causing inflammation and pain. Cardiovascular diseases, such as dyslipidemia, are risk factors for OA; however, the mechanism is unclear. We investigated the effect of dyslipidemia on the development of OA. Treatment of cartilage cells with low-density lipoprotein (LDL) enhanced abnormal autophagy but suppressed normal autophagy and reduced the activity of transcription factor EB (TFEB), which is important for the function of lysosomes. Treatment of LDL-exposed chondrocytes with rapamycin, which activates TFEB, restored normal autophagy. Also, LDL enhanced the inflammatory death of chondrocytes, an effect reversed by rapamycin. In an animal model of hyperlipidemia-associated OA, dyslipidemia accelerated the development of OA, an effect reversed by treatment with a statin, an anti-dyslipidemia drug, or rapamycin, which activates TFEB. Dyslipidemia reduced the autophagic flux and induced necroptosis in the cartilage tissue of patients with OA. The levels of triglycerides, LDL, and total cholesterol were increased in patients with OA compared to those without OA. The C-reactive protein level of patients with dyslipidemia was higher than that of those without dyslipidemia after total knee replacement arthroplasty. In conclusion, oxidized LDL, an important risk factor of dyslipidemia, inhibited the activity of TFEB and reduced the autophagic flux, thereby inducing necroptosis in chondrocytes.

• Journal of Korea Entertainment Industry Association
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• v.15 no.2
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• pp.149-157
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• 2021

One year has passed since the pandemic of COVID-19, which occurred in Wuhan, China, in November 2019 began. Worldwide, as of January 2021, more than 95 million people have been infected, and the death toll is higher than 2 million. In Korea, there are 74,262 infected and 1,328 dead, and government policies such as social distancing to prevent infection are being implemented. Accordingly, many inconveniences occurred in the physical activity environment, such as the closure of various sports facilities. It was necessary to consider physical activities to maintain healthy life while cooperating with the national policy while preventing infection. This study investigated the benefits of physical activity to reduce the risk of trichomoniasis and diabetes, improve bone mineral density, prolong healthy lifespan, maintain activity performance with aging, and improve psychological anxiety and depression. In addition, the physiological changes that may occur in the situation of stopping exercise due to social distancing to prevent COVID-19 infection were reviewed. In addition, moderate-intensity exercise that helps strengthen immune function by activating natural killer cells, neutrophils, and antibody responses was investigated. In addition, it reduces the level and function of blood B-cells, T-cells, and natural killer cells for several hours, decreases phagocytosis of neutrophils in the nasal cavity, increases inflammatory cytokines, decreases immune function, and increases infection. High-intensity exercise was considered. Therefore, in the age of COVID-19, long-term high-intensity exercise such as marathon, which causes impaired immune function, should be refrained from. And you should do moderate-intensity regular aerobic exercise such as fast walking to help prevent infection. It is also recommended to participate in resistance exercises to prevent loss of muscle mass.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.5
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• pp.699-706
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• 2020

Predictive models in food microbiology are used for predicting microbial growth or death rates using mathematical and statistical tools considering the intrinsic and extrinsic factors of food. This study developed predictive growth models for Bacillus cereus on dried laver Pyropia pseudolinearis stored at different temperatures (5, 10, 15, 20, and 25℃). Primary models developed for specific growth rate (SGR), lag time (LT), and maximum population density (MPD) indicated a good fit (R²≥0.98) with the Gompertz equation. The SGR values were 0.03, 0.08, and 0.12, and the LT values were 12.64, 4.01, and 2.17 h, at the storage temperatures of 15, 20, and 25℃, respectively. Secondary models for the same parameters were determined via nonlinear regression as follows: SGR=0.0228-0.0069*T₁+0.0005*T₁²; LT=113.0685-9.6256*T₁+0.2079*T₁²; MPD=1.6630+0.4284*T₁-0.0080*T₁² (where T₁ is the storage temperature). The appropriateness of the secondary models was validated using statistical indices, such as mean squared error (MSE<0.01), bias factor (0.99≤B_f≤1.07), and accuracy factor (1.01≤A_f≤1.14). External validation was performed at three random temperatures, and the results were consistent with each other. Thus, these models may be useful for predicting the growth of B. cereus on dried laver.

• Toxicological Research
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• v.35 no.2
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• pp.181-190
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• 2019

Lentinus squarrosulus (Mont.) is an edible wild mushroom with tough fruiting body that belongs to the family Polyporaceae. It is used in ethnomedicine for the treatment of ulcer, anaemia, cough and fever. Recent studies have demonstrated its anticancer, anti-diabetic and antioxidant properties. However, little or no information is available regarding the bioactive components and toxicological study of wild dried L. squarrosulus. Therefore, this study investigated the bioactive components of aqueous extract of boiled wild dried L. squarrosulus and its toxicological effects in rats. The extract of L. squarrosulus was subjected to GC-MS analysis. The acute toxicity test was performed by oral administration of a single dose of up to 5,000 mg/kg extract of L. squarrosulus. In subacute study, the rats were orally administered extract of L. squarrosulus at the doses of 500, 1,000 and 1,500 mg/kg body weight daily for 14 days. The haematological, lipid profile, liver and kidney function parameters were determined and the histopathology of the liver and kidney were examined. The GC-MS analysis revealed the presence of bioactive compounds; 1-tetradecene, fumaric acid, monochloride, 6-ethyloct-3-yl ester, 9-eicosene, phytol, octahydropyrrolo[1,2-a]pyrazine and 3-trifluoroacetoxypentadecane. In acute toxicity study, neither death nor toxicity sign was recorded. In the sub-acute toxicity study, significant differences (p < 0.05) were observed on creatinine, aspartate aminotransferase, alanine aminotransferase, total cholesterol, triglycerides and high-density lipoprotein cholesterol. Whilst no significant differences (p > 0.05) were observed on packed cell volume, heamoglobin, red blood cell, white blood cell and alkaline phosphatase, in all the tested doses. No histopathological alterations were recorded. Our findings revealed that aqueous extract of L. squarrosulus may have antimicrobial, antinocieptive and antioxidant properties based on the result of GC-MS analysis. Results of the toxicity test showed no deleterious effect at the tested doses, suggesting that L. squarrosulus is safe for consumption at the tested doses.

