• Archives of Pharmacal Research
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• v.28 no.12
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• pp.1392-1399
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• 2005

This study evaluated the effect of $\alpha$-tocopherol ($\alpha$-TC), ischemic preconditioning (IPC) or a combination on the extent of mitochondrial injury caused by hepatic ischemia/reperfusion (I/R). Rats were pretreated with $\alpha$-TC (20 mg/kg per day, i.p.) for 3 days before sustained ischemia. A rat liver was preconditioned with 10 min of ischemia and 10 min of reperfusion, and was then subjected to 90 min of ischemia followed by 5 h or 24 h of reperfusion. I/R increased the aminotransferase activity and mitochondrial lipid peroxidation, whereas it decreased the mitochondrial glutamate dehydrogenase activity. $\alpha$-TC and IPC individually attenuated these changes. $\alpha$-TC combined with IPC ($\alpha$-TC+IPC) did not further attenuate the changes. The mitochondrial glutathione content decreased after 5 h reperfusion. This decrease was attenuated by $\alpha$-TC, IPC, and $\alpha$-TC+IPC. The significant production of peroxides observed after 10 min reperfusion subsequent to sustained ischemia was attenuated by $\alpha$-TC, IPC, and $\alpha$-TC+IPC. The mitochondria isolated after I/R were rapidly swollen. However, this swelling rate was reduced by $\alpha$­TC, IPC, and $\alpha$-TC+IPC. These results suggest that either $\alpha$-TC or IPC reduces the level of mitochondrial damage associated with oxidative stress caused by hepatic I/R, but $\alpha$- TC combined with IPC offers no significant additional protection.

• Tribology and Lubricants
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• v.35 no.3
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• pp.151-157
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• 2019

Insulated oil degradation produces charged by-products, such as acids and hydro-peroxides, which tend to reduce the insulating properties of the oil. In this study, UV-vis spectroscopy measurement technology is developed and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate its ability to monitor the degradation of electrical insulating paper. The degradation characteristics of the insulating paper are appropriately represented through various types of measurement methods, such as the Tan (delta) method, $CO_2$ gas production measurement, the titration method, and IR spectroscopy. The results are demonstrated to be well comparable to a change in the fluorescence emission ratio (FER), which is defined as the shift in fluorescence intensity in the measured wavelength range, and also to the chromatic ratio, which is defined as a color shift to longer wavelength ranges. The results also show that, by using UV-vis spectroscopy, it is possible to detect the degradation of the insulating paper. This study suggests that UV-vis spectroscopy can be applied as an alternative to high-performance liquid chromatography, which is the internationally recognized measurement technology for cellulose paper degradation. The FER detector is also verified to be useful as an effective condition-monitoring device for power transformers.

• Restorative Dentistry and Endodontics
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• v.49 no.2
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• pp.14.1-14.13
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• 2024

This study aimed to answer the question through a systematic review: Can carbamide peroxide be as effective as hydrogen peroxide and cause less in-office bleaching sensitivity? A literature survey was performed in PubMed/MEDLINE, Embase, Scopus, ISI Web of Science, and gray literature. Primary clinical trials that compared the efficacy or the in-office bleaching sensitivity between carbamide and hydrogen peroxides were included. The risk of bias was evaluated using the RoB2. The certainty of the evidence was assessed using the GRADE approach. DPI training significantly improved the mean scores of the dental undergraduates from 7.53 in the pre-DPI-training test to 9.01 in the post-DPI-training test (p < 0.001). After 6 weeks, the mean scores decreased marginally to 8.87 in the retention test (p = 0.563). DPI training increased their confidence level from 5.68 pre-DPI training to 7.09 post-DPI training. The limited evidence suggests that the 37% carbamide peroxide may be similarly effective to the 35% hydrogen peroxide for bleaching teeth in-office and causes less bleaching sensitivity. However, more well-designed split-mouth clinical trials are necessary to strengthen the evidence.

• Food Science and Biotechnology
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• v.17 no.1
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• pp.203-207
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• 2008

The present study aimed at assessing the protective effect of water extract from fruit body of the Grifola frondosa (GFW) on carbon tetrachloride ($CCl_4$)-induced hepatotoxicity. Rats orally administered with GFW 0.5, 1.0, 2.0 g/kg for 14 days were treated with $CCl_4$ to induce hepatotoxicity. Pretreatment with GFW remarkably prevented the elevation of serum AST, ALT, ALP, LDH, $\gamma$-GTP, and liver lipid peroxides in $CCl_4$-treated rat and GFW administration in liver injured rats by $CCl_4$ showed significant (p<0.05) protection of liver as evidenced from normal serum enzymes and malondialdehyde (MDA) levels. In the ultrastructural changes, administration of $CCl_4$-induced damage of hepatocytes with vacuolation, a highly damaged endoplasmic reticulum, and degenerating nuclei. However, pre-administration with GFW preserved normal ultrastructure of hepatocytes. These results suggest that GFW had an effect to inhibit $CCl_4$-induced liver injury in rat, and that it could be used as an effective hepatoprotective agent against chemical-induced liver damage.

• Journal of Nutrition and Health
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• v.44 no.6
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• pp.465-473
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• 2011

Dietary fatty acids are under intense research to identify anti-atherogenic mechanisms, so we investigated green tea powder (GT) as a protector against atherogenesis originating from lipid peroxidation such as 4-hydroxynonemal (4-HNE) and malondialdehyde (MDA) in different dietary fatty acid-treated apo E KO mice. Growth rate and dietary efficiency were lower in apo E KO mice with or without LA compared to wild type. Plasma total cholesterol (TC) and triacylglycerol (TG) did not correspond to values in other tissues, but TG in heart tissue decreased significantly by GT after linoleic acid (LA) or docosahexaenoic acid (DHA) was administered. LA induced apoptosis as evidenced by changes in aorta morphology and immunohistochemistry. Lipid peroxides (LPO) was increased in apo E KO mice with or without LA corresponding to the accumulation of 4-HNE or MDA in the proximal aorta above the atria. GT consumption tended to reduce the primary causal mechanism of atherogenic phenomena such as oxidizability in both LA and DHA treated atherogenic mice. A high polyunsaturated fatty acids (PUFA) diet involved the changes on stress-induced apoptotic signaling by increasing caspase 3, cytochrome c, and nuclear factor-${\kappa}B$ in the heart tissue, but decreasing the bcl-2 protein. However, GT remarkably reduced the expression of apoptotic signaling, in contrast to the PUFA diet. Therefore, the potential of GT as an anti-atherosclerotic dietary antioxidant was tested in this study.

• Nutritional Sciences
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• v.6 no.4
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• pp.195-200
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• 2003

In recent years, the prevalence of type 2 diabetes mellitus has dramatically increased in Korea as the diet has rapidly become westernized. We determined the effect of long-term cola intakes on glucose metabolism and oxidative stress in weanling male Sprague Dawley rats consuming a moderate fat diet Thirty male rats, born from 6 female rats, were randomized into cola or water drinking groups. For 28 weeks, all rats were provided with an ad lib solid diet having 33 percent of its metabolisable energy as fat In addition, rats of the cola group were provided with ad lib cola instead of water. The daily total caloric intake did not differ between groups. The rats in the cola group consumed a higher proportion of carbohydrates, and their mean body weight and fasting serum insulin level were lower than that of the control group. Whole-body glucose disposal rates measured by an euglycemic hyperinsulinemic clamp were higher in the cola group. However, lipid peroxide levels in kidney tissue were higher in the cola group than in the control group. Superoxide dismutase activity in kidney tissues was lower in the cola group compared to the control group, while glutathion peroxidase and catalase activities were not significantly different between the two groups. In conclusion, long-term cola intakes decreased insulin resistance, but increased oxidative stress in kidney tissue due to decreased SOD activities, which may lead to kidney damage. Thus, moderate changes in insulin resistance may not affect the status of oxidative stress, and vice versa.

• Toxicological Research
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• v.29 no.3
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• pp.187-193
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• 2013

The effects of toluene in dimethylformamide (DMF)-induced hepatotoxicity were investigated with respect to the induction of cytochrome P-450 (CYP) and the activities of related enzymes. The rats were treated intraperitoneally with the organic solvents in olive oil (Single treatment groups: 450 [D1], 900 [D2], 1,800 [D3] mg DMF, and 346 mg toluene [T] per kg of body weight; Combined treatment groups: D1+T, D2+T, and D3+T) once a day for three days, while the control group received just the olive oil. Each group consisted of 4 rats. The activities of the xenobiotic metabolic enzymes and the hepatic morphology were assessed. The immunoblots indicated that the expression of CYP2E1 was considerably enhanced depending on the dosage of DMF and the CYP2E1 blot densities were significantly increased after treatment with both DMF and toluene, compared to treatment with DMF alone. The activities of glutathione-S-transferase and glutathione peroxidase were either decreased or remained unaltered after treatment with DMF and toluene, whereas the lipid peroxide levels were increased with increasing dosage of DMF and toluene. The liver tissue in the D3 group (1,800 mg/kg of DMF) showed signs of microvacuolation in the central vein region and a large necrotic zone around the central vein, in rats treated with both DMF (1,800 mg/kg) and toluene (D3T). These results suggest that the expression of CYP2E1 is induced by DMF and enhanced by toluene. These changes may have facilitated the accelerated formation of N-methylformamide (NMF) from toluene, and the generated NMF may directly induce liver damage.