• Journal of Nutrition and Health
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• v.36 no.9
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• pp.908-917
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• 2003

It has been proposed that oxidative modification of LDL (oxLDL) plays a significant role in the pathogenicity of atherogenesis. We tested the hypothesis that chitin and chitosan may function as antioxidants with respect to 0.1 mg cholesterol/ml LDL incubated with 5 $\mu$ M Cu$^2$$^{+}$alone or in the P338Dl mouse macrophage system using L-ascorbic acid as a standard classical antioxidant. The degree of oxLDL formation was ascertained by the relative electrophoretic mobility (rEM) in the combination of thiobarbituric acid reactive substances (TBARS) levels, and the cytotoxicity of oxLDL was detected by macrophage viability. The oxLDL uptake and foam cell formation of macrophages were measured by Oil Red O staining. Incubation with Cu$^2$$^{+}$and macrophages increased rEM of LDL and stimulated TBARS formation. Culture of macrophages with LDL in the presence 5 $\mu$ M Cu$^2$$^{+}$induced macrophage death. In cell-free system 200 $\mu$g/ml water-soluble chitosan and chitosan-oligosaccharide blocked oxLDL formation. Water-soluble chitosan and chitosan-oligosaccharide blocked oxLDL formation near-completely relative to L-ascorbic acid, whereas water-soluble chitin and chitin-oligosaccharide had no measurable antioxidant effect. In macrophage system water-soluble chitosan and chitosan-oligosaccharide blocked oxidation of LDL with a significant increase in cell viability, and decreased TBARS in medium. As for the inhibitory effect on macrophage foam cell formation, chitosan and its oligosaccharide, but not watersoluble chitin, revealed the effectiveness. The endothelial expression of lectin-like oxLDL receptor-1 (LOX-1) was tested by Western blot analysis, and chitosan, chitosan-oligosaccharide and chitin-oligosaccharide blocked LOX-1 expression. These results indicate that water-soluble chitosan and its oligosaccharide showed the inhibitory effect on Cu$^2$$^{+}$-induced LDL oxidation of macrophages, and chitosan, chitosan-oligosaccharide and chitin-oligosaccharide had blocking effect on oxLDL receptor expression in the human umbilical vein endothelial system. Thus, water-soluble chitosan and its oligosaccharides possess anti-atherogenic potentials possibly through the inhibition of macrophage LDL oxidation or endothelial oxLDL receptor expression depending on chemical types.l types.

• Journal of electromagnetic engineering and science
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• v.15 no.3
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• pp.142-150
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• 2015

Several reports supported that continuous exposure to 60 Hz magnetic field (MF) induces testicular germ cell apoptosis in vivo. We recently evaluated duration- and dose-dependent effects of continuous exposure to a 60 Hz MF on the testes in mice. BALB/c male mice were exposed to a 60 Hz MF at $100{\mu}T$ for 24 hours a day for 2, 4, 6, or 8 weeks, and at 2, 20 or $200{\mu}T$ for 24 hours a day for 8 weeks. To induce the apoptosis of testicular germ cell in mice, the minimum dose is $20{\mu}T$ at continuous exposure to a 60 Hz MF for 8 weeks, and the minimum duration is 6 weeks at continuous exposure of $100{\mu}T$. Continuous exposure to a 60 Hz MF might affect duration- and dose-dependent biological processes including apoptotic cell death and spermatogenesis in the male reproductive system of mice. The safety guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) indicates that the permissible maximum magnetic flux density for general public exposure is $200{\mu}T$ at 60 Hz EMF (ICNIRP Guidelines, 2010). In the present study, we aimed to examine the expression of pro- and anti-apoptotic genes regulated by the continuous exposure to 60 Hz at $200{\mu}T$ in Sprague-Dawley rats for 20 weeks. The continuous exposure to 60 Hz at $200{\mu}T$ does not affect the body and testicular weight in rats. However, exposure to 60 Hz MF significantly affects testicular germ cell apoptosis and sperm count. Further, the apoptosis-related gene was scrutinized after exposure to 60 Hz at $200{\mu}T$ for 20 weeks. We found that the message level of endonuclease G (EndoG) was greatly increased following the exposure to 60 Hz at $200{\mu}T$ compared with sham control. These data suggested that 60 Hz magnetic field induced testicular germ cell apoptosis through mitochondrial protein Endo G.