• Journal of Life Science
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• v.9 no.4
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• pp.466-472
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• 1999

These studies were designed to investigate the effects of pine (Pinus densiflora Sieb et Zucc.) needle extract (PNE) on oxygen radicals and their scavenger enzymes in liver membranes of Sprague-Dawley (SD) rats as a study on investigation of anti-aging effect and determination of chemical structures of PNE through the animal experiments. Male SD rats were fed basic diets (control group) and experimental diets (0.5% and 1.0%-PNE group) for 6 weeks. There were no significant differences in hydroxyl radical (·OH) formations of liver mitochondria and microsomes in 0.5%-PNE group, while ·OH formations were significantly decreased (10% and 18%, respectively) in liver mitochondria and microsomes of 1.0%-PNE group compared with control group. Microsomal hydrogen peroxides and cytosolic superoxide radicals were remarkably decreased (20% and 20∼25%, respectively) in 0.5% and 1.0%-PNE groups compared with control group. Mn-SOD activities in mitochondria were significantly increased about 10% in 1.0%-PNE group, while Mn-SOD activities in mocrosomes were remarkably increased (16∼20%) in 0.5% and 1.0%-PNE groups compared with control group. There were no significant differences in Cu, Zn-SOD activities of liver cytosol in 0.5% and 1.0%-PNE groups, while glutathione peroxidase (GSHPx) and catalase (CAT) activities were significantly decreased (28∼30% and 15∼30%, respectively) in liver cytosols of 0.5% and 1.0%-PNE groups compared with control group. These results suggest that these PNE may play a effective role in a attenuating a oxygen radical formations and increasing a scavenger enzyme activities.

• Journal of Nutrition and Health
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• v.37 no.7
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• pp.525-532
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• 2004

This study was performed to investigate the age-related changes of the lipid metabolism and thrombogenic capacity in Sprague-Dawley (SD) rats at the ages of 4, 8, 12, 16, 20 and 24 months old. Total lipid, triglyceride (TG) and total cholesterol in plasma and liver, HDL-cholesterol concentration, and eicosanoid contents in plasma were measured. Lipid peroxides were determined by the levels of thiobarbituric acid reactive substance (TBARS) in LDL fraction. Body weight was increased continuous until 16 months and decreased after 20 months. Epididymal fat pad (EFP) weight was increased continuously until 20 months and decreased at 24 months. Total lipid and TG concentrations in plasma were increased until 20 months and then rapidly decreased at 24 months but plasma cholesterol was increased continuously with aging. HDL-cholesterol level was increased continuously until 12 months, but decreased at 16 months and maintained there after. The TBARS levels in LDL fraction were the highest level at 24 months. Liver total lipid, TG, and total cholesterol concentrations were shown a tendency to increase with aging, and especially TG concentration was increased rapidly from 12 months to 16 months. Plasma thromboxane B$_2$ (TXB$_2$) and 6-keto-prostaglandin F$_1$ (6-keto-PGF$_1$) contents did not change with aging, but the ratio of TXB$_2$/6-keto-PGF$_1$ was increased with aging, especially from 8 to 12 months. These results showed that lipid levels in plasma and liver, TBARS levels in LDL fraction, and TXB$_2$/6-keto-PGF$_1$ ratio were increased with aging.

• Advances in Traditional Medicine
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• v.8 no.2
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• pp.146-153
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• 2008

The present study is aimed at finding the influence of silymarin (a flavonoid) (25 mg/kg & 50 mg/kg) in streptozotocin (STZ)-induced diabetic rats. Type 2 diabetes was induced by single intraperitoneal injection of STZ (100 mg/kg) to 3 days old rat pups. Silymarin was administered for 15 days after the animals were confirmed diabetic (75 days after STZ injection). Blood glucose, glycosylated hemoglobin ($HbA_{1c}$), lipid peroxides (LPO) levels and reduced glutathione (GSH) contents in pancreas and liver were estimated following the established procedures. Biochemical observations were further substantiated with histological examination of pancreas. Blood glucose and $HbA_{1c}$ levels, which were elevated by STZ, were lowered to physiological levels by the administration of silymarin. The levels of LPO were significantly increased in STZ-induced diabetic rats. Silymarin reduced the LPO levels in both pancreas and liver. GSH contents which were reduced significantly in pancreas and liver of STZ-induced diabetic rats were brought back to near normal levels by silymarin treatment. Multifocal necrotic and degenerative changes of pancreas in STZ-diabetic rats were minimized to near normal morphology by administration of silymarin as evident by histopathological examination. Silymarin showed a dose dependent protective effect on STZ-induced $\beta$-cell damage. It could be attributed to the antioxidative and free radicals scavenging properties of the flavonoid. Thus, it may be considered as a natural antioxidant with potential therapeutic application in the treatment of type 2 diabetes